View source for Inline skates

{{Short description|Boots with wheels arranged in a single line}}
{{good article}}

[[File:Roces Impala 2023 Lightspeed Fairy Floss inline skates w 70mm 84A wheels-IMG 6848-bg-FRD.png|thumb|right|upright=0.8|Recreational skates]]
[[File:Powerslide Tau Urban Skates-110mm wheels-IMG 5286-BG Removed-FRD.png|thumb|right|Urban skates]]

'''Inline skates''' are [[boot]]s with [[wheel]]s arranged in a single line from front to back, allowing one to move in an [[ice skate]]-like fashion. Inline skates are technically a type of [[roller skates|roller skate]], but most people associate the term roller skates with quad skates, another type of roller skate with a two-by-two wheel arrangement similar to a car. Quad skates were popularized in the late 19th and early 20th centuries. Inline skates became prominent in the late 1980s with the rise of [[Rollerblade|Rollerblade, Inc.]], and peaked in the late 1990s. The registered [[trademark]] ''[[Rollerblade]]'' has since become a [[generic trademark]]: "rollerblading" is now a verb for skating with inline skates, or "rollerblades."

In the 21st century, inline skates come in many varieties, suitable for different types of [[inline skating]] activities and sports such as recreational skating, [[road skating|urban skating]], [[inline hockey|roller hockey]], [[street hockey]], [[Inline speed skating|speed skating]], [[Freestyle slalom skating|slalom skating]], [[Aggressive inline skating|aggressive skating]], [[vert skating]], and [[Artistic roller skating|artistic inline skating]]. Inline [[Ice skate|skaters]] can be found at traditional [[roller rinks]], street hockey rinks, [[skateparks]], and on urban streets. In cities around the world, skaters organize urban group skates. Paris Friday Night Fever Skate (Randonnée du Vendredi Soir) is renowned for its large crowd size, as well as its iconic +10 mile urban routes.<ref>{{cite web
|url=https://news.bbc.co.uk/2/hi/uk_news/2095023.stm
|title=The night of a thousand wheels
|website=BBC News
|date=20 July 2002
|url-status=live
|archive-url=https://web.archive.org/web/20080624192700/http://news.bbc.co.uk/2/hi/uk_news/2095023.stm
|archive-date=2008-06-24
}}</ref><ref>{{cite web
|url=http://www.pari-roller.com/
|title=Pari Roller – La Friday Night Fever !
|url-status=live
|archive-url=https://web.archive.org/web/20080130161111/http://www.pari-roller.com/
|archive-date=30 January 2008
}}</ref> Wednesday Night Skate NYC is its equivalent in New York City, also run by volunteers, albeit smaller in size.<ref>{{cite web
|url=http://www.skatecity.com/nyc/clubs/group.html
|title=Clubs and Leagues: Group Skates
|website=New York City Inline Skating Guide
|url-status=live
|archive-url=https://web.archive.org/web/20221203051227/http://www.skatecity.com/nyc/clubs/group.html
|archive-date=2022-12-03
}}</ref><ref>{{cite web
|url=https://www.empireskate.org/skate/
|title=NYC Skating Info Links
|website=Empire Skate Club of New York
|url-status=live
|archive-url=https://web.archive.org/web/20220709191604/https://www.empireskate.org/skate/
|archive-date=2022-07-09
}}</ref>

==History==

{{Main|History of inline skates}}

The documented history of inline skates dates back to the early 18th century, when enterprising inventors sought to make boots roll on wheels to emulate the gliding of ice blades on dry land. Because these wheeled skates were modeled after ice blades, their wheels were arranged in a single line. Skates were simply assumed to have a single runner, whether it was a steel blade on an [[ice skate]] or a row of wheels on a wheeled skate.<ref>{{cite web
|url=https://youraudiotour.com/tours/national-museum-of-roller-skating-audio-tour-museum-proper/stops/9802
|title=The First Roller Skates
|website=National Museum of Roller Skating Audio Tour
|url-status=live
|archive-url=https://web.archive.org/web/20241125040615/https://youraudiotour.com/tours/national-museum-of-roller-skating-audio-tour-museum-proper/stops/9802
|archive-date=2024-11-25
}}</ref>

=== Wheeled skates ===

{{Main|History of inline skates#Wheeled skates}}

[[File:Petibled-1819 wheeled skate-at National Museum of Roller Skating-by Bruce McArthur-landscape.jpg|thumb|right|upright=1.2|First patented wheeled skate - 1819]]

The first [[patent]]ed wheeled skate was filed in France in 1819 by Charles-Louis Petibled.<ref name="le-roller-en-ligne-on-charles-petibled">{{cite web
|url=https://www.rollerenligne.com/dossier/charles-louis-petibled-le-premier-brevet-de-lhistoire-du-patin-a-roulettes/
|title=Charles-Louis Petibled : le premier brevet de l'histoire du patin à roulettes
|website=Le Roller en Ligne
|date=30 March 2019
|url-status=live
|archive-url=https://web.archive.org/web/20240129130122/https://www.rollerenligne.com/dossier/charles-louis-petibled-le-premier-brevet-de-lhistoire-du-patin-a-roulettes/
|archive-date=2024-01-29
}}</ref> From that point forward, more patents and documented designs continued to explore wheeled alternatives to ice skates.<ref name="museum-of-roller-skating-history-of-roller-skating-1997"/> Around 1860, wheeled skates began to gain popularity, and new patents appeared under names such as "roller-skates" and "parlor skates". As inventions increased, roller skates began to diverge from the original single-line layout.<ref name="ols-history-skating-1760-to-today"/> Inventors experimented with two rows of wheels as a learning platform for beginner skaters.<ref name="Engineer-skates-no02"/> These double-row skates offered greater stability, but they were difficult to turn.<ref name="Engineer-skates-no03"/>

=== Roller skates ===

{{Main|History of inline skates#Roller skates|History of inline skates#Using ball bearings|l2=Using ball bearings}}

[[File:Plimpton Roller Skate prototype-between 1863 and 1866-at National Museum of Roller Skating-by Bruce McArthur.jpg|thumb|right|Plimpton prototype 1863-1866]]

In 1863, [[James Leonard Plimpton|James Plimpton]] invented a roller skate with four wheels arranged in a two-by-two configuration, similar to a [[wagon]], and added a clever mechanism for turning.<ref>{{Cite patent
|country=US
|number=37305
|pubdate=1863-01-06
|title=Improvement in skates
|inventor1-last=Plimpton
|inventor1-first=James
}}</ref>  It was the first double-row skate that allowed beginners to [[steering|steer]] easily by simply leaning in the desired direction.<ref>{{cite web
|url=https://youraudiotour.com/tours/national-museum-of-roller-skating-audio-tour-museum-proper/stops/9806
|title=The Father of the Modern Roller Skating
|website=National Museum of Roller Skating Audio Tour
|url-status=live
|archive-url=https://web.archive.org/web/20241128071950/https://youraudiotour.com/tours/national-museum-of-roller-skating-audio-tour-museum-proper/stops/9806
|archive-date=2024-11-28
}}</ref> Plimpton's invention sparked a rapid rise in roller skate popularity and spread across both sides of the [[Atlantic Ocean|Atlantic]], creating a period of "rinkomania" during the 1860s and 1870s.<ref>{{cite web
|url=https://www.bbc.com/news/magazine-31831110
|title=The Victorian craze that sparked a mini-sexual revolution
|website=BBC News
|date=6 April 2015
|url-status=live
|archive-url=https://web.archive.org/web/20241128071725/https://www.bbc.com/news/magazine-31831110
|archive-date=2024-11-28
}}</ref> His design also redefined the term "[[Roller skates|roller skate]]", which no longer referred to all wheeled skates but became synonymous with the "two-by-two" Plimpton style.{{efn-ua|name=vandervell-witham-1880-figure-skating-book-on-roller-skating|
Vandervell and Witham's 1880 book on figure skating not only covered ice skating, but dedicated a full chapter 5, named "Roller-Skating", to Plimpton's roller skates and to equivalencies of outside edges and club figures between his roller skates and ice skates. By 1880, the term "roller skates" were synonymous with Plimpton skates.<ref name="system-of-figure-skating-1880"/>{{rp|70–99}}
}}

=== After Plimpton ===

{{Main|History of inline skates#After Plimpton}}

[[File:Peck n Snyders Racing Roller Skate Ad-Spaldings Official Ice Hockey Guide-1904-Skate only.png|thumb|right|Racing Roller Skates - 1904]]

The development of precision [[ball bearing]]s in the mid-19th century helped make [[bicycle]]s more efficient and practical.<ref name="nasa-ball-bearings-1981">{{cite web
|url=https://ntrs.nasa.gov/api/citations/19810009866/downloads/19810009866.pdf
|title=History of Ball Bearings
|first1=Duncan
|last1=Dowson
|first2=Bernard J.
|last2=Hamrock
|year=1981
|website=NTRS - NASA Technical Reports Server
|url-status=live
|archive-url=https://web.archive.org/web/20241130044009/https://ntrs.nasa.gov/api/citations/19810009866/downloads/19810009866.pdf
|archive-date=2024-11-30
}}</ref> By the 1880s, Plimpton-style roller skates similarly incorporated ball bearings into their wheel assemblies, making skates roll more efficiently.<ref>{{Cite patent
|country=US
|number=308990
|pubdate=1884-12-09
|gdate=1884-12-09
|fdate=1884-08-06
|title=Roller-Skate
|inventor1-first=Levant Marvin
|inventor1-last=Richardson
}}</ref> At the same time, manufacturers began operating [[Roller rink|skating rinks]] as promotional ventures from the 1880s through the 1910s. All of these further fueled the Plimpton skate craze.<ref name="museum-of-roller-skating-history-of-roller-skating-1997"/>{{rp|19–20, 25}}

Although Plimpton's roller skates took center stage, inventors and enterprises continued to introduce new roller skates with a single line of wheels between the 1870s and the 1910s.<ref name="museum-of-roller-skating-history-of-inline"/> These models included features such as [[brake]]s, [[tire|pneumatic tires]], and [[History of inline skates#foot stand|foot stands]] placed below the center of the wheels.{{efn-ua|The main body of the skate is called the stock or foot stand, and is meant to be attached to the bottom of a shoe. See skates by Sherrif/Anderson and by Lindsley in the expanded [[History of inline skates#After Plimpton|After Plimpton section]] at the child article on [[History of inline skates|History]].
}}

=== Precursors ===

{{Main|History of inline skates#Precursors}}

[[File:Chicago Roller Blade-inline skate from ca 1965-patented by Gordon Ware-pic by Ojibwa-P1360137.jpg|thumb|right|upright=0.9|Chicago Roller-Blade - 1965]]

From the 1910s through the 1970s, many new variations of single-line wheeled skates were patented and manufactured.<ref>{{cite web
|url=https://www.inlineplanet.com/History/siffertjetskate.html
|title=The Illustrated History of Inline Skate Design At the U.S. Patent Office: Siffert's Jet Skate, 1938
|website=The Inline Planet
|author-first=Robert
|author-last=Burnson
|url-status=live
|archive-url=https://web.archive.org/web/20211207211716/https://www.inlineplanet.com/History/siffertjetskate.html
|archive-date=2021-12-07
}}</ref> While still in the shadow of 2x2 roller skates, some models began to gain popularity among [[ice hockey]] players by the 1960s and 1970s, due to their better emulation of ice blades. In particular, off-season training skates used by [[Soviet Union|USSR]] [[Speed skating|speed skaters]] inspired Gordon Ware of the Chicago Roller Skate Company to develop and patent a wheeled skate,<ref name="Gordon-Ware-patent-US3287023A"/> which was sold through [[Montgomery Ward]] in 1965 under the name "Roller-Blade".<ref name="shevelson-golden-days-of-skating-skaters-mag-premier-issue-1990"/>{{efn-ua|name=chicago-roller-blade-ads|See ads for the Chicago Roller-Blade in the 1965 Fall & Winter Montgomery Ward catalog, [http://www.thecatalogblog.com/wp-content/uploads/2020/02/mw65-wheels1.jpg page 1082], archived [https://web.archive.org/web/20241222023137/http://www.thecatalogblog.com/wp-content/uploads/2020/02/mw65-wheels1.jpg here], and in the 1965 Spring & Summer Catalog, [https://christmas.musetechnical.com/ShowCatalogPage/1965-Montgomery-Ward-Spring-Summer-Catalog/0846 page 846], archived [https://web.archive.org/web/20241222024629/http://web.archive.org/screenshot/https://christmas.musetechnical.com/ShowCatalogPage/1965-Montgomery-Ward-Spring-Summer-Catalog/0846 here].
}} In 1973, [[Ralph Backstrom]] promoted the Super Sport Skate,<ref name="maury-silver-tandem-skate-1975"/> a joint venture with his friend Maury Silver, as an off-season training tool for hockey players.<ref name="ross-holland-rollerblade">{{cite book
|chapter-url=https://archive.org/details/100greatbusiness0000ross/page/151/mode/1up
|title=100 Great Businesses and the Minds Behind Them
|chapter=Rollerblade - Live your product
|pages=151–155
|location=Naperville, Illinois
|publisher=Sourcebooks, Inc.
|year=2006
|isbn=978-1402206313
|access-date=2024-12-20
|first1=Emily
|last1=Ross
|first2=Angus
|last2=Holland
}}</ref>{{efn-ua|name=silver-super-sport-skate-ads-pics|See [https://web.archive.org/web/20241218042955/https://i.ebayimg.com/images/g/~bkAAOSw~I5jfSNO/s-l1600.webp ad for Super Sport Skates] endorsed by Ralph Backstrom in "Faceoff" 73 / 74 season by World Hockey Association.<ref>{{cite magazine
| author      = <!--Staff writer(s); no by-line.-->
| title       = Ad for Super Sport Skates by Super Skate Inc. sponsored by Ralph Backstrom
| url         = https://i.ebayimg.com/images/g/~bkAAOSw~I5jfSNO/s-l1600.webp
| magazine    = Faceoff 73 / 74 season
| publisher   = World Hockey Association
| year        = 1973
| archive-url = https://web.archive.org/web/20241218042955/https://i.ebayimg.com/images/g/~bkAAOSw~I5jfSNO/s-l1600.webp
| access-date = 2024-12-21
| archive-date = 18 December 2024
}}</ref> Also see archived pictures [https://web.archive.org/web/20241222040944/https://i.ebayimg.com/images/g/N4MAAOSwUNJnH8o~/s-l1600.webp one], [https://web.archive.org/web/20241222041243/https://i.ebayimg.com/images/g/MFsAAOSwgvhnH8o~/s-l1600.webp two], [https://web.archive.org/web/20241222041321/https://i.ebayimg.com/images/g/-KcAAOSwHfhnH8o~/s-l1600.webp three] and [https://web.archive.org/web/20241222041359/https://i.ebayimg.com/images/g/isQAAOSwRk1nH8o~/s-l1600.webp four], from an antique listing.
}} Both of these skate models became direct precursors to modern inline skates.{{efn-ua|Reference child article [[History of inline skates#Modern inline skates]] for details}}

[[File:Scott Olson-Early Rollerblade Prototype-CCM Super Tacks with Super Street Skate-2010-02-11.jpg|thumb|right|upright=0.9|CCM Tacks boot riveted to Super Street Skate ca. 1980]]

In a related development, the [[ski boot]] manufacturer [[Lange (ski boots)|Lange]] introduced the first [[Injection moulding|molded]] plastic ski boots with internal liners in the 1960s.<ref>{{cite web
|url=https://lange-ski-boots.blogspot.com/1970/01/early-days-1957-to-1963.html
|title=The early years - 1957 to 1963
|website=Lange - The History of an All-American Brand
|url-status=live
|archive-url=https://web.archive.org/web/20231124151740/https://lange-ski-boots.blogspot.com/1970/01/early-days-1957-to-1963.html
|archive-date=2023-11-24
|access-date=2024-12-27
}}</ref> In the 1970s, Lange entered the ice hockey market with similar [[#Hard boots|plastic boots featuring hinged cuffs]] and achieved some success.<ref>{{cite web
|url=https://lange-ski-boots.blogspot.com/2009/02/from-racing-glory-to-flo-leakage-1970.html
|title=From racing glory to bleeding "Flo" - 1970 to 1973
|website=Lange - The History of an All-American Brand
|date=2009-02-01 <!-- manually entered based on URL of the page. This article was not written in 1970: ARPANET was just being built. -->
|url-status=live
|archive-url=https://web.archive.org/web/20231124151648/https://lange-ski-boots.blogspot.com/2009/02/from-racing-glory-to-flo-leakage-1970.html
|archive-date=2023-11-24
|access-date=2024-12-27
}}</ref> Meanwhile, [[skateboarding]] reached new heights during the 1970s, thanks to the introduction of [[polyurethane]] wheels and their superior performance.<ref>{{cite magazine
| author      = <!--Staff writer(s); no by-line.-->
| title       = The Roller Renaissance: Forgiving, quiet urethane wheels and new suspension tricks have put a great sport back on its feet
| url         = https://books.google.com/books?id=YM8DAAAAMBAJ&pg=PA94
| magazine    = Popular Mechanics
| volume      = 151
| number      = 6
| page        = 94
| location    = Chicago
| publisher   = Popular Mechanics Company
| date        = June 1979
| access-date = 2024-12-20
}}</ref> The confluence of molded plastic boots with hinged cuffs, polyurethane wheels, Super Sport Skates, and the earlier Chicago Roller-Blade laid the foundation for the emergence of Rollerblade in the 1980s and its widespread appeal among the general public.<ref name="fried-cassorla-inline-ultimate-guide-1995"/>{{rp|12–16}}<ref name="shevelson-golden-days-of-skating-skaters-mag-premier-issue-1990"/>

=== Modern inline skates ===

{{Main|History of inline skates#Modern inline skates|History of inline skates#Rollerblade as a noun|l2=Rollerblade as a noun}}

[[File:Inline Skate-Hard boot-Rollerblade-Lightning TRS-1988-IMG 5703-FRD.png|thumb|right|upright|Lightning TRS from Rollerblade - 1988]]

[[File:Powerslide Tau Urban Skates-110mm wheels-IMG 5286-BG Removed-FRD.png|thumb|right|upright=0.9|Urban inline skates - 2024]]

In 1979, Scott Olson, a hockey player from [[Minneapolis]], discovered the Super Sport Skate. He began selling them to local hockey players as a licensed [[Distribution (marketing)|distributor]] and soon started modifying them.<ref>{{cite AV media
|first1=Steve
|last1=Hahn
|title=Steve Hahn interviews Scott Olson ( Rollerblade Founder )
|url=https://www.youtube.com/watch?v=7iaGK-FrN2Y
|via=YouTube
|publisher=Steven Hahn
|language=en
|format=video
|date=2012-02-06
}} Refer to the video transcript for this long interview, a part of the "Hockey in the Park" Series.
</ref> Olson, his brother Brennan, his family, and his friends replaced the stock boots with customers' old hockey boots and swapped out the original wheels for polyurethane ones.<ref name="MIA-olson-inventive-impulse"/><ref name="international-companies-vol34-rollerblade"/> Through further tinkering, prototyping and road testing everywhere he could, Olson eventually arrived at a skate design with a plastic ski boot, an adjustable/expandable frame, polyurethane wheels and double ball bearings.<ref name="bernstein-minnesota-hockey-inline"/><ref name="star-tribune-biz-on-a-roll">{{cite news
|author=<!--not stated-->
|date=1985-11-17
|title=A Business That's On a Roll
|url=https://www.newspapers.com/article/star-tribune-scott-olson-3/95325833/
|work=Star Tribune (Minneapolis)
|location=Minneapolis
|access-date=2024-12-23
 |via=[[Newspapers.com]]}}</ref>{{efn-ua|name="MIA-exhibit-notes"|The MIA exhibit story from 2015 includes a picture showing Scott Olson holding two prototype skates: 1) Lange boot on Super Street Skate skate with cream-colored wheels (1979), and 2) CCM Tacks hockey skate boot on his own adjustable/expandable skate design with orange polyurethane wheels (1981).<ref name="MIA-olson-inventive-impulse"/> Said picture is archived [https://web.archive.org/web/20241223184745im_/https://images.artsmia.org/wp-content/uploads/2015/06/01043323/2012-06-03-23.51.52-1067x800.jpg here]. The same two prototype skates are also seen in the main article picture of this [https://www.rollerblade.com/usa/en/the-rollerblade-experience/fitness/rollerblade-creator-scott-olson-will-attend-the-bmw-berlin-marathon Rollerblade article from 2019], archived [https://web.archive.org/web/20241224030540/https://www.rollerblade.com/usa/en/the-rollerblade-experience/fitness/rollerblade-creator-scott-olson-will-attend-the-bmw-berlin-marathon here]. The article picture is archived [https://web.archive.org/web/20241224030758/https://www.rollerblade.com/storage/thumbs/Article/2686__resize__16973Unknown-3.webp here].
}}{{efn-ua|See pictures of early prototypes of Ultimate Street Skate with "Ole's Innovative Sports" stamped on their frames, from [https://history.vintagemnhockey.com/page/show/1136093-minnesota-in-line-hockey-and-history-of-in-line-skates this page] on Vintage Minnesota Hockey, such as [https://cdn1.sportngin.com/attachments/photo/aaf9-144318485/Ole_s_Antique_Rollerblades_large.jpg this picture], [https://cdn1.sportngin.com/attachments/photo/23c9-144318495/Ole_s_Antique_Rollerblades-2_large.jpg this picture] and [https://cdn1.sportngin.com/attachments/photo/db66-144318486/Ole_s_Antique_Rollerblades-1_large.jpg this picture], plus [https://cdn1.sportngin.com/attachments/photo/1380-144026953/The_Ultimate_Rollerblade_Minneapoli_Ole_s_Innovative_Sports_Ad_large.jpg this ad]. Archived [https://web.archive.org/web/20240715001103/https://history.vintagemnhockey.com/page/show/1136093-minnesota-in-line-hockey-and-history-of-in-line-skates here], with [https://web.archive.org/web/20230531051459im_/https://cdn1.sportngin.com/attachments/photo/aaf9-144318485/Ole_s_Antique_Rollerblades_large.jpg picture], [https://web.archive.org/web/20230531051510im_/https://cdn1.sportngin.com/attachments/photo/23c9-144318495/Ole_s_Antique_Rollerblades-2_large.jpg picture], [https://web.archive.org/web/20230531051512im_/https://cdn1.sportngin.com/attachments/photo/db66-144318486/Ole_s_Antique_Rollerblades-1_large.jpg picture] and [https://web.archive.org/web/20230531051531im_/https://cdn1.sportngin.com/attachments/photo/1380-144026953/The_Ultimate_Rollerblade_Minneapoli_Ole_s_Innovative_Sports_Ad_large.jpg picture].<ref name="VMH-history-with-pic-gallery"/>
}} This skate rolled faster, and remained more reliable on road surfaces. However, a patent search revealed that the Chicago Roller-Blade already covered many of these features. In 1981, Olson persuaded the Chicago Roller Skate Company to transfer the patent to him in exchange for a share of future profits.<ref>{{cite AV media
 | people = Paula Schroeder (host)
 | date = 1995-07-31
 | title = Voices of Minnesota: Interview with Scott Olson (Part 1 of 3)
 | type = audio
 | language = en
 | url = https://archive.mpr.org/stories/1995/07/31/voices-minnesota-scott-olson-part-1-3
 | access-date = 2024-12-25
 | transcript=Transcript 1/3 in PDF
 | transcript-url = https://codytranscripts.apmcdn.org/production/9896941368e0d360b5826476023d7373.pdf
 | location = Minnesota
 | publisher = Minnesota Public Radio
}}</ref>

Thus began the modern history of inline skates, with Olson's company eventually becoming known as [[Rollerblade|Rollerblade, Inc.]] by around 1988.<ref>{{cite AV media
 | people = Paula Schroeder (host)
 | date = 1995-07-31
 | title = Voices of Minnesota: Interview with Scott Olson (Part 2 of 3)
 | type = audio
 | language = en
 | url = https://archive.mpr.org/stories/1995/07/31/voices-minnesota-scott-olson-part-2-3
 | access-date = 2024-12-25
 | transcript=Transcript 2/3 in PDF
 | transcript-url = https://codytranscripts.apmcdn.org/production/e8d38a90a9e6a9040b7960a9b73ec172.pdf
 | location = Minnesota
 | publisher = Minnesota Public Radio
}}</ref> The registered [[trademark]] "Rollerblade" became so well known that it entered common usage as a [[generic trademark]].<ref name="rollerblades-dryland-training-1985"/><ref name="mit-inventor-of-the-week-on-scott-olson-brennan-olson"/> Around this time, the company began promoting the term "in-line skating" in an effort to prevent "rollerblading" from becoming a verb.<ref name="international-companies-vol34-rollerblade"/><ref name="oxford_dictionary_word_rollderblade_as_brand_and_verb"/> The campaign proved effective, as media outlets, newspapers, and competitors adopted "in-line skating" as the preferred term by 1990.<ref name=nyt-1990-craze-outsprint/> The phrase was soon shortened to "inline", the name by which these skates are known today.{{efn-ua|Reference child article [[History of inline skates#Rollerblade as a noun]] for details}}

Modern inline skates became practical for [[mass production]] and appealing as a [[Recreation|recreational activity]] once key technologies came together. These included polyurethane wheels, [[International Organization for Standardization|ISO]] 608 standard ball bearings, and molded plastic boots. These skates incorporate double ball bearings with [[History of inline skates#Precursors|dual-purpose axles]] from Chomin Harry (1925),<ref name="chomin-harry-patent-US1527840"/> [[History of inline skates#Precursors|single-piece frames]] from Christian Siffert (1938),<ref name="siffert-christian-patent-US2113862"/> [[History of inline skates#Precursors|adjustable wheel rockering]] from Gordon Ware (1966),<ref name="Gordon-Ware-patent-US3287023A"/> [[History of inline skates#Precursors|single-unit boot/hockey frame with larger wheels]] from Maury Silver (1975),<ref name="maury-silver-tandem-skate-1975"/> plus additional innovations.{{efn-ua|The [[History of inline skates#Precursor|Precursor]] section of the child article on [[History of inline skates|History]] includes further details on Harry's dual-purpose axles, Siffert's single-piece frames, Ware's adjustable wheel rockering, and Silver's single-unit hockey skates.}}
{{Clear}}

== Design and function ==

=== Components ===

[[File:Inline skate parts-Boot-Frame-Wheels-PS Tau urban boot-Nexus Rocker 235mm frame-PS Spinner 90mm wheels-Right skate-IMG 3786-IMG 5890-FRD.png|thumb|right|Boot, frame, wheels, bearings, axles and tool]]

All modern inline skates share a common basic blueprint. A skate comprises a [[#Boots|boot]], worn on the foot. To the bottom of the boot is attached a [[#Frames|frame]], the most rigid part of the skate. The frame holds a number of [[#Wheels|wheel]] in place with wheel [[axle]]s. In between a wheel and an axle are two [[#Bearings|bearings]]. Bearings allow a wheel to rotate freely around its axle. Finally, a rubber [[#Heel brakes and toe stops|brake]] typically attaches to the frame of the right boot, on [[#Recreational|recreational skates]].<ref name="fried-cassorla-inline-ultimate-guide-1995"/>{{rp|17–27}}<ref name="powell-svensson-inline-skating"/>{{rp|14–39}}<ref name="miller-get-rolling-2003"/>{{rp|41–51}}

For many skaters, the frame is never removed or replaced. But wheels are consumables, as they wear down with use, and require periodic mounting rotations and even replacements.<ref name="rollerblades-dryland-training-1985"/>{{rp|81–86}} Inline skates usually come with a skate tool for wheel, bearing and frame maintenance. The tool will have a [[Hex key|hex wrench]] or a [[Torx|Torx wrench]] for removing wheel axles from a frame, and wherever applicable, for removing bearings from a wheel, and for removing a frame from a boot.<ref name="vegter-everthing-about-skate-tools">{{cite AV media
|first1=Ivo
|last1=Vegter
|title=Everything About Skate Tools
|url=https://www.youtube.com/watch?v=genZ_KT-nHY
|via=YouTube
|publisher=This is Soul
|language=en
|format=video
|date=2022-03-13
}} See video transcript on all types of skate tools with hex, Torx and other wrench tips for removing wheel, axels, frames and bearings.
</ref><ref name="fried-cassorla-inline-ultimate-guide-1995"/>{{rp|39–45}}<ref name="powell-svensson-inline-skating"/>{{rp|39–51}}

=== Securing the foot ===

{{multiple image
 | direction = horizontal
 | total_width = 340
 | image1 = Powerslide One Zoom-inline skates-IMG 5814-single skate-FRD.png
 | image2 = Inline-Skate-Soft-boot-K2-Cadence-SL.png
 | caption1 = Hard boot
 | caption2 = Soft boot
}}
[[File:Inline Skate-Hybrid boot with carbon shell-Powerslide Tau on Endless 90 frame with 3x110mm wheels-IMG 4271-FRD.png|thumb|right|upright=0.8|Hybrid boot]]

In the 1980s and 1990s, all inline skates had [[#Hard boots|hard boots]], borrowed from ski boot designs. A removable liner in a hard boot provides a snug yet comfortable fit between a skater's foot and the hard shell. Around 1996, [[K2 Sports|K2]] introduced [[#Soft boots|soft boots]] with an exoskeleton. These provide the most comfortable fit, at the expense of reduced rigidity. In the 2010s, [[#Hybrid boots|hybrid (soft) boots]] with an endoskeleton were introduced to the high-end market. A hybrid boot has an integrated, non-removable liner. This is glued to a rigid endoskeleton shell integrated with the sole, providing direct power transfer from the foot to the wheels.<ref name="gutman-catching-air-2004"/>{{rp|142}}<ref name="vegter-names-in-inline-skating"/><ref name="powerslide-hard-soft-hybrid-boots"/>

All three types are able to secure a foot in them without slack, with proper closure systems. Soft boots are often [[Shoelaces|laced]], and hard shells are usually secured with [[Tie down hardware|buckles]]. [[Hook-and-loop fastener|Velcro]] [[strap]]s are also common in all types of boots. Well-designed boots provide proper [[#Heel support|heel support]] and [[#Ankle support|ankle support]] to a skater.<ref name="powell-svensson-inline-skating"/>{{rp|14–39}}<ref name="miller-get-rolling-2003"/>{{rp|47–52}}<ref name="gutman-catching-air-2004"/>{{rp|142}}

=== Trade-offs ===

Choosing the right skates involves weighing various trade-offs. The [[#Frame dimensions|length of a frame]] positively affects stability and negatively affects turning agility. Longer frames accommodate more wheels, and taller frames larger wheels; both positively affect top skating speed. Modern inline skates are equipped with [[#Polyurethane wheels|polyurethane wheels]]. Softer wheels provide a better grip on smooth indoor surfaces, while harder wheels wear down less on rough outdoor surfaces. Beginners skate with all wheels touching the ground, for enhanced stability, known as a [[#Flat setup|flat wheel setup]]. Advanced skaters may choose to configure wheels in a [[#Rockered setup|rockered setup]] for enhanced maneuverability. The weight of a skate is an important consideration for some disciplines. Lighter boots, frames, and wheels are preferred. However, weight reduction is only achieved with escalating costs and [[diminishing returns]].<ref name="powell-svensson-inline-skating"/>{{rp|14–39}}<ref name="joyner-inline-hockey-1995"/>{{rp|19–33}}

=== Striding and gliding ===

{{multiple image
 | width = 160
 | image1 = Inline Alpine 2015 0219cropped.JPG
 | caption1 = Striding
 | image2 = 2008-06-28 Muenchen inlineslalommeisterschaft 002.JPG
 | caption2 = Gliding
}}

Recreational inline skating involves a continuous interplay between striding and gliding. As one foot pushes laterally against the ground during the striding phase, it converts sideways force into forward momentum. Meanwhile, the opposite foot glides ahead, supporting the skater's weight. These phases overlap fluidly, with each skate alternating between pushing and gliding in a coordinated rhythm that sustains forward motion.<ref name="skaters-mag-premier-issue-1990-on-getting-started-on-inlines"/><ref name="miller-get-rolling-2003"/>{{rp|57–75}}<ref name="publow-speed-skating-1999"/>{{rp|9–17}}

These two movements place distinct and often conflicting demands on skate design. A powerful stride benefits from a large contact area between the wheels and the ground, maximizing [[Friction#Static friction|static friction]] for a more forceful push-off. In contrast, a smooth and sustained glide calls for minimal contact to minimize [[Rolling resistance|rolling friction]]. Much of inline skate design involves balancing these opposing requirements to achieve both [[propulsion]] and [[Energy conversion efficiency|efficiency]].<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/><ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/>

=== Edging and turning ===

[[File:Foco Roberta in azione durante una run di Skate Slalom.jpg|thumb|right|upright=0.8|Edging for fast turns]]

[[File:Round profile and edging angles-Labeda inline skate wheel-80mm 85A-IMG 6359-FRD.png|thumb|right|upright=0.8|Three edging angles]]

Modern inline skate design was heavily influenced by ice hockey. Early inline skates from the 1980s aimed to replicate the feel of hockey skate blades, often using a [[#Rockered setup|rockered wheel setup]] to allow easier turning and quick directional changes. While [[Freestyle slalom skating|slalom skaters]] relied on these rockered setups and hockey players made rapid turns using [[Crossover (figure skating)|crossover]] maneuvers, recreational skaters soon realized that even a [[#Flat setup|flat wheel setup]] could support effective turning, thanks to the grip provided by polyurethane wheels on pavement. As with [[ice skating]], inline skaters could shift their body weight and apply pressure to one side of the skate to gradually turn while gliding.<ref name="rollerblades-dryland-training-1985"/>{{rp|81–86}}<ref name="skaters-mag-premier-issue-1990-on-getting-started-on-inlines"/><ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/><ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/>

This technique is known as "edging", which involves tilting the skate to roll on one side of the wheels. Skaters use both sides of the wheels for different maneuvers. The inside edge refers to the side of the wheel facing the skater's body, while the outside edge faces away.{{efn-ua|name="outside-inside-edges-terms"}} Edging is essential not only for turning but also for powerful stride pushes, which require a strong edge angle. Deep edging, however, requires proper support from the boot, frame, and wheels to prevent the foot from wobbling within the boot and to keep the wheels from sliding out from under the skater.<ref name="powell-svensson-inline-skating"/>{{rp|19–20,37–38}}<ref name="joyner-inline-hockey-1995"/>{{rp|19–24}}<ref name="miller-get-rolling-2003"/>{{rp|47–52}}

=== Heel support ===

Heel support refers to the ability of a boot to keep a skater's [[heel]] comfortably seated and firmly locked down in the heel pocket of the boot, even during aggressive maneuvering.<ref name="powell-svensson-inline-skating"/>{{rp|15–18}}

[[File:Heel support in an inline skate-illustration-IMG 4591-FRD.png|thumb|right|upright=1.5|A contoured heel pocket and a proper closure system work together to lock in the heel]]

A "heel pocket" is formed by the shell, inner liner and [[Shoe#sole|sole]] of a [[boot]]. A properly designed boot has a heel pocket that hugs the heel, with an [[Anatomy|anatomical]] contour. A proper [[#Securing the foot|closure system]] causes the "facing" (where eyelet tabs are) to push the [[Foot#Structure|instep]] against the heel pocket, preventing the foot from shifting or lifting during maneuvers. As a result, the heel remains in contact with the footbed at all times.<ref name="powell-svensson-inline-skating"/>{{rp|15–18}}<ref name="cheaney-anatomy-of-shoe">{{cite web
|url=https://www.cheaney.co.uk/anatomy-of-a-shoe-i278
|title=The Anatomy of a shoe
|website=Joseph Cheaney & Sons
|url-status=live
|archive-url=https://web.archive.org/web/20250724023837/https://www.cheaney.co.uk/anatomy-of-a-shoe-i278
|archive-date=2025-07-24
|access-date=2025-07-24
}}</ref>

=== Heel lock ===

Proper heel lock serves as a stable foundation for the entire foot. It allows a skater to adopt an athletic stance for skating by [[dorsiflexion|flexing]] the [[Tibia|lower leg]] forward, without lifting the heel from the insole. A snug fit means reduced movement of the foot within the skate, and thus reduced opportunity for friction to cause [[blister]]s. At the same time, the whole skate becomes transfixed to the foot as an extension of it, allowing efficient strides with a faithful transfer of power from the foot to the ground.<ref name="feineman-wheel-excitement"/>{{rp|35–36,79–80}}<ref name="powell-svensson-inline-skating"/>{{rp|15–17}}

=== Ankle support ===

[[File:Ankle support in an inline skate-illustration-IMG 4591-FRD.png|thumb|right|upright=1.5|Rigid carbon-fiber quarter panels of this hockey boot prevents sideway wobbles of the foot while allowing the shin to flex forward]]

Ankle support refers to the ability of a boot to prevent sideways movement of a skater's [[ankle]] and lower leg, while allowing the [[shinbone|shin]] to flex forward into an athletic stance. In some skates, such as [[#Recreational|recreational]] and [[#Aggressive|aggressive]] skates, this is achieved via a hinged cuff. In other skates, such as [[#Hockey|hockey]] skates, this is enabled by rigid, and anatomically shaped [[Types of inline skates#Hockey|quarter panels]] that lock the [[ankle]] in place, from two sides, leaving the shin to freely pivot forward.<ref name="powell-svensson-inline-skating"/>{{rp|5,15–18}}<ref name="vegter-hybrid-hard-boot-soft-boot"/><ref name="gutman-catching-air-2004"/>{{rp|142}}<ref name="skaters-mag-premier-issue-1990-on-quad-vs-inline"/> One primary concern of ankle support involves accommodating the two bony [[malleolus]] protrusions on either side of the ankle, colloquially known as ankle bones.{{efn-ua|name=ankle-bones-referring-to-malleolus|
"Anklebone" technically refers to the [[talus bone]], but laypeople usually refer to [[Malleolus#Medial malleolus|medial malleolus]] and [[Malleolus#Lateral malleolus|lateral malleolus]], the two bony protrusions on either side of the ankle, as ankle bones.<ref name="publow-speed-skating-1999"/>{{rp|308–311}} Boot designs are preoccupied with anatomically closing the foot, including these two malleolus bones. See claim 1 of the 2012 Bauer Hockey patent.<ref name="us-patent-8329083-wern-shiamg-jou-bauer-injection-molded-outer-wall-2007-2010"/>
}}

Proper ankle support allows a novice skater to keep a skate upright as a straight extension of their entire leg, when observed from the front. Without rigid support on both sides of the ankle, the foot may wobble within the boot, causing the skate to tilt inward or outward. This typically creates [[pronation]] in beginners based on natural [[Gait (human)|bipedal gait]], making it harder for a skater to glide on a single skate at best, and resulting in sprains and other injuries at worst.<ref name="xinhaidude-how-to-inline-skate"/>

=== Forward flex ===

[[File:Ankle support in an inline skate-Dorsiflexion in a hokey skate-IMG 1334-IMG 1333-FRD.png|thumb|right|upright|Dorsiflexion (left) vs leg extended straight (right)]]

A properly designed boot allows a skater to pivot the lower leg (the shin) forward about the [[Ankle|ankle joint]] to adopt a [[Squat (exercise)|squatting]] (athletic) stance, despite the sideway [[#Ankle support|ankle support]].<ref name="xinhaidude-how-to-inline-skate"/> This forward flex (or forward leaning) is known as [[dorsiflexion]] of the foot.<ref name="powell-svensson-inline-skating"/>{{rp|15–17}} It places the [[Center of mass|center of body mass]] atop the [[Ball (foot)|ball of the foot]], a balancing skill crucial to most skating moves.<ref name="feineman-wheel-excitement"/>{{rp|34–36}} This deep squatting posture also produces powerful [[#Striding and gliding|push-offs]], with the farthest displacement of the striding skate.<ref name="publow-speed-skating-1999"/>{{rp|5–11}}

Without such a squatting stance, the leg and the skate form a 90° angle, placing the entire body weight of a skater on the rear wheel of the skate. This is dangerous for a beginner because a small backward shift of the upper body will cause a skater to pivot their entire body on the rear wheel, and thus fall uncontrollably backward.<ref name="powell-svensson-inline-skating"/>{{rp|67–77}}<ref name="miller-get-rolling-2003"/>{{rp|57–59}}<ref name="skaters-mag-premier-issue-1990-on-getting-started-on-inlines"/>

=== Heel raise ===

Some inline skates feature a boot design where the [[heel]] is positioned substantially higher than the [[toe]]. This forward tilt encourages the skater to lean slightly forward by default, simulating a mild [[#Forward flex|forward flex]]. The design is commonly referred to as "heel raise" or a "raised heel".<ref name="endlessblading-geometry-of-inline-rocker-designs"/><ref name="back-to-blading-origin-of-UFS-and-mounting-standards"/> The height difference between the heel and toe is known in the [[footwear]] industry as the "heel-to-toe drop" or simply the "pitch".<ref name="runrepeat-heel-to-toe-drop"/><ref name="powerslide-download-guides-frames"/> Pitch can result from a combination of [[#Non-standard frames|frame mounting]] design, as seen in the [[#165mm and 195mm frames|165mm]] and [[#Trinity frames|Trinity]] standards,<ref name="bladeville-inline-skate-frames"/> and from using wheels of different sizes, as in [[#Hockey|hockey skates]] that employ a [[#Hi-lo setup|hi-lo setup]].<ref name="madison-rec-hockey-on-hi-lo-in-hockey-skates-vs-flat-setup"/>

Heel raise is sometimes called "heel lift".<ref name="vegter-review-seba-cj-skates">{{cite web
|url=https://www.thisissoul.com/blogs/reviews/review-seba-cj-skates
|title=Review Seba CJ skates
|date=2022-06-05
|website=This Is Soul
|url-status=live
|archive-url=https://web.archive.org/web/20250801003201/https://www.thisissoul.com/blogs/reviews/review-seba-cj-skates
|archive-date=2025-08-01
|access-date=2025-08-01
}} "heel raise" and "heel lift" used in the same text to refer to heel-to-toe drop.</ref><ref name="bladeville-product-powerslide-hardcore-evo-pro-90">{{cite web
|url=https://bladeville.com/powerslide-hardcore-evo-pro-90-black-red-boot-only.html
|title=Powerslide Hardcore EVO PRO 90
|website=Bladeville
|url-status=live
|archive-url=https://web.archive.org/web/20250801003635/https://bladeville.com/powerslide-hardcore-evo-pro-90-black-red-boot-only.html
|archive-date=2025-08-01
|access-date=2025-08-01
}} "heel raise" and "heel lift" used in the same text to refer to heel-to-toe drop.</ref> However, the term "heel lift" also colloquially describes a completely different condition: heel slippage - the lack of [[#Heel lock|heel lock]]. In this case, the heel lifts off the insole when the skater flexes the shin forward, which can lead to inefficiencies and blisters.<ref name="modsquadhockey-forums-73287-heel-slip-heel-lift">{{cite web
|url=https://modsquadhockey.com/forums/topic/73287-heel-slip-what-prevents-heel-slip-in-your-skates/
|title=Heel Slip: What prevents heel slip in your skates?
|date=2020-03-13
|website=Mod Squad Hockey
|url-status=live
|archive-url=https://web.archive.org/web/20250801004933/https://modsquadhockey.com/forums/topic/73287-heel-slip-what-prevents-heel-slip-in-your-skates/
|archive-date=2025-08-01
|access-date=2025-08-01
}} hockey players using the term "heel lift" to refer to heel slippage.</ref>
{{Clear}}

== Types ==
{{Main|Types of inline skates}}

[[File:Real inlinehockey pahalampi vs GBGCity.jpg|thumb|right|Inline hockey in Sweden]]

There are a variety of ways to design and make modern inline skates. Different types of inline skates reflect needs specific to different [[Inline Skating#Disciplines|inline skating disciplines]], such as recreational skating, [[road skating|urban skating]], [[inline hockey|roller hockey]], [[street hockey]], [[Inline speed skating|speed skating]], [[Freestyle slalom skating|slalom skating]], [[Aggressive inline skating|aggressive skating]], and [[Artistic roller skating|artistic inline skating]].

[[Manufacturing|Manufacturers]] and [[reseller]]s generally classify inline skates based on disciplines, such as aggressive skates, speed skates and hockey skates.<ref name="powell-svensson-inline-skating"/>{{rp|30–38}} Some disciplines are not large enough to warrant their own classification. Thus, dissimilar disciplines with similar equipment needs are grouped under a single skate category. For instance, freestyle skating, slalom skating, wizard skating, city commuting, and urban skating may be crammed into a single "urban skates" category.<ref name="inline-warehouse-choose-urban-skates"/> Then, there are the rest of skaters who casually skate, skate for [[Exercise|fitness]], or skate for [[cross-training]]. These purposes constitute 90% of actual inline skate [[sales]]. Skates suitable for these activities are often grouped together as "recreational skates".<ref name="vegter-names-in-inline-skating"/>

=== Recreational ===

{{multiple image
 | direction = vertical
 | width = 160
 | image1 = Roces Impala 2023 Lightspeed Fairy Floss inline skates w 70mm 84A wheels-IMG 6815-bg-FRD.png
 | caption1 = Recreational skates
 | image2 = Rollerblade Igniter S90 fitness inline skate.png
 | caption2 = Fitness skates
}}

{{Main|Types of inline skates#Recreational}}

Some makers refer to recreational skates as "fitness skates". Others split them into two or more categories: [[recreation]]al, [[Exercise|fitness]], and [[cross-training]]. Usually, the fitness and cross-training categories reflect increasing cost and thus quality of skates.{{efn-ua|1=See catalog pages from various makers and resellers in Jan 2025, for wildly different ways they classify recreational, fitness and cross-training skates: [https://www.rollerblade.com/usa/en/mens/recreational-skates Rollerblade] ([https://web.archive.org/web/20250106015156/https://www.rollerblade.com/usa/en/mens/recreational-skates archived]), [https://powerslide.com/pages/inline-skates-segments Powerslide] ([https://web.archive.org/web/20250106022709/https://powerslide.com/pages/inline-skates-segments archived]), [https://www.roces.com/en/skates/inline-skates.html?cat=180&product_list_order=price Roces] ([https://web.archive.org/web/20250106023008/https://www.roces.com/en/skates/inline-skates.html?cat=180&product_list_order=price archived]), [https://k2skates.com/en-us/c/inline-skates/?skate_category=Fitness,Lifestyle,Recreation,X-Training#clp-main K2] ([https://k2skates.com/en-us/c/inline-skates/?skate_category=Fitness,Lifestyle,Recreation,X-Training archived]), and [https://www.inlinewarehouse.com/How_to_Choose_Inline_Skates/catpage-BGIN.html Inline Warehouse] ([https://web.archive.org/web/20250106014828/https://www.inlinewarehouse.com/How_to_Choose_Inline_Skates/catpage-BGIN.html archived]). See Ivo Vegter's Youtube video on the classifications of recreational skates.<ref name="vegter-names-in-inline-skating"/>
}} [[#Soft boots|Soft boots]] with an exoskeleton are usually the least expensive. [[#Hard boots|Hard boots]] with removable liners are often priced higher. [[#Hybrid boots|Hybrid boots]] with an endoskeleton are high-end models.<ref name="vegter-hybrid-hard-boot-soft-boot"/><ref name="powerslide-hard-soft-hybrid-boots"/>

This category can be better understood as "unspecialized" inline skates, or generic skates. All other types of skates can be thought of as specialized deviations from this basic type.<ref name="vegter-names-in-inline-skating"/> Recreational skates usually come with four wheels of average size, and a frame of average length, which is just slightly longer than the boot. This places the front wheel halfway ahead of the toe box, and the rear wheel halfway behind the heel pocket, a design that remained unchanged since Scott Olson's adoption of [[History of inline skates#Precursors|Super Sport Skate]] from 1979.<ref name="maury-silver-tandem-skate-1975"/> Recreational skates are equipped with [[#Heel brakes and toe stops|heel brakes]]. These allow beginners to learn to stop rolling, with a simple pivot of a foot on its heel.<ref name="fried-cassorla-inline-ultimate-guide-1995"/>{{rp|25–26,44–45,52–57}}

=== Aggressive ===

{{Main|Types of inline skates#Aggressive}}

[[File:Aggressive Inline Skate-Gawds-Ground Control-Dead Wheels-Red-by IG Simply Vic-bg.png|thumb|right|upright=0.8|Aggressive skates]]

Aggressive skates are the most specialized inline skates, in contrast to recreational skates. They are designed for one specific purpose only: [[Aggressive inline skating|grinds]]. Grinding is the art of sliding on street obstacles such as [[stairs]], [[Handrail|rails]], [[Bench (furniture)|benches]], [[curb]]s, [[Inclined plane|ramps]] and [[wall]]s.<ref name="gutman-catching-air-2004"/>{{rp|134–163}}  To support these stunts, aggressive skates are generally built with strong [[#Hard boots|hard boots]] based on [[Ski boot#Alpine|plastic ski boots]] and bolted to thick [[#Frames|frames]] which are fitted with the smallest wheels in all of inline skating.<ref name="welch-demystify-inline-disciplines"/> To help a skater lock onto an obstacle of interest during a grind, an aggressive skate provides channels and surfaces such as H-blocks, frame grooves, backslide grooves, grind plates, [[soulplate]]s, etc.<ref name="bladeville-components-of-aggressive-skates"/> Transitioning between these stunts, a skater often jumps considerable heights, or rides down a long flight of stairs (known as stair bashing).<ref name="powell-svensson-inline-skating"/>{{rp|33,156–168}} Thus, aggressive boots are often fitted with shock absorbers to [[Damping|dampen]] shocks upon landing.<ref name="bladeville-components-of-aggressive-skates"/>

[[File:Inauguration du Skatepark de Plainpalais à Genève 03.JPG|thumb|right|upright=0.8|Park skating competition]]

[[History of inline skates#Modern inline skates|Rollerblade Lightning TRS]] has been widely credited for enabling [[aggressive inline skating]] as a sport, with its durable boot and its nylon-reinforced frame.<ref name="back-to-blading-origin-of-UFS-and-mounting-standards"/> Aggressive skates co-evolved with the discipline which started as "inline stunts".<ref name="feineman-wheel-excitement"/>{{rp|98–110}} It then turned into "streetstyle skating", and finally into "aggressive inline skating". The word "street" in "street-style" meant that skaters performed tricks on and over "street obstacles", following nomenclature from [[skateboarding]].<ref name="fried-cassorla-inline-ultimate-guide-1995"/>{{rp|6,64–77,170–174}} Skaters grind on street obstacles (termed "street skating"), perform stunts at [[skatepark]]s (termed "park skating"), and take to the air at the top of [[vert ramp]]s (termed "vert skating").<ref name="powell-svensson-inline-skating"/>{{rp|33,156–168}}

[[File:Aggressive Inline Skate-Gawds-Symetrics-Dead Wheels-Bottom view-by IG Simply Vic-bg rotated.png|thumb|right|upright=0.8|Frame groove and thick frame walls]]

Aggressive skates have [[Standardization|standardized]] on UFS, the Universal Frame System. Most UFS frames accommodate small wheels up to {{nowrap|60 mm}}.<ref name="vegter-everything-about-frames"/> Some UFS frames with frame grooves and H-blocks are designed with thick walls to prevent wheel bites. allowing them to be used with a [[#Flat setup|flat wheel setup]].<ref name="bladeville-components-of-aggressive-skates"/> Other UFS frames without prevention measures against wheel bites can be set up with an [[#Anti-rocker setup|anti-rocker wheel setup]], with even smaller and harder grindwheels (or antirockers) in the middle.<ref name="markus-thierstein-wheel-rockering"/> Some skaters go one step further, replacing the two middle wheels with non-rotating "juice blocks".<ref name="vegter-everything-about-grindwheels"/>

The name "aggressive" has been controversial.<ref>{{cite magazine
| author      = <!--Staff writer(s); no by-line.-->
| title       = What's in a name? Describing Skating to the Masses
| url         = https://be-mag.com/article/whats-in-a-name-describing-skating-to-the-masses/
| magazine    = Be-Mag
| date        = 2023-01-29
| archive-url = https://web.archive.org/web/20240915111023/https://be-mag.com/article/whats-in-a-name-describing-skating-to-the-masses/
| archive-date= 2024-09-15
| access-date = 2025-01-13
}}</ref> Many in the community call aggressive skating "rollerblading" (or simply "blading"), and thus members "bladers".<ref name="vegter-names-in-inline-skating"/> Others call it "aggro".<ref name="gutman-catching-air-2004"/>{{rp|134–163}}{{efn-ua|name=rollerblade-aggro-culture-1990|
Page 77 of Skaters magazine from 1990 featured an ad by Rollerblade on "Aggro Culture", an alternative term for aggressive inline skating. It urged readers to send $4 for an "Aggro Culture Poster". It's not clear whether Rollerblade promoted this term beyond 1990.<ref name="skaters-mag-premier-issue-1990-on-getting-started-on-inlines"/>}} Some skate manufacturers eschew the label "aggressive", choosing to market their aggressive skates instead as "street skates" or "park skates".<ref name="rollerblade-dk-superguides-inline-skating-2000"/>{{rp|40–41}}{{efn-ua|1=See archived product pages from Rollerblade: [https://web.archive.org/web/20110104214136/http://rollerblade.com/channel_street.php 2011 page] showing a selection of Rollerblade "Street Skates", [https://web.archive.org/web/20160315183029/http://www.rollerblade.com/usa/skates/?gen=28 2016 selection], and [https://web.archive.org/web/20241224030628/https://www.rollerblade.com/usa/en/mens/pro-skates/street-park 2024 selection].
}}

=== Hockey ===

{{Main|Types of inline skates#Hockey}}

[[File:Bauer Vapor Inline Hockey Skates-IMG 4412-FRD.png|thumb|right|upright|Bauer hockey skate]]

In the 21st century, the boots used for inline hockey skates (or roller hockey skates) are constructed using a process that differs significantly from those of other inline skates.<ref name="us-patent-7316083-labonte-traditiona-construction">{{Cite patent
|country=US
|number=7316083
|fdate=2004-03-29
|pubdate=2005-09-29
|gdate=2008-01-08
|title=Footwear having an outer shell of foam
|inventor1-first=Ivan
|inventor1-last=Labonté
|assign1=Bauer Hockey LLC
}}</ref> They are primarily produced by [[ice hockey]] manufacturers such as [[CCM (ice hockey)|CCM]], [[Bauer Hockey|Bauer]] ([[Mission Hockey|Mission]]), [[True Temper Sports|True]], and Marsblade.<ref name="powell-svensson-inline-skating"/>{{rp|37–38}}{{efn-ua|1=See inline hockey skates made by ice hockey manufacturers, archived here: [https://web.archive.org/web/20250117014217/https://www.inlinewarehouse.com/CCM_Super_Tacks_9370R/descpage-CST937S.html CCM Super Tacks 9370R], [https://web.archive.org/web/20250117014551/https://www.inlinewarehouse.com/Bauer_Vapor_3X_Pro/descpage-V3XPRS.html Bauer Vapor 3X Pro], [https://web.archive.org/web/20250117014732/https://www.inlinewarehouse.com/Mission_Inhaler_WM02/descpage-MWM2.html Mission Inhaler WM02], [https://archive.today/20250119220702/https://www.thehockeyshop.com/products/true-tf9-senior-roller-hockey-skates True TF9 Roller Hockey Skate], and [https://web.archive.org/web/20250117015104/https://www.inlinewarehouse.com/Marsblade_R1_Kraft_Crew/descpage-MKCR1.html Marsblade R1 Kraft Crew].|name=inline-hockey-skates-made-by-same-ice-hockey-makers}} In many cases, the same boot is used across both sports, with either a blade holder for ice hockey, or an inline frame for [[roller hockey]].{{efn-ua|name="note-on-complementary-hockey-making-video-patent"|1=Refer to [https://www.youtube.com/watch?v=vokXYoL1BsE this video] showing the production process of a Bauer hockey skate (both ice and inline), corresponding to the US patent 7,316,083. See FIG. 9: an exploded view showing components used in the construction of a traditional hockey skate in the 2010s.<ref name="youtube-discovery-uk-making-of-hockey-skates">{{cite web
|title=Ice Skates: How It's Made (Hockey Skates)
|url=https://www.youtube.com/watch?v=vokXYoL1BsE
|website=discoveryuk.com
|publisher=Discovery UK
|language=en
|format=video
|date=2020-06-05
}} Video shows the production process of a traditional hockey skate, with a boot that is fitted to either an ice blade or an inline wheel frame.</ref><ref name="us-patent-7316083-labonte-traditiona-construction"/>
}}{{efn-ua|1=See [https://patentimages.storage.googleapis.com/cb/bd/9c/cb7e75194591a7/US7039977.pdf US patent 7,039,977] filed by Mission Hockey in 2003, showing the same hockey boot construction, mounted on an ice blade (FIG. 1), and on a wheeled frame (FIG. 2).<ref name="us-patent-7039977-mission-bauer-2003"/>
}} As a result, inline hockey skates continue to rely on the [[Rivet|rivet-based]] mounting system used in ice hockey, even though replaceable frame standards have become common in other skate categories.<ref name="vegter-everything-about-frames"/>

[[File:Wern-Shiarng Jou-US8329083B2-2012-Method of making a lasted skate boot-Bauer-Patent Drawing Fig4-Redacted.png|thumb|right|upright|Hockey boot construction]]

Hockey skates feature some of the [[#Frame dimensions|shortest frames]] among all inline skates, enabling players to make tight turns and perform crossovers without interference. Hockey boots are designed to sit as low to the ground as possible, limiting them to smaller wheels. This configuration maximizes stability for [[#Edging and turning|hard edging]] maneuvers. Wheels with a [[#Wheel diameter and profile|rounder profile]] are preferred, as they offer improved [[Friction#Static friction|grip]] and control during sharp turns at all edging angles.<ref name="joyner-inline-hockey-1995"/>{{rp|19–24}}<ref name="powell-svensson-inline-skating"/>{{rp|37–38}} Many hockey skates use a [[#Hi-lo setup|hi-lo wheel setup]], with larger wheels in the rear and smaller ones in the front. This raises the heel and lowers the toe cap, thus the name "hi-lo". It causes a player to [[#Forward flex|forward flex]] naturally, for greater stability and stronger [[#Striding and gliding|strokes]].<ref name="rerolling-inline-boot-frame-wheel-setups"/>

The [[History of inline skates#Modern inline skates|modern inline skate]] was originally created as a training substitute for ice hockey skates, featuring a boot with a [[#Hard boots|hard shell]], pivoting cuff, and removable liner.<ref name="rollerblades-dryland-training-1985"/> This style of boot construction remains popular across all inline disciplines, ironically with the exception of inline hockey. Instead, hockey boots have followed their own path.<ref>{{cite web
|url=https://www.purehockey.com/c/the-history-of-hockey-skates-part-2
|title=The History of Hockey Skates, Part II: The Rise of Hockey-specific Skates
|website=Pure Hockey / Hockey Resource Center
|url-status=live
|archive-url=https://archive.today/20250117034047/https://www.purehockey.com/c/the-history-of-hockey-skates-part-2
|archive-date=2025-01-17
|access-date=2025-01-17
}} See discussion on how Lange hard boots did not fare well in ice hockey.
</ref>{{efn-ua|1=See background section discussion on why hard boots with hinged cuff and thick liners do not work to either ice hockey or roller hockey, in US patent 7,039,977 from Bauer/Mission.<ref name="us-patent-7039977-mission-bauer-2003">{{Cite patent
|country=US
|number=7039977
|fdate=2003-07-09
|pubdate=2004-05-06
|gdate=2006-05-09
|title=Contoured skate boot
|inventor1-first=Thomas V.
|inventor1-last=Wilder
|assign1=Mission Itech Hockey Inc
|assign2=Bauer Hockey LLC
}}</ref>
}} They are built to be as lightweight as economically feasible while still delivering excellent [[#Heel support|heel]] and [[#Ankle support|ankle support]], along with protection against impacts from flying pucks. Direct and immediate [[Energy conversion efficiency|power transfer]] from foot to wheel is also essential. To achieve this, hockey boots are constructed around an unyielding wall with [[Anatomy|anatomical]] contours to hug the heel and both sides of the ankle. This structure is called the "quarter package", made of left and right quarter panels bolted to a rigid [[Shoe#outsole|outsole]] platform.<ref name="us-patent-7039977-mission-bauer-2003"/><ref name="us-patent-7316083-labonte-traditiona-construction"/> The rest of the boot is built around this base, including a thick [[Shoe#upper|tongue]] that supports the shin in a forward-leaning athletic stance, and a reinforced [[Toe box|toe cap]]. The liner is integrated into the boot and not removable, with strategically varied thickness for best anatomical fit. Hockey skates are secured with eyelets and [[Shoelaces|laces]], rather than [[Tie down hardware|buckles]] or [[strap]]s.<ref name="us-patent-8329083-wern-shiamg-jou-bauer-injection-molded-outer-wall-2007-2010">{{Cite patent
|country=US
|number=8329083
|pridate=2007-01-19
|fdate=2010-07-12
|pubdate=2010-11-04
|gdate=2012-12-11
|title=Method of making a lasted skate boot
|inventor1-first=Wern-Shiarng
|inventor1-last=Jou
|assign1=Bauer Hockey LLC
}}</ref><ref name="youtube-discovery-uk-making-of-hockey-skates"/>

=== Speed ===

{{Main|Types of inline skates#Speed}}

[[File:P1030935k-speed-skate.png|thumb|right|upright=1.2|Speed skate with {{nowrap|100/90 mm}} wheels]]

Speed skates (or race skates) are purpose-built inline skates with a single goal: speed. They enable a [[Inline speed skating|racer]] to [[#Striding and gliding|stride]] with maximal efficiency and to [[#Striding and gliding|glide]] with the least amount of friction.<ref name="publow-speed-skating-1999"/>{{rp|3–9,283–318}} [[Joey Mantia]] holds the [[Inline speed skating#World records|world record]] for the outdoor 10-kilometers at over 27 miles per hour.<ref>{{cite web
|url=https://www.worldskate.org/speed/honor-roll.html
|title=World Speed Records - updated 2023
|website=World Skate
|url-status=live
|archive-url=https://web.archive.org/web/20250124040051/https://www.worldskate.org/speed/honor-roll.html
|archive-date=2025-01-24
|access-date=2025-01-24
}}</ref>

[[Inline speed skating|Speed skating]] differs from other inline disciplines in that a speed skater tilts her [[Torso|body trunk]] forward for up to 60° when racing, to reduce [[Drag (physics)|air resistance]]. A speed skater bends her knees aggressively for up to 80° in a deep-seated [[squatting position]] which requires a deep [[#Forward flex|forward leaning]] of the shin ([[dorsiflexion]]) for proper balance. This deep squatting posture produces the most powerful push-offs, with the farthest displacement of the pushing skate.<ref name="publow-speed-skating-1999"/>{{rp|5–11}}

[[File:INLINE SKATE.jpg|thumb|right|upright=1.2|Inline racing]]

Because of the need for a deep dorsiflexion, speed skates have no eyelets, buckles, or straps above middle eyelets at 45° angle. In order for racers to freely flex their foot around [[Malleolus|ankle bones]],{{efn-ua|name=ankle-bones-referring-to-malleolus}} speed boots are cut the lowest among all inline skates, around or below the ankle bones. The removal of shaft and cuff significantly reduces a boot's weight.<ref name="powell-svensson-inline-skating"/>{{rp|17,34–36}}<ref name="publow-speed-skating-1999"/>{{rp|3–30,308–311}} Most speed boots are custom-fitted without much padding, or else [[Shape-memory polymer|heat-moldable]], to prevent the foot from the slightest wobbling.<ref name="skatepro-all-aspects-of-speed-skates"/>{{efn-ua|1=Refer to this video showing the production process of a speed skate with a custom-molded carbon-fiber shell (both ice and inline).<ref name="youtube-discovery-plus-making-of-speed-skates">{{cite web
|title=How It's Made: Speed Skates
|url=https://www.youtube.com/watch?v=Mjs6eC3Wd-I
|website=discoveryplus.com
|publisher=Discovery Plus
|language=en
|format=video
|date=2022-04-14
}} Video shows the production process of custom-molded speed skates, with boots that could be fitted to either an ice blade or an inline wheel frame.</ref>
}}

The [[#Frames|frame]] may be made of aircraft-quality [[Aluminium|aluminum]], [[magnesium]], or possibly lightweight [[Carbon-fiber reinforced polymer|carbon fiber]], such that it flexes very little and transmits power from the foot to the wheels more directly. The length and height of a frame determine the number and size of wheels it can accommodate. More wheels and bigger wheels increase [[mass]], making [[acceleration]] harder and slower. But once rolling at speed, a skater can more easily maintain top speed given the [[moment of inertia|rotational inertia]]. In the 21st century, wheel size ranges from {{nowrap|90 mm}} to {{nowrap|125 mm}}. A [[#Wheel setup|setup]] with four {{nowrap|110 mm}} wheels (4x110mm) is typical for competitive speed skating, and three {{nowrap|125 mm}} wheels (3x125mm) for [[Inline speed skating|marathon skates]] at marathon events.<ref name="powell-svensson-inline-skating"/>{{rp|18–24,34–36}}<ref name="cadomotus-on-165mm-195mm-boots-on-ice-blades"/> Speed skates generally adopt either the [[#165mm and 195mm frames|165mm]] or the [[#165mm and 195mm frames|195mm]] mounting standard. Both of these 2-point mounting standards feature a built-in [[#Heel raise|heel raise]] that pitches a skater forward, creating forward flex.<ref name="bladeville-inline-skate-frames"/>

{{multiple image
 | direction = horizontal
 | image1 = Undercover Team Blank 110mm 86A inline skate wheel with Bones REDS bearings-IMG 4971-bg-FRD.png
 | image2 = Bullet profile-striding and gliding angles-Undercover inline skate wheel-110mm 86A-IMG 6784-FRD.png
 | total_width = 240
 | footer = Bullet profile: striding vs gliding
}}

Speed skating generally adopts [[#Wheel hardness and deformation|harder]] and [[#Wheel rebound|high-rebound]] wheels to minimize energy lost to [[Hysteresis|elastic hysteresis]]. Speed wheels have a pointy [[#Wheel diameter and profile|bullet profile]] that reduces friction from drags when gliding upright, while still providing a large contact surface for improved traction and control when pushing off at a [[#Edging and turning|deep edging angle]].<ref name="publow-speed-skating-1999"/>{{rp|315–316}} Speed skaters use High-quality [[#Bearings|bearings]] with precision ratings, and perform regular cleaning and lubrication to remove [[#Contamination and bearing friction|trapped dirt]] and restore them to their optimal performance.<ref name="fried-cassorla-inline-ultimate-guide-1995"/>{{rp|128–130}}

=== Urban ===

{{Main|Types of inline skates#Urban}}

[[File:Inline Skate-Hybrid boot with carbon shell-Powerslide Tau on Endless 90 frame with 3x110mm wheels-IMG 4271-FRD.png|thumb|right|Urban skate with 3 big wheels]]

Urban skate is an umbrella term for a type of skate suitable for several niche inline disciplines: freestyle skating, slalom skating, wizard skating, city commuting, and [[road skating|urban skating]]. These activities take place on relatively flat ground, but the surface may not always be paved or smooth.<ref name="inline-warehouse-choose-urban-skates"/>

'''Freestyle skating''' is named after its counterpart in [[skateboarding]], just like [[#Aggressive|aggressive]] street, park, and vert skating are named after street, park, and vert skateboarding, respectively. Freestyle skating is the art of performing skating tricks on relatively flat ground, free of obstacles.<ref name="vegter-naming-freestyle-aggro-street-skating"/> [[Freestyle slalom skating]] is a form of freestyle skating where tricks are performed around slalom cones. This is standardized by the International Freestyle Skaters Association (IFSA) and [[World Skate]] as "freestyle slalom" to distinguish it from "speed slalom", which is a form of speed skating around cones on flat ground.<ref name="ifsa-freestyle-slalom-rules">{{cite web
|url=http://ifsasports.org/English/Rules/freestyle.htm
|title=IFSA Freestyle Slalom Rules
|website=International Freestyle Skaters Association
|url-status=live
|archive-url=https://web.archive.org/web/20250205014428/http://ifsasports.org/English/Rules/freestyle.htm
|archive-date=2025-02-05
|access-date=2025-02-05
}}</ref><ref name="world-skate-freestyle-slalom-rules">{{cite web
|url=https://www.worldskate.org/inline-freestyle/about/regulations.html?download=4525:inline-freestyle-rulebook-2020
|title=World Skate Inline Freestyle Regulation
|website=World Skate
|url-status=live
|archive-url=https://web.archive.org/web/20240718231708/https://www.worldskate.org/inline-freestyle/about/regulations.html?download=4525:inline-freestyle-rulebook-2020
|archive-date=2024-07-18
|access-date=2025-02-05
}}</ref> Freestyle skating requires skates that support rigorous [[#Edging and turning|turning and edging]] maneuvers, with characteristics similar to [[#Hockey|hockey skates]]. A [[#Rockered setup|rockered setup]] with {{nowrap|76-80 mm}} wheels on a relatively [[#Frame dimensions|short frame]] is common for freestyle skating.<ref name="naomi-grigg-2014"/>{{rp|15–25}}<ref name="welch-demystify-inline-disciplines"/>

[[File:Patineur à Douala 17.jpg|thumb|right|Urban skating in Bonanjo]]

[[File:Powerslide Reign Ares hybrid skates-Trinity mount-215mm Ego SL frame-Heel to Toe Drop for Forward Lean-IMG 4820-bg-FRD.png|thumb|right|upright=0.8|Heel-to-toe drop on a Trinity frame]]

'''Urban skating''', also known as "city commuting", takes the activity to the [[street]]. But the term "street skating" is already taken as a subdiscipline of [[Aggressive inline skating|aggressive skating]], for grinding on street obstacles. Thus, this niche market is variously promoted as skating on [[Road surface|paved roads]] or [[commuting]] to work on skates. These activities demand [[#Frame dimensions|longer frames]] and [[#Wheel diameter and profile|larger wheels]] for higher cruising speed, stable tracking, and more comfortable rides on uneven surfaces, similar to [[#Speed|speed skates]] for marathon events. Common [[#Wheel setup|wheel setups]] include 4x80mm, 4x90mm, 4x100mm, 3x100mm, 3x110mm, and 3x125mm.<ref name="inline-warehouse-choose-urban-skates"/><ref name="welch-demystify-inline-disciplines"/> Most urban skate boots support either the [[#165mm and 195mm frames|165mm]] or [[#Trinity frames|Trinity]] mounting standard, and can be customized with a short frame and average-sized wheels for slalom skating, or with a long frame and large wheels for long-distance road skating.<ref name="vegter-everything-about-frames"/><ref name="inline-warehouse-frame-buying-guide"/> Both the 165mm and Trinity mounting standards raise the heel mounting platform higher than the toe, creating a slight "heel-to-toe drop", also known as a [[#Heel raise|heel raise]]. This drop causes the skater to lean forward by default, simulating a subtle [[#Forward flex|forward flex]] similar in purpose to the [[#Hi-lo setup|hi-lo wheel setup]] used in hockey skates.<ref name="vegter-everything-about-frames"/><ref name="xinhaidude-ps-trinity-reign-as-big-wheel-urban-skate"/>

'''Wizard skating''' is named after the company Wizard Skating, founded by Leon Basin in 2014. This form of skating is characterized by flowing footwork from freestyle, slalom, and [[figure skating]], while a skater blazes through roads, rolls over [[curb]]s, skates up [[Inclined plane|ramps]], bashes down [[stairs]], and [[parkour]]s on [[wall]]s. Leon perfected a type of "wizard" skate for this sport, featuring a long frame, large wheels, and a [[#Forward lean with a rocker|pre-rockered wheel setup]] for either 4 wheels or 5 wheels.<ref name="bladeville-wizard-frames-and-rest"/><ref name="welch-demystify-inline-disciplines"/> Skaters increasingly refer to this style as "flow skating".<ref name="vegter-names-in-inline-skating"/>
{{Clear}}

== Boots ==

=== Hard boots ===

{{multiple image
 | direction = vertical
 | width1 = 220
 | image1 = Inline skate parts-Hard Boot n Liner-Powerslide One Zoom-IMG 5938-IMG 5944-bg-FRD.png
 | width2 = 220
 | image2 = Inline skate parts-Hard Boot n Liner-Powerslide One Zoom-IMG 5949-IMG 5971-bg-FRD.png
 | caption2 = Hard boot with pivoting cuff, top buckle, 45° velcro strap, laced front facing, and removable liner
}}

Hard boots dominated the inline skate market in the 1980s and 1990s at the inception of [[#Modern inline skates|modern inline skating]], and [[History of inline skates#Modern inline skates|traced their design]] back to plastic ski boots from [[Lange (ski boots)|Lange]]. They have an outer shell made of [[plastic]], [[fiberglass]], [[Carbon-fiber reinforced polymer|carbon fiber]], or other solid materials. A removable liner in a hard boot provides a snug yet comfortable fit between a skater's foot and the hard shell.<ref name="vegter-hybrid-hard-boot-soft-boot"/><ref name="powerslide-hard-soft-hybrid-boots"/><ref name="skamidan-inline-skating-in-brief"/>

Hard boots commonly use a combination of [[Hook-and-loop fastener|velcro]] [[strap]]s and plastic [[Tie down hardware|buckles]] as closures. The cuff is usually secured with a top buckle. Some boots use [[Shoelaces|laces]] on the facing of the boot, while others have a front strap (or buckle) instead of or in addition to laces. The front lace and top buckle secure the foot inside the boot. To achieve proper [[#Heel lock|heel lock]], the liner is shaped to fit the heel, and a 45° strap (or buckle) presses the [[Foot#instep|instep]] of the foot against the contour of the liner.<ref name="powell-svensson-inline-skating"/>{{rp|15–18}}

[[File:Ankle support in an inline skate-Dorsiflexion in recreational hard boot skates-IMG 1342-IMG 1335-annotated.png|thumb|right|Hinged cuff: dorsiflexion (left) vs leg extended straight (right)]]

Hard boots have a high cuff (or shaft) to provide proper [[#Ankle support|ankle support]]. In order to accommodate [[#Forward flex|dorsiflexion]], the cuff is made to pivot near the [[Malleolus|ankle bones]]. As a skater leans their shin forward, the hinged cuff rotates to follow the lower leg while continuing to provide lateral ankle support.<ref name="powell-svensson-inline-skating"/>{{rp|15–18}}

Molds used in plastic [[Injection moulding|injection molding]] are expensive to make. As a result, plastic hard boots are usually available only in so-called "dual sizes". One hard shell is made for two US and EU [[shoe size]]s (e.g. US 9-10, and EU 42–43). A thicker liner is provided for US 9 and EU 42 to fill the gaps, while a thinner liner is provided for US 10 and EU 43. Some manufacturers offer "dual fit" liners, where the same liner can accommodate two shoe sizes using elastic parts, [[memory foam]], and other compressible space-filling materials.<ref name="vegter-hybrid-hard-boot-soft-boot"/><ref name="powell-svensson-inline-skating"/>{{rp|15–18}}

=== Soft boots ===

[[File:K2 Fatty SC-EU edition-aka US Backyard Bob-updated 1997 1998-Aggressive Inline Skates-A Schneider-IMG 0759-Profile-bg.png|thumb|right|upright|K2 Fatty SC, 1997]]

[[K2 Sports|K2]] introduced soft boots to inline skating in 1993 with its Exotech line of [[#Recreational|recreational skates]], marking the company's entry into the sport. Building on this innovation, K2 later released the legendary K2 Fatty, an [[#Aggressive|aggressive skate]] featuring the same soft-boot design. Since then, similar soft boots have come to dominate the recreational skate market.<ref>{{cite web
|url=https://www.historylink.org/File/3901
|title=K2 Corporation (K2 Sports) — a History
|first1=Andy
|last1=Luhn
|date=2002-07-23
|website=HistoryLink.org
|url-status=live
|archive-url=https://web.archive.org/web/20240914163503/https://www.historylink.org/File/3901
|archive-date=2024-09-14
|access-date=2025-02-18
}}</ref><ref name="gorski-skate-o-pedia-aggressive-skates"/>

They are akin to [[Hiking boot|hiking shoes]], made of [[textile]]s, [[mesh]], [[neoprene]], and other soft materials. Liners are integrated into the soft boot, and are thus not removable or replaceable. A soft boot is reinforced in strategic areas with a plastic [[exoskeleton]] for [[Structural analysis|structural support]].<ref name="powerslide-hard-soft-hybrid-boots"/><ref name="skamidan-inline-skating-in-brief"/><ref name="powell-svensson-inline-skating"/>{{rp|15–18}}

[[File:Child's Inline Skates-bg.png|thumb|right|upright|Rollerblade soft boots]]

[[File:Fila inline skates-bg.png|thumb|right|upright|Fila soft boots]]

A soft boot uses a pivoting cuff to support the lower leg, like [[#Hard boots|hard boots]]. Otherwise, its exoskeleton covers only a small area of the foot. This allows the boot to provide [[Passive ventilation|passive airflow]] through its fabric for moisture extraction, to keep the foot cool.<ref name="vegter-hybrid-hard-boot-soft-boot"/>

Soft boots use [[#Securing the foot|closure systems]]  similar to those of hard boots. These include [[Shoelaces|laces]], [[Hook-and-loop fastener|velcro]] [[strap]]s, and plastic [[Tie down hardware|buckles]]. Lacing the front of the boot is key to securing the foot within the boot, due to the lack of exoskeleton support in this area. On the other hand, the flexible front of the boot readily accommodates different shapes of foot. Soft boots thus provide a more comfortable fit at the expense of reduced rigidity and support, making them suitable for beginners and casual skaters. Committed enthusiasts, however, generally avoid soft boots due to their lack of direct and immediate response to skating moves, a result of [[elastic hysteresis]].<ref name="vegter-hybrid-hard-boot-soft-boot"/>

Soft boots are lighter and generally more affordable than hard boots. They are also easier to manufacture in precise [[shoe size]]s. While hard boots typically come in "dual sizes", soft boots are available in "half sizes" for US shoe measurements (e.g., US 9.5, 10, and 10.5) and, in some cases, for EU sizes as well (e.g., EU 39.5, 40, and 40.5).<ref name="vegter-hybrid-hard-boot-soft-boot"/><ref name="powell-svensson-inline-skating"/>{{rp|15–18}}

=== Hybrid boots ===

{{multiple image
 | direction = horizontal
 | image1 = Hybrid soft boot-Inline skate with a carbon fiber shell-PS Tau.png
 | image2 = Hybrid soft boot-Inline skate with a carbon fiber shell-PS Tau-shell highlighted.png
 | caption1 = Hybrid soft boot
 | caption2 = Endoskeleton shell 
 | width1 = 180
 | width2 = 180
}}

{{multiple image
 | direction = horizontal
 | image1 = Powerslide Tau urban skate vs its hybrid carbon fiber shell-original frame w 90mm wheels-IMG 3786-FRD.jpg
 | image2 = Hybrid soft boot-Inline skate with a carbon fiber shell-PS Tau-translucent showing a foot.png
 | caption1 = Carbon shell
 | caption2 = Foot and shell
 | width1 = 180
 | width2 = 150
}}

Hybrid boots, also known as hybrid soft boots, look superficially similar to [[#Soft boots|soft boots]], complete with soft materials covering a large part of the boot. Unlike soft boots, however, hybrid boots have no [[exoskeleton]] reinforcement apart from the pivoting cuff. These boots have an [[endoskeleton]] instead, in the form of a [[Composite material|composite]] shell. The shell serves as the sole of the boot, with shell walls extending upward from the sole. The soft upper part of the boot is pulled taut over the shell and glued onto it.<ref name="powerslide-hard-soft-hybrid-boots"/><ref name="vegter-hybrid-hard-boot-soft-boot"/>

Hybrid boots are lighter than [[#Hard boots|hard boots]] and soft boots. Yet they remain rigid where the foot meets the boot. Integrated liners in hybrid boots can be made thinner than removable liners in hard boots. In higher-end hybrid boots, the integrated liner is [[Shape-memory polymer|heat-moldable]] for the best custom fit, and the shell is made of [[Carbon-fiber reinforced polymer|carbon fiber]]. A hybrid shell sits much closer to the foot than a hard shell or the exoskeleton of a soft boot. As a result, hybrid boots provide more direct and responsive [[Energy conversion efficiency|power transfer]] from a foot to wheels.<ref name="powerslide-hard-soft-hybrid-boots"/><ref name="xinhaidude-carbon-fiber-inline-skates"/>

Hybrid boots originated from the development of carbon shells in [[#Speed|speed skates]] during the 1990s and 2000s. In the 2020s, manufacturers like Powerslide offer hybrid inline skates, including models such as the Hardcore Evo, Tau, and Swell. However, the term "hybrid" has yet to gain universal acceptance, and these boots are often marketed as high-end soft boots.<ref name="powerslide-hard-soft-hybrid-boots"/><ref name="bladeville-hybrid-softboots">{{cite web
|url=https://bladeville.com/blog/softboot-skates-not-that-bad-actually
|title=Softboots - not that bad, actually!
|website=Bladeville
|date=2022-04-02
|url-status=live
|archive-url=https://web.archive.org/web/20230525050100/https://bladeville.com/blog/softboot-skates-not-that-bad-actually
|archive-date=2023-05-25
|access-date=2025-02-01
}}</ref><ref>{{cite AV media
|first1=Ricardo
|last1=Lino
|title=Soft boot vs hard boot - skates vlog132
|url=https://www.youtube.com/watch?v=cHDP3pm46FY
|via=YouTube
|language=en
|format=video
|date=2017-08-02
}} See video transcript.</ref>

=== One-piece carbon boots ===

[[File:TRUE inline hockey skate vs its one-piece carbon fiber shell-TF Pro Senior Custom-IMG 4440-FRD.jpg|thumb|right|upright|Monocoque shell]]

{{multiple image
 | direction = horizontal
 | total_width = 240
 | footer = TF Pro inline skate vs. ice skate
 | image1 = TRUE Inline Hockey Skates-Riveted Frame and Wheels-low perspective view-IMG 4591-FRD.png
 | image2 = TRUE Ice Hockey Skates-Riveted Frame and Wheels-low perspective view-IMG 4603-FRD.png
}}

{{Main|Types of inline skates#One-piece carbon boot}}

In the 21st century, [[#Hockey|hockey skates]] increasingly favor "one-piece" carbon boots with a [[monocoque]] shell that were first developed in the 1990s for [[#Speed|speed skating]]. These boots are unlike the three common types of inline boots: [[#Hard boots|hard]], [[#Soft boots|soft]] and [[#Hybrid boots|hybrid]]. The one-piece boots are built around a [[Carbon-fiber reinforced polymer|carbon fiber-reinforced]] [[Composite material|composite]] shell, where the shell almost completely surrounds a foot. After eyelet holes are punched out of a shell, the shell is usable as a functional boot if laced.<ref name="vh-hockey-about-page-before-2015">{{cite web
|url=http://www.vhhockey.com/about
|title=About VH Hockey
|website=VH Hockey
|url-status=dead
|archive-url=https://web.archive.org/web/20150225151309/http://www.vhhockey.com/about
|archive-date=2015-02-25
|access-date=2025-01-18
}}</ref>

For instance, [[Easton Sports|Easton]]'s Synergy 1300C came out in 2005, with a unitary shell made with carbon and [[aramid]] fibers. This is widely recognized as the first retail hockey skate with a composite shell.<ref>{{cite web
|url=https://www.hockeyworld.com/Easton-Synergy-1300C-Hockey-Skates-05-Model-Senior
|title=Easton Synergy 1300C Hockey Skates ('05 Model)- Senior
|website=Perani's Hockey World
|url-status=live
|archive-url=https://archive.today/20250119155948/https://www.hockeyworld.com/Easton-Synergy-1300C-Hockey-Skates-05-Model-Senior
|archive-date=2025-01-19
|access-date=2025-01-19
}}</ref><ref>{{cite web
|url=https://www.hockeyforum.com/threads/easton-synergy-skates-break-in.34507/
|title=Easton Synergy Skates Break-In?
|website=Hockey Forum
|url-status=live
|archive-url=https://web.archive.org/web/20250119155226/https://www.hockeyforum.com/threads/easton-synergy-skates-break-in.34507/
|archive-date=2025-01-19
|access-date=2025-01-19
}}</ref> [[Shape-memory polymer|Heat molding]] became possible in 2006, with the Easton Synergy 1500C.<ref>{{cite magazine
| author      = <!--Staff writer(s); no by-line.-->
| title       = What's New: Recreation
| url         = https://books.google.com/books?id=dEsX3WG3hEwC&pg=PA26
| magazine    = Popular Science
| volume      = 270
| number      = 1
| date        = January 2007
| page        = 26
| access-date = 2025-01-18
}}</ref><ref>{{cite web
|url=https://sidelineswap.com/gear/hockey/skates/7718248-easton-synergy-1500c-ihs-hockey-skates-size-9-5-e-black-men-skate-ice-sr-wide-w
|title=Easton Synergy 1500C IHS Hockey Skates
|website=Sideline Swap
|url-status=live
|archive-url=https://archive.today/20250119160351/https://sidelineswap.com/gear/hockey/skates/7718248-easton-synergy-1500c-ihs-hockey-skates-size-9-5-e-black-men-skate-ice-sr-wide-w
|archive-date=2025-01-19
|access-date=2025-01-19
}}</ref> Other hockey makers, such as VH Hockey, took it one step further, creating a single, unbroken composite shell that also incorporates the "facing" portion where eyelets are located.<ref name="xinhaidude-carbon-fiber-inline-skates"/> A heat-moldable monocoque shell requires no breaking-in, unlike traditional hockey skates.<ref name="got-hockey-interview-w-scott-van-horne"/>

[[True Temper Sports]] bought VH Hockey in 2016, and started to mass-produce retail hokey skates with heat-moldable monocoque shells, as well as scaling up [[3D scanning]] of feet at retail stores for [[Carbon-fiber reinforced polymer#Vacuum bagging|custom-molded]] True hockey skates,<ref name="got-hockey-interview-w-scott-van-horne">{{cite web
|first1=Dana
|last1=O'Connor
|title=Ep 21 Scott Van Horne - True - Legendary Skate Builder - Got Hockey
|url=https://www.youtube.com/watch?v=s6GAJoJh7VE
|website=Got Hockey
|language=en
|format=video
|date=2023-09-07
}} See transcript for this 45 minute chat with Scott Van Horne.
</ref><ref>{{cite web
|url=https://hockeyworldblog.com/2016/11/22/true-temper-sports-acquires-vh-footwear/
|title=True Temper Sports Acquires VH Footwear: 2016-09-22
|website=Hockey World Blog
|date=22 November 2016
|url-status=live
|archive-url=https://web.archive.org/web/20250119225824/https://hockeyworldblog.com/2016/11/22/true-temper-sports-acquires-vh-footwear/
|archive-date=2025-01-19
|access-date=2025-01-19
}}</ref><ref>{{cite AV media
|title=True Hockey Skate Factory Tour
|url=https://www.youtube.com/watch?v=C_mb4-tL9NA
|via=YouTube
|publisher=Inline Warehouse
|language=en
|format=video
|date=2023-07-26
}} Scott Van Horne showing the manufacturing process of a True hockey skate with a monocoque shell, as specified in VH Footware's US patent 9,656,153.
</ref> leading to inline hockey skates such as the TF9 Roller Skate, and the TF Pro Custom Roller Skate in 2020.<ref name="the-hockeyshop-prod-page-True-TF9">{{cite web
|url=https://www.thehockeyshop.com/products/true-tf9-senior-roller-hockey-skates
|title=TRUE TF9 Senior Roller Hockey Skates
|website=The Hockey Shop
|url-status=live
|archive-url=https://archive.today/20250119220702/https://www.thehockeyshop.com/products/true-tf9-senior-roller-hockey-skates
|archive-date=2025-01-19
|access-date=2025-01-19
}}</ref><ref name="coast-to-coast-prod-page-True-Pro">{{cite web
|url=https://coasthockeyshop.com/products/true-pro-custom-roller-hockey-skate
|title=True Pro Custom Roller Hockey Skate Senior
|website=Coast to Coast Hockey Shop
|url-status=live
|archive-url=https://archive.today/20250119165038/https://coasthockeyshop.com/products/true-pro-custom-roller-hockey-skate
|archive-date=2025-01-19
|access-date=2025-01-19
}}</ref>
{{Clear}}

== Frames ==

[[Image:Inline skate wheels.jpg|thumb|right|upright|Frame and wheels]]

{{Main|Inline skate frame}}

An inline skate frame, sometimes referred to as the "chassis" in certain disciplines such as hockey,<ref name="the-hockeyshop-prod-page-True-TF9"/> serves as the structural link between the [[#Boots|boot]] and the [[#Wheels|wheels]]. It connects to the ground through the wheels mounted on it, and to the skater's foot through the sole of the boot.

=== Frame dimensions ===

{{Main|Inline skate frame#Dimensions}}

"Frame length", also known as [[wheelbase]], refers to the distance between the centers of the first and last wheel axles. In disciplines like [[Inline hockey|hockey]] and [[Freestyle slalom skating|slalom]], skaters use short frames with closely packed wheels to enhance maneuverability and enable fluid footwork. In contrast, [[Inline speed skating|speed skating]] relies on longer frames, which space out the wheels to provide greater stability at high speeds.<ref name="powerslide-download-guides-frames"/>

{{multiple image
 | total_width = 320
 | direction = horizontal
 | image1 = Razors Shift Jeph Howard 2-detached-UFS frame n boot-profile-IMG 6177-bg-FRD.png
 | image2 = Inline skate parts-Boot-Frame n Wheels-PS Tau urban boot-Nexus Rocker 235mm frame-PS Spinner 90mm wheels-Left skate-IMG 3786-IMG 5868-FRD.png
 | footer = Level deck height (UFS) vs. raised heel (Trinity)
}}

"Frame height", "deck height", and "ride height" are related but loosely defined terms in inline skating. All three describe how low a boot can be positioned relative to the ground in a [[#Skate tuning|given setup]], considering the number and size of the wheels. Ideally, a skater wants the boot as close to the ground as possible, while allowing enough clearance between the sole and the wheel tops for free rotation.<ref name="skatingmagic-on-frames-buying-guide"/><ref name="loco-skates-on-frame-mounting"/> All three terms may refer to the distance from the frame's deck to the wheel axle center, excluding wheel size. In other cases, they are defined as sole-to-ground distance, incorporating both the structure of a frame and of actual wheel size.{{efn-ua|name=notes-on-loosely-defined-frame-height|The loosely defined terms "frame height", "deck height", and "ride height" are usually absent from the technical specifications of skates or frames. However, they are frequently used in reviews and buying guides for comparison. In the following articles, the distance from the bottom of a boot (i.e., the sole) to the ground is variously referred to as frame height, deck height, and ride height: [https://web.archive.org/web/20250305231228/https://skatingmagic.com/inline-skate-frame-buying-guide/ Skating Magic archive], [https://web.archive.org/web/20250205030112/https://www.inlinewarehouse.com/fitlc/frames/skate-frame-buying-guide.html Inline Warehouse archive], [https://web.archive.org/web/20241211023024/https://www.cadomotus.com/en/blogs/cadowiki/the-difference-between-hi-lo-and-4x110-setups/ Cadomotus archive], [https://web.archive.org/web/20250120134002/https://www.locoskates.com/blogs/help-articles/frame-mounting-for-inline-skates-explained Loco Skates archive 1], and [https://web.archive.org/web/20241220213905/https://www.locoskates.com/blogs/help-articles/inline-skates-buyers-guide-everything-you-need-to-know Loco Skates archive 2]. Similarly, the distance from the top of a mount (i.e., roughly the sole) to the center of a wheel axle is described as deck height and ride height in these articles: [https://web.archive.org/web/20250305234505/https://atomskates.com/pages/inline-frame-sizing Atom Skates archive] and [https://web.archive.org/web/20250305235116/https://www.locoskates.com/products/ground-control-featherlite-flt4-frames-red-flt4 Loco Skates archive 3]. Only in rare instances, such as on [https://web.archive.org/web/20241204004637/https://www.thisissoul.com/products/ground-control-ufs-featherlite-4-white this product page], does "frame height" actually refer to the physical measurement of the frame itself.}}<ref name="powerslide-download-guides-frames"/><ref name="ricardo-lino-on-trinity-2017"/>

=== Frame rigidity ===

{{Main|Inline skate frame#Rigidity}}

[[File:Rollerblade 2-bg.png|thumb|right|Plastic frames]]

[[File:Inline skate parts-Frame-Nexus Rockerable 235mm frame-PS Spinner 90mm wheels-IMG 5890-FRD.png|thumb|right|Extruded & milled aluminum]]

Frame rigidity is essential for an efficient [[Energy conversion efficiency|transfer of power]] from a skater's foot to the ground. A rigid frame does not suffer from [[Hysteresis|elastic hysteresis]].<ref name="powell-svensson-inline-skating"/>{{rp|18–21}} For this reason, even entry-level inline skates often use [[fiberglass-reinforced plastic]], instead or softer but cheaper plastic to make frames. For a stiffer yet lightweight frame, aircraft-grade [[Aluminium|aluminum]] alloys such as the 6000 and 7000 series are used. Hockey and speed skating often call for [[magnesium]] frames, which are even stiffer and lighter than aluminum. Some speed skaters use [[Carbon-fiber reinforced polymer|carbon fiber]] frames that are the most rigid and lightweight frames available.<ref name="vegter-everything-about-frames"/><ref name="le-roller-en-ligne-on-skate-frame-uses">{{cite web
|url=https://www.rollerenligne.com/materiel/which-skate-frame-for-which-use/
|title=Which skate frame for which use?
|website=Le Roller en Ligne
|date=3 November 2010
|url-status=live
|archive-url=https://web.archive.org/web/20250215031318/https://www.rollerenligne.com/materiel/which-skate-frame-for-which-use/
|archive-date=2025-02-15
|access-date=2025-02-15
}}</ref>

Rigidity of a frame is an important factor in choosing one. However, other considerations, including cost and weight, also influence the decision.<ref name="le-roller-en-ligne-on-manufacturing-of-skate-frames">{{cite web
|url=https://www.rollerenligne.com/materiel/the-manufacturing-processes-of-skate-frames/
|title=The manufacturing processes of skate frames
|website=Le Roller en Ligne
|date=23 November 2007
|url-status=live
|archive-url=https://web.archive.org/web/20250215033904/https://www.rollerenligne.com/materiel/the-manufacturing-processes-of-skate-frames/
|archive-date=2025-02-15
|access-date=2025-02-15
}}</ref> Sometimes, a discipline's needs trump many of these factors. For instance, aggressive skaters exclusively use fiberglass-reinforced plastic frames for their superior performance and consistent friction when [[Aggressive inline skating|grinding]] against all types of surfaces.<ref name="gutman-catching-air-2004"/>{{rp|138}} Some of the most rigid frames, such as those made of carbon fiber, can be too brittle for [[Inline hockey|hockey]]. These frames shatter rather than deform under impact or extreme stress due to their low [[fracture toughness]].<ref name="le-roller-en-ligne-on-anatomy-of-skate-frames">{{cite web
|url=https://www.rollerenligne.com/materiel/anatomy-of-a-skate-frame/
|title=Anatomy of a skate frame
|website=Le Roller en Ligne
|date=6 December 2007
|url-status=live
|archive-url=https://web.archive.org/web/20250215034517/https://www.rollerenligne.com/materiel/anatomy-of-a-skate-frame/
|archive-date=2025-02-15
|access-date=2025-02-15
}}</ref> In addition, some skaters value comfort, which is at odds with rigid frames; increased rigidity transmits all imperfections of the road surface to the skater unattenuated, reducing comfort.<ref name="le-roller-en-ligne-on-aluminum-magnesium-carbon-frames">{{cite web
|url=https://www.rollerenligne.com/materiel/which-material-for-your-skate-frames-magnesium-or-aluminum/
|title=Which material for your skate frames: Magnesium or aluminum?
|website=Le Roller en Ligne
|date=25 January 2011
|url-status=live
|archive-url=https://web.archive.org/web/20250215034730/https://www.rollerenligne.com/materiel/which-material-for-your-skate-frames-magnesium-or-aluminum/
|archive-date=2025-02-15
|access-date=2025-02-15
}}</ref>

=== Rockerable frames ===

{{multiple image
 | direction = vertical
 | width = 170
 | image1 = First Rollerblade brand inline skates with round heel brake-from early 1980s-IMG 5980-Rockerable Frame view 2-FRD.png
 | image2 = Nexus Rockerable 235mm inlne frame and axle bolts-IMG 5900-bg-FRD.png
 | image3 = Endless 90 Trinity inline skate frame-Undercover 110mm wheels-IMG 4095-Rocker annotated-bg-FRD.png
 | caption1 = Rockerable frame: 1980s
 | caption2 = Toggleable axles: 2020
 | caption3 = Pre-rockered: 2025
}}

{{Main|Inline skate frame#Rockerable}}

[[#Rockered setup|Wheel rockering]] can be achieved by using wheels of different [[#Wheel diameter and profile|diameters]], or by using a frame with built-in support for a rockered arrangement of identical wheels. Such rockerable frames may be configured in either a [[#Flat setup|flat setup]] for long-distance skating, or a [[#Rockered setup|banana-rockered setup]] for highly maneuverable disciplines like hockey, with sharp turns and quick footwork.<ref name="rollerblades-dryland-training-1985"/>{{rp|81–86}}<ref name="naomi-grigg-2014"/>{{rp|20–21}}

Some frames are compatible with specialized [[Hardware (mechanical and construction)|hardware]] for quick and reliable switching of [[#Wheel setup|wheel setups]]. These involved the use of frame spacers, axle guides, mounting hole inserts, or axle bolts that fit oblong mounting holes in two ways. Such hardware can be toggled to shift the axle's center between two preset positions.<ref name="miller-get-rolling-2003"/>{{rp|44–45}}{{efn-ua|name=notes-on-brennan-olson-1987-lightning-patent|Brennan Olson's patent application filed in 1987 described key innovations in the 1988 Lightning skate: a single-piece plastic frame with reinforcement bridges, toggleable inserts for mounting hole for rockering (named axle aperture plug in the specification), and wheel hubs each with an interlock rim (named outer annular ring 16P) over which polyurethane is molded to reduce wheel deformation and heat buildup.<ref name="brennan-olson-1987-patent-modern-inline-skates"/>}}

With the advent of mounting standards and easily swappable frames in the 21st century, some inline frames now eschew toggleable hardware in pursuit of reduction in complexity, weight, and number of components. Each brand offers its own [[#Forward lean with a rocker|pre-rockered frame]] with custom axle holes to create a wheel arrangement that it deems optimal.<ref name="naomi-grigg-2014"/>{{rp|20–21}}<ref name="endlessblading-geometry-of-inline-rocker-designs"/>

=== Non-standard frames ===

{{Main|Inline skate frame#Non-standard}}

[[File:USSR inline skate-from 1962-by alextreme-wheels.jpg|thumb|right|upright=0.8|USSR skates (1960s)]]

[[File:Powerslide One Zoom-inline skates-IMG 5832-bottom view-FRD.png|thumb|right|upright=0.8|PS One Zoom (2024)]]

Modern inline skates began as off-season training tools for [[Ice skating|ice skaters]].<ref name="vegter-everything-about-frames"/> [[History of inline skates#Precursors|Early frames]], including those used by the USSR speed skating team in the 1960s, featured adjustable lengths and variable wheel positions to fit different shoe sizes.<ref name="shevelson-golden-days-of-skating-skaters-mag-premier-issue-1990"/> This approach continued in the 1966 Chicago Roller-Blade and [[History of inline skates#Modern inline skates|early 1980s Rollerblade skates]].{{efn-ua|name=chicago-roller-blade-ads}}{{efn-ua|name=olson-1983-rollerblade-with-adjustable-ultimate-frame|See pictures of the new generation of early Rollerblade skates with heel brakes, from [https://history.vintagemnhockey.com/page/show/1136093-minnesota-in-line-hockey-and-history-of-in-line-skates Vintage Minnesota Hockey]: [https://cdn1.sportngin.com/attachments/photo/8217/4572/Rollerblade_Ole_s_Innovative_Sports_Packaging_large.jpg picture], [https://cdn1.sportngin.com/attachments/photo/3264/3697/Blade_Runner_Rollerblades_large.JPG picture], [https://cdn1.sportngin.com/attachments/photo/3262/7119/Rollerblade_Training_Skates_Ad_large.jpg picture] and [https://cdn1.sportngin.com/attachments/photo/8bc0-134049225/Rollerblade_Only_a_Hockey_Player_Can_Understand_Ad_large.jpg picture], archived [https://web.archive.org/web/20230531051534/https://cdn1.sportngin.com/attachments/photo/8217/4572/Rollerblade_Ole_s_Innovative_Sports_Packaging_large.jpg here], [https://web.archive.org/web/20230531051536/https://cdn1.sportngin.com/attachments/photo/3264/3697/Blade_Runner_Rollerblades_large.JPG here], [https://web.archive.org/web/20230531051527/https://cdn1.sportngin.com/attachments/photo/3262/7119/Rollerblade_Training_Skates_Ad_large.jpg here] and [https://web.archive.org/web/20230531051525/https://cdn1.sportngin.com/attachments/photo/8bc0-134049225/Rollerblade_Only_a_Hockey_Player_Can_Understand_Ad_large.jpg here]. These have a refined version of the adjustable frame from the Ultimate Street Skate, and a similar hard boot. These skates witnessed the transition of Scott Olson's company from "Ole's Innovative Sports", to "North American Sports Training Corp.", and finally to "Rollerblade", as attested by marketing materials.<ref name="VMH-history-with-pic-gallery"/>
}} Early inline skates lacked mounting standards. The 1962 USSR skate and 1966 Chicago Roller-Blade fit [[dress shoe]]s with heels, while the 1975 Super Sport Skate, modeled after hockey boots, already had a raised heel mount on the frame.{{efn-ua|name=silver-super-sport-skate-ads-pics}}

Non-standard frames still dominate entry-level skates and are often non-replaceable. Most lack adjustment for [[pronation]] or [[supination]]. Some, like the 2024 Powerslide One Zoom, use [[rivet]]ed frames that cannot be customized.<ref name="vegter-everything-about-frames"/> Outside the entry-level market, most inline skates follow one of three mounting standards: [[#UFS frames|UFS]], [[#165mm and 195mm frames|165mm]], or [[#Trinity frames|Trinity]].<ref name="skatingmagic-on-frames-buying-guide"/><ref name="loco-skates-on-frame-mounting"/> The exception is [[#Hockey|hockey skates]], which still use riveted mounts like ice hockey boots. All hockey skates, from budget to high-end custom models, have proprietary, non-replaceable frames.{{efn-ua|name=inline-hockey-skates-made-by-same-ice-hockey-makers}}

=== 165mm and 195mm frames ===

{{Main|Inline skate frame#165mm and 195mm}}

[[File:Speedskate Hyper-bg removed.png|thumb|right|165mm speed boot]]

In 1974, Inze Bont introduced fiberglass [[ice skate#Racing skates|speed skate]] boots with {{nowrap|165 mm}} mounting holes for attaching adjustable ice blades.<ref name="vegter-everything-about-frames"/> As inline skating grew in the mid-1980s, brands like Darkstar, [[Mogema]], and Raps created frames to fit these boots, establishing the first inline skate mounting standard: the "165mm 2-point" system.<ref name="le-roller-en-ligne-interview-alex-bont"/>

[[File:Rollerblade.jpg|thumb|right|upright=0.8|Rollerblade Twister 80 with a 165mm mount]]

Later known as SSM (Standard Speed Mount),<ref name="bladeville-glossary-terms-rollerblading"/> this standard features a {{nowrap|10 mm}} [[#Heel raise|heel raise]] that enhances power in [[#Striding and gliding|push-offs]] through deeper ankle flexion.<ref name="bladeville-inline-skate-frames"/> The standard does not specify a frame width, mount width or exact mounting locations on the boot.<ref name="vegter-everything-about-frames"/> In practice, Bont boots offer only minimal mounting areas. But compatible and rigid frames can still be secured to a boot with minimal flex, especially with Bont's later [[kevlar]] and [[Carbon-fiber reinforced polymer|carbon]] boots.<ref>{{cite web
|url=https://bont.com/pages/about-us
|title=Bont - About Us - Who we are
|website=Bont
|url-status=live
|archive-url=https://web.archive.org/web/20241126224141/https://bont.com/pages/about-us
|archive-date=2024-11-26
|access-date=2025-02-16
}}</ref> Roces Impala skates brought the 165mm standard outside of [[#Speed|speed skating]] in the mid-1990s, expanding it to [[#Recreational|recreational]], [[#Aggressive|aggressive]], and [[#Urban|slalom]] skating. However, softer [[Shoe#Sole|soles]] in these boots may flex under load, prompting reinforcement with metal plates.<ref name="vegter-everything-about-frames"/>

Originally designed for five small wheels (e.g. 5x80mm), the 165mm layout caused bolt interference when 4x100mm setups with [[#Wheel diameter and profile|larger wheels]] became popular, forcing frames to become [[#Frame dimensions|taller]].<ref name="zecoprzepraszam-inerview-powerside-on-trinity-165mm-195mm"/> To address this, the "195mm 2-point" LSM (Long Speed Mount) was introduced in 2003.<ref name="powerslide-different-mounting-systems"/> It allows longer frames and larger wheels, while retaining the same heel raise, without adding additional height.<ref>{{cite web
|url=https://powerslide.com/blogs/technologies/195-mounting
|title=195 Mounting
|website=Powerslide
|url-status=live
|archive-url=https://web.archive.org/web/20250217185608/https://powerslide.com/blogs/technologies/195-mounting
|archive-date=2025-02-17
|access-date=2025-02-17
}}</ref> This design provides a stable ride at high speeds by maintaining a relatively low [[Center of mass|center of gravity]] in proportion to the longer wheelbase.<ref name="le-roller-en-ligne-on-165mm-195mm-triskates"/><ref name="powerslide-download-guides-frames"/> While LSM is mainly used in speed skating, many frames now include slots to fit both standards.<ref name="inline-warehouse-frame-buying-guide"/>

=== UFS frames ===

{{Main|Inline skate frame#UFS}}

{{multiple image
 | direction = horizontal
 | total_width = 270
 | image1 = K2 Fatty Pro-2nd gen-EU edition-1997-Aggressive Inline Skates-A Schneider-IMG 9500-Soulplate frame n wheels-bg.png
 | image2 = Roces 5th Element-1998-Aggressive Inline Skates-A Schneider-IMG 2834-Soulplate frame n wheels-bg.png
 | caption1 = K2 Fatty Pro
 | caption2 = 5th Element
}}

[[Aggressive inline skating]] gained mainstream attention after its 1995 [[ESPN Inc.|ESPN]] [[X Games]] debut, sparking rapid growth and development of [[#Aggressive|aggressive skates]].<ref name="x-games-history-official-page"/> Released in 1996, the [[K2 Sports|K2]] Fatty was the first skate to integrate the frame into the soulplate, reducing height differences and replacing the traditional two-part platform with a solid rectangular structure.<ref name="bladeville-ufs-universal-frame-system">{{cite web
|url=https://bladeville.com/blog/what-is-ufs-system
|title=What is UFS - Universal Frame System
|date=2022-03-10
|website=Bladeville
|url-status=live
|archive-url=https://web.archive.org/web/20220831003740/https://bladeville.com/blog/what-is-ufs-system
|archive-date=2022-08-31
|access-date=2025-02-21
}}</ref><ref name="back-to-blading-k2-fatty-past-and-now">{{cite AV media
|title=What Happened to the K2 Fatty? // Aggressive Inline Skating
|url=https://www.youtube.com/watch?v=knv-S-OXrL0
|via=YouTube
|publisher=Back to Blading
|language=en
|format=video
|date=2018-10-05
}} See video transcript on discussions on origin of K2 Fatty, prototype/sample of Fatty Pro, and 2018 Fatty.
</ref> In 1998, Roces released the 5th Element, an aggressive skate that combined the soulplate and frame into a single flat unit with no height difference between front and rear. This flat sole improved soul grinds and influenced other skate designs.<ref name="vegter-roces-5th-element-history-n-2020-model">{{cite web
|first1=Ivo
|last1=Vegter
|title=Review: Roces 5th Element
|url=https://www.youtube.com/watch?v=uaEWIBxcBiM
|website=thisissoul.com
|publisher=This is Soul
|language=en
|format=video
|date=2022-05-08
}} See video transcript on history of Roces, relationship to Rollerblade, 1998 Roces 5th Element, and 2020 version of the 5th Element.
</ref>

{{multiple image
 | direction = horizontal
 | total_width = 330
 | image1 = Rene Borel-Salomon-US6648346-2001-UFS mounting standard-patent drawing-FIG 4.png
 | image2 = Razors Shift Jeph Howard 2-detached-UFS frame n boot-soulplate view-IMG 6193-bg-FRD.png
 | footer = UFS patent drawing (left). Razors Shift - UFS boot and frame (right).
}}

In 1999, [[Salomon Group|Salomon]], USD, Razors, Kizer, 7XL/Able, and Fifty/50 developed the Universal Frame System (UFS), a standardized mounting system for aggressive skates. It used a flat rectangular surface {{nowrap|41 mm}} wide with two holes spaced {{nowrap|167 mm}} apart, aligning with the trend of flat soulplates. Salomon's 2001 [[Aaron Feinberg]] Pro Model was the first skate to feature UFS and quickly became a popular industry standard.<ref name="back-to-blading-origin-of-UFS-and-mounting-standards"/><ref name="le-roller-en-ligne-on-le-norme-UFS">{{cite web
|url=https://www.rollerenligne.com/materiel/la-norme-ufs-universal-frame-system/
|title=La norme UFS (Universal Frame System)
|date=2018-08-22
|website=Le Roller en Ligne
|language=fr
|url-status=live
|archive-url=https://web.archive.org/web/20250222021127/https://www.rollerenligne.com/materiel/la-norme-ufs-universal-frame-system/
|archive-date=2025-02-22
|access-date=2025-02-22
}}</ref><ref name="us-patent-6648346-Borel-Salomon-UFS-standard">{{Cite patent
|country=US
|number=6648346
|fdate=2001-02-09
|pubdate=2003-11-18
|gdate=2003-11-18
|title=Frame for a sport article (UFS standard)
|inventor1-first=René
|inventor1-last=Borel
|assign1=Salomon SAS
}}</ref>

Unlike other mounting systems of the time, UFS eliminated built-in [[#Heel raise|heel raise]], positioning the heel level with the toes for the first time. However, most brands followed Salomon's lead in incorporating a thick shock absorber at the heel. This provided better impact support for hard landings from high jumps, but accidentally reintroduced a small amount of heel raise.<ref name="bladeville-ufs-universal-frame-system"/><ref name="vegter-everything-about-frames-companion-video">{{cite web
|title=Into Detail: About Frames
|url=https://www.youtube.com/watch?v=3b69Su4Nx-o
|website=www.thisissoul.com
|publisher=This Is Soul
|language=en
|format=video
|date=2020-10-18
}} This is the companion video of the article on "Everything about Frames".
</ref>

=== Trinity frames ===

{{Main|Inline skate frame#Trinity}}

[[File:Powerslide Reign Ares hybrid skates-on Ego SL frame and Trident 100mm wheels-side-view-IMG 4721-bg-FRD.png|thumb|right|upright=0.8|A Trinity boot & frame]]

The [[#165mm and 195mm frames|165mm standard]], originally from speed skating, has dominated since the mid-1990s, except in [[#Aggressive|aggressive]] ([[#UFS frames|UFS]]) and [[#Hockey|hockey]] (riveted) skates. But its small mount area can cause frame wobble on boots without stiff soles or reinforced platforms.<ref name="vegter-everything-about-frames"/> As larger wheels became popular, 165mm frames adapted with taller designs or altered wheel placement to fit bigger wheels. Some raised frame height, reducing stability,<ref name="bladeville-inline-skate-frames"/> while others downsized or shifted middle wheels to avoid bolt interference.<ref name="rockin-frames-on-MIX4-and-165mm-mid-wheel-reductions"/> Some brands shifted mount platforms, leading to front-back centering issues when mixing boots and frames.<ref name="zecoprzepraszam-inerview-powerside-on-trinity-165mm-195mm"/> Introduced in 2003, the [[#165mm and 195mm frames|195mm standard]] supported larger wheels without raising frame height or altering wheel placement.<ref name="powerslide-different-mounting-systems"/> However, its extended front-to-back spacing exceeded the optimal "heel-to-ball" length, requiring ultra-stiff soles not found outside the [[Inline speed skating|speed skating]] market until the late 2010s, limiting adoption to [[Carbon-fiber reinforced polymer|carbon-fiber]] speed speed boots.<ref name="cadomotus-on-165mm-195mm-boots-on-ice-blades"/><ref name="brannock-heel-to-ball-support-for-foot">{{cite web
|url=https://brannock.com/pages/instructions-fitting-tips
|title=Why Heel-to-Ball Is Essential
|website=The Brannock Device Company
|url-status=live
|archive-url=https://web.archive.org/web/20250129180026/https://brannock.com/pages/instructions-fitting-tips
|archive-date=2025-01-29
|access-date=2025-03-02
}}</ref><ref name="kai-nin-bottom-structure-inline-shoes-patent-2008">{{Cite patent
|country=WO
|status=application
|number=2010051657
|fdate=2008-11-10
|pubdate=2010-05-14
|title=Bottom structure for inline roller skate shoes
|inventor1-first=Kai Nin
|inventor1-last=So
}}</ref>

[[File:Trinity mounting-Boot showing three mounting platforms-IMG 3878-bg-FRD.png|thumb|right|upright=0.8|Trinity mounts]]

In 2016, Powerslide introduced the Trinity mounting system to support [[#Wheel setup|modern wheel setups]] while addressing the limitations of the 165mm and 195mm standards.<ref name="powerslide-launching-trinity-boots-and-frames-2016">{{cite AV media
|first1=Matthias
|last1=Knoll
|first2=Jürgen
|last2=Pfitzner
|first3=Scott
|last3=Arlidge
|title=Trinity Mount - The next level
|url=https://www.youtube.com/watch?v=GDC_ITPAb44
|via=YouTube
|publisher=Powerslide
|language=en
|format=video
|date=2016-07-27
}} Powerslide introduced Trinity for all skating disciplines.
</ref> Unlike two-point systems, Trinity uses ''three mounts''. The two front bolts are offset, placed beside the centerline to allow front wheels to sit closer to the sole.<ref name="powerslide-matthias-knoll-Trinity-patent-2017">{{Cite patent
|country=US
|number=10524533
|pridate=2015-01-28
|fdate=2017-07-21
|pubdate=2020-01-07
|gdate=2020-01-07
|title=Roller skate system having a rail and a boot
|inventor1-first=Matthias
|inventor1-last=Knoll
|assign1=Powerslide GmbH
}}</ref> The rear mount, located under the heel, is raised by {{nowrap|10 mm}} to clear the rear wheels and create a [[#Heel raise|heel raise]] similar to the 165mm standard. The three bolts form a triangular layout measuring {{nowrap|150 mm}}, {{nowrap|135 mm}}, and {{nowrap|55 mm}}.<ref name="xinhaidude-ps-trinity-reign-as-big-wheel-urban-skate"/> This design aligns with foot anatomy for improved heel-to-ball support and structural stability.<ref name="powerslide-download-guides-frames"/><ref name="brannock-heel-to-ball-support-for-foot"/>

{{multiple image
 | direction = vertical
 | width = 200
 | image1 = Trinity mounting-specs and dimensions and measurements-View Perspective-IMG 6202-annotated-FRD.jpg
 | image2 = Trinity mounting-specs and dimensions and measurements-View Ortho Top-IMG 6231-annotated-FRD.jpg
 | image3 = Trinity mounting-specs and dimensions and measurements-View Ortho Side-IMG 6241-annotated-FRD.jpg
 | caption3 = Trinity specifications
}}

A Trinity frame typically wobbles less than 165mm or 195mm frames on similarly stiff boots. Unlike 165mm setups, which rely on the sole acting as a [[cantilever]] around central bolts, Trinity distributes support across the full width of the [[Ball (foot)|ball of the foot]], similar to a hockey blade holder. This wider support reduces cantilever [[Stress (mechanics)|stress]], improving power transfer and edge support.<ref name="inlinex-trinity-mounting">{{cite web
|url=https://inlinex.com.sg/blogs/news/trinity-three-point-mount
|title=Trinity Three Point Mount
|first1=Adam
|last1=Choong
|date=2018-05-15
|website=Inlinex
|url-status=live
|archive-url=https://web.archive.org/web/20250303031629/https://inlinex.com.sg/blogs/news/trinity-three-point-mount
|archive-date=2025-03-03
|access-date=2025-03-03
}}</ref><ref name="powerslide-trinity-vs-195mm-2022">{{cite AV media
|url=https://www.youtube.com/watch?v=R0sDnLquuiY
|first1=Pascal
|last1=Briand
|title=Trinity vs 195 Mounting - PS live stream
|date=2022-03-22
|via=YouTube
|publisher=Powerslide
|language=en
|format=video
|url-status=live
|archive-url=https://web.archive.org/web/20240323154657/https://www.youtube.com/watch?v=R0sDnLquuiY
|archive-date=2024-03-23
|access-date=2025-05-04
}} Pascal talks about Trinity's development history and specifications. He compares Trinity mounting to 195mm mounting, including the wide front mounts for better control and pushes.
</ref>

A Trinity frame typically has a lower front [[#Frame dimensions|mount height]] than its 165mm counterpart when using the same wheel setup. This is because the front mount of a Trinity frame can be positioned significantly lower than the tops of the front wheels due to its open centerline, allowing the front of the boot to be moved as close to the ground as the front wheels allow. This lowers the skate's center of gravity, improving control and stability.<ref name="ricardo-lino-on-trinity-2017"/>

=== Heel brakes and toe stops ===

{{Main|Inline skate frame#Heel brakes and toe stops}}

[[File:Heel brake.jpg|thumb|right|upright|Heel brake]]

[[File:Inline figure skate.jpg|thumb|upright|Toe stop]]

A heel brake is a hard [[Natural rubber|rubber]] stopper attached to the back of the frame that lets skaters stop by lifting their toes and pressing the brake to the ground. It is especially important for beginners, offering a simple way to stop quickly and control downhill speed. [[#Recreational|Recreational and fitness]] skates usually include one brake, mountable on either skate, with most righthanded skaters choosing the right.<ref name="fried-cassorla-inline-ultimate-guide-1995"/>{{rp|25–26}}

Heel brakes can interfere with advanced techniques like [[Crossover (figure skating)|crossover turns]], which are essential in [[Inline hockey|hockey]] and [[Inline speed skating|speed]] skating. They also hinder [[Freestyle slalom skating|freestyle slalom]] tricks and [[Aggressive inline skating|aggressive grinds]]. As a result, skates made for racing, hockey, slalom, and aggressive skating typically do not include a heel brake.<ref name="inlineskates-types-of-skates"/><ref name="powell-svensson-inline-skating"/>{{rp|30–38}} Some [[#Urban|urban skates]] include an unattached brake, while others cannot support one at all. Many experienced skaters remove heel brakes after learning other stopping methods, such as the "T-stop", which uses friction from dragging one skate behind the other. However, these techniques [[#Wheel rotation|wear down wheels]], so some skaters prefer slalom moves and controlled turns to avoid obstacles and reduce wear.<ref name="powell-svensson-inline-skating"/>{{rp|87–96,101–114}}<ref name="naomi-grigg-2014"/>{{rp|24}}

[[Inline figure skating|Inline figure skates]] are unique among inline designs in that they use a "toe stop" instead of a heel brake. Toe stops are essential for performing many [[artistic roller skating]] moves and jumps.<ref name="museum-of-roller-skating-history-of-roller-skating-1997"/>{{rp|22–23}}

== Wheels ==

{{Main|Inline skate wheel}}

=== Polyurethane wheels ===

{{Main|Inline skate wheel#Polyurethane}}

{{multiple image
 | direction = horizontal
 | total_width = 300
 | image1 = Aggressive Inline Skate-Gawds-Symetrics-Dead Wheels-Bottom view-by IG Simply Vic-bg rotated.png
 | image2 = Powerslide Reign Ares hybrid skates-on Ego SL frame and Trident 100mm wheels-side-view-IMG 4721-bg-FRD.png
 | caption1 = Small & hard wheels
 | caption2 = large & soft wheels
}}

{{multiple image
 | total_width = 300
 | direction = horizontal
 | image1 = Amsterdam - Vondelpark - 1466.jpg
 | image2 = Ricossa Alice (Style Slalom) - cropped.jpg
 | footer = Rebound improves performance
}}

Modern inline wheels are made of [[polyurethane]] (also PU or urethane), a versatile [[elastomer]] that [[#Precursors|transformed skating]].<ref name="vegter-everthing-about-wheels"/><ref>{{cite web
|url=https://gallaghercorp.com/urethane-vs-polyurethane/
|title=Urethane vs. Polyurethane
|website=Gallagher Corporation
|url-status=live
|archive-url=https://web.archive.org/web/20250309011902/https://gallaghercorp.com/urethane-vs-polyurethane/
|archive-date=2025-03-09
|access-date=2025-03-09
}} Quote: "when discussing industrial applications, urethane and polyurethane are essentially the same material. The terms are used interchangeably, and there is no functional difference between them."
</ref> It can be [[Polyurethane#Manufacturing|molded]] into any shape and customized for color, [[#Wheel hardness and deformation|hardness]], [[Friction#Static friction|grip]], and [[Elasticity (physics)|elasticity]], enabling specialized wheels for various skating disciplines.<ref name="le-roller-en-ligne-on-inline-wheels"/>{{efn-ua|name=ricardo-lino-with-tony-gabriel-tour-wheel-factory-notes|Ricardo Lino toured the factory floor of Aend Industries, a polyurethane wheel factory, with co-owner Tony Gabriel. Discussions cover all aspects of wheel-making, including history of the company, co-ownership with Neil Piper, machines bought from Tom Peterson, brands they OEM for, injection molding of hubs (cores), trimming of hubs, polyurethane coloring, urethane bonding, dual-density urethane, hardness vs grippiness, hardness vs profile, heating of urethane before pouring, casting urethane into molds, baking after casting, cutting/shaving wheels to final profile, quality control, washing, printing, and packaging.<ref name="ricardo-lino-with-tony-gabriel-tour-wheel-factory">{{cite AV media
|url=https://www.youtube.com/watch?v=GW8Hfj6TRDk
|first1=Ricardo
|last1=Lino
|title=This Factory Makes the Best Wheels for Inline & Quad Skating, Skateboarding & Scooters
|date=2022-06-23
|via=YouTube
|language=en
|format=video
}} See video transcript for a tour of factory floor and discussions on all aspects of wheel-making.
</ref>}}<ref name="science-channel-how-its-made-skateboard-wheels-molding-polyurethane-wheels">{{cite AV media
|url=https://www.youtube.com/watch?v=2OeJdvl3fig
|title=How It's Made: Skateboard Wheels
|date=2020-01-09
|via=YouTube
|language=en
|format=video
}}</ref> Polyurethane offers high elasticity, or [[#Wheel rebound|wheel rebound]], without compromising other properties. This rebound helps convert [[#Striding and gliding|stride]] energy into acceleration, benefiting all types of inline skating.<ref name="gallaghercorp-polyurethane-resilience-elasticity-rebound"/>{{efn-ua|name=gallaghercorp-rebound-is-not-hardness|1=See table in the Gallagher article showing polyurethane compounds with varying hardness from 60A to 95A and varying rebound values (Bayshore Resilience) from 25% to 60%, with no correlations. A [https://www.youtube.com/watch?v=mjV1l7kt2JI YouTube video] ([https://web.archive.org/web/20250224181501/https://www.youtube.com/watch?v=mjV1l7kt2JI archived]) from the article demonstrates "polyurethane resilience" tests (yet another name for Bayshore Resilience) showing two balls with the same hardness, but opposite rebound values. At 0:41, an inline skate wheel with high rebound was shown bouncing off the floor.<ref name="gallaghercorp-polyurethane-resilience-elasticity-rebound"/>}}<ref name="powell-svensson-inline-skating"/>{{rp|24–26}}

Before polyurethane, [[roller skates]] and [[skateboard]]s used "composition wheels" made from [[clay]] or [[Natural rubber|rubber]] mixed with [[fiber]]s.<ref name="raybestos-composition-wheel-patent-1953">{{Cite patent
|country=US
|number=2664317
|fdate=1951-04-11
|pubdate=1953-12-29
|gdate=1953-12-29
|title=Composition roller skate wheel
|inventor1-first=Glynn
|inventor1-last=Thomas
|inventor2-first=John W
|inventor2-last=Cleever
|assign1=Raybestos Manhattan Inc
}}</ref>{{efn-ua|1=Roller Derby made clay composition wheels in the 1960s for their "sidewalk surfboards" (skateboards).<ref>{{cite web
|url=https://www.museumofplay.org/blog/sidewalk-surfing-the-gnarly-history-of-skateboarding-part-i-1940s-to-1972/
|title=Sidewalk Surfing: The Gnarly History of Skateboarding Part I (1940s to 1972)
|date=2018-06-07
|first1=Tara
|last1=Winner
|website=The Strong - National Museum of Play
|url-status=live
|archive-url=https://web.archive.org/web/20250316165159/https://www.museumofplay.org/blog/sidewalk-surfing-the-gnarly-history-of-skateboarding-part-i-1940s-to-1972/
|archive-date=2025-03-16
|access-date=2025-03-16
}}</ref><ref>{{cite web
|url=https://overplywood.wordpress.com/2013/02/28/mains-skateboard-collection-and-the-paul-conibear-ramprocker/
|title=Main's skateboard collection and the Paul Conibear Ramprocker.
|date=2013-02-28
|website=Overplywood - The History of Skateboarding in Swansea
|url-status=live
|archive-url=https://web.archive.org/web/20250316163226/https://overplywood.wordpress.com/2013/02/28/mains-skateboard-collection-and-the-paul-conibear-ramprocker/
|archive-date=2025-03-16
|access-date=2025-03-16
}}</ref> The same wheels were used in their Royal Sidewalk line of roller skates as late as 1974 ([https://web.archive.org/web/20220422040717/https://metvcdn.metv.com/56GtX-1443477523-blog-18.jpg archived catalog page]). By 1978, however, the same Royal Sidewalk line adopted polyurethane wheels under the brand Fireball ([https://web.archive.org/web/20250316181818/https://christmas.musetechnical.com/ShowCatalogPage/1978-Sears-Christmas-Book/0436 archived catalog page]). See archived entry and images of this Etsy listing showing a pair of Royal Sidewalk skates with these clay wheels: [https://web.archive.org/web/20250316163216/https://www.etsy.com/listing/1067326122/vintage-blue-the-royal-official-roller?show_sold_out_detail=1&ref=nla_listing_details listing page], [https://web.archive.org/web/20250316163350/https://i.etsystatic.com/7671864/r/il/548df3/3363673243/il_1588xN.3363673243_kaxv.jpg image 1], and [https://web.archive.org/web/20250316163606/https://i.etsystatic.com/7671864/r/il/bf1893/3315980316/il_1588xN.3315980316_2mbv.jpg image 2].}}<ref name="museum-of-roller-skating-history-of-roller-skating-1997"/>{{rp|20–22}} In the early 1970s, roller skaters tested polyurethane wheels but found them too grippy and slow for [[Roller rink|wooden rink floors]], where composition wheels worked better. By the mid-1970s, skateboarders repurposed polyurethane wheels from roller skates, shaving them to fit. Their elasticity improved rides on rough surfaces and helped revive [[skateboarding]] after its decline in the late-1960s.<ref>{{cite web
|url=https://www.chicagoskates.com/pages/timeline
|title=Chicago Skates Timeline
|website=Chicago Skates (Chicago Roller Skates)
|url-status=live
|archive-url=https://web.archive.org/web/20240916084705/https://www.chicagoskates.com/pages/timeline
|archive-date=2024-09-16
|access-date=2025-03-08
}}</ref><ref name="washingtonpost-reinvention-of-wheel-2004"/><ref name="custompolyurethane-polyurethane-skateboard-wheels">{{cite web
|url=https://custompolyurethane.co.uk/blog/polyurethane-skateboard-wheels/
|title=Are Polyurethane Skateboard Wheels Good?
|date=2022-08-24
|website=Custom Moulded Polyurethane
|url-status=live
|archive-url=https://web.archive.org/web/20250308182122/https://custompolyurethane.co.uk/blog/polyurethane-skateboard-wheels/
|archive-date=2025-03-08
|access-date=2025-03-08
}}</ref>

In the early 1980s, Scott Olson similarly [[History of inline skates#Modern inline skates|repurposed polyurethane wheels]] from roller skates, shaving down tens of thousands to fit the skates sold by his company, Ole's Innovative Sports – later known as [[Rollerblade]]. The same qualities that made polyurethane wheels ideal for skateboarding, such as durability, impact resistance, and a smooth ride, also benefited inline skating. This innovation helped bring inline skating out of obscurity and transform it into a popular outdoor sport during the 1980s.<ref name="bernstein-minnesota-hockey-inline"/><ref name="MIA-olson-inventive-impulse"/><ref name="shevelson-golden-days-of-skating-skaters-mag-premier-issue-1990"/><ref name="le-roller-en-ligne-on-inline-wheels"/>

=== Wheel structure ===

{{Main|Inline skate wheel#Structure}}

[[File:Wheel assembly cross section-Bearings Spacer installed into hub with axle-Inline skates-Side view-Bearings Not Preloaded-IMG 7773-bg-FRD.png|thumb|right|upright=0.8|Wheel cross section]]

Modern inline wheels consist of two main components: an outer polyurethane tire, shaped like a [[Doughnut|donut]], and an inner plastic hub, also known as a "core". The hub features a hollow center designed to accommodate a spacer and two [[#Bearings|ISO 608 ball bearings]]. Made of [[Plastic|hard plastic]], the hub securely holds the bearings in place through a [[friction fit]] - something the softer polyurethane tire cannot achieve. On the other hand, the soft polyurethane tire is able to [[#Wheel hardness and deformation|deform upon ground contact]], cushioning the landing and gripping the ground.<ref name="brennan-olson-1987-patent-modern-inline-skates"/>{{efn-ua|name=ricardo-lino-with-tony-gabriel-tour-wheel-factory-notes}}<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/>

{{multiple image
 | direction = horizontal
 | total_width = 380
 | image1 = Brennan J Olson-US4909523A-1990-Inline roller skate-Patent Drawing-FIG 5 6-urethane tire interlocked with plastic hub.png
 | image2 = Rollerblade-Lightning TRS-Team Rollerblade Series-1988-IMG 5722-bottom view-FRD.png
 | footer = Polyurethane tire molded over a plastic hub - 1988 Rollerblade Lightning patent (left) and skate (right)
}}

From the 1910s to the 1970s, many wheeled skates served as [[History of inline skates#Precursors|precursors to modern inline skates]]. Most of these early skates featured small wheels made of rubber or rubber reinforced with fibers, often with relatively simple constructions.<ref name="Gordon-Ware-patent-US3287023A"/><ref name="maury-silver-tandem-skate-1975"/> In the 1980s, Rollerblade collaborated with [[Kryptonics (company)|Kryptonics]] to develop polyurethane wheels for inline skates. The inline industry adapted plastic hub innovations from [[roller skates]], integrating them into inline wheels. These wheels were [[Polyurethane#Manufacturing|manufactured]] by placing a plastic hub at the center of a [[Molding (process)|mold]] and then pouring molten [[polyurethane]] around it. The liquid polyurethane flowed into cavities and holes in the hub before settling. As it cooled and solidified, it formed a secure interlock with the hub.{{efn-ua|name=notes-on-brennan-olson-1987-lightning-patent}}{{efn-ua|name=kryptonic-rollerblade-wheel-collab-1980s|
Page 79 of Skaters magazine from 1990 features a Kryptonics ad showing the cross section of a Kryptonics wheel with polyurethane molded over a hub through holes in its interlock rim. Page 77 of the same 1990 Skaters magazine features a Rollerblade ad stating that Kryptonics is the official wheel supplier for rollerblade skates.<ref name="skaters-mag-premier-issue-1990-on-getting-started-on-inlines"/>}}<ref name="science-channel-how-its-made-skateboard-wheels-molding-polyurethane-wheels"/>

=== Wheel hubs ===

{{multiple image
 | direction = horizontal
 | total_width = 260
 | image1 = Lloyd Gerhardt Keleny-US5897170A-1999-Inline skate wheel-Patent Drawing-FIG 2.png
 | image2 = Revision Flex Hockey Wheels-80mm-Firm-76A-IMG 6339-backlit-bg-FRD.png
 | footer = Clear polyurethane tire molded over interlock vanes of a plastic hub
}}

{{multiple image
 | direction = horizontal
 | total_width = 260
 | image1 = Cross sectional view-Labeda Polyurethane inline skate wheel-cut in half-80mm 85A-Composition-IMG 6393-IMG 6359-IMG 6366-bg-FRD.png
 | image2 = Ceasura wheel 2-3-rorated-bg removed.png
 | footer = Chemically-bonded interlock rim (left) vs. mechanical interlock (right)
}}

{{Main|Inline skate wheel#Hub}}

The outer rim of a wheel hub, known as the "interlock", is buried within the polyurethane tire. Unless the tire is made from clear urethane, this rim remains hidden from view. Beyond mechanically securing the tire to the hub, the interlock rim also enhances the wheel's overall [[Structural analysis|structural rigidity]].{{efn-ua|name=brennan-olson-1987-patent-notes-on-wheel-structure|Brennan Olson's 1987 patent described wheels with polyurethane poured over a hub with an interlock rim (outer rigid ring 46), and showed drawings of the same.<ref name="brennan-olson-1987-patent-modern-inline-skates"/>}}{{efn-ua|name=kryptonic-rollerblade-wheel-collab-1980s}}<ref name="powerslide-download-guides-wheels"/> Some manufacturers apply a [[Solvent bonding|bonding agent]] to the hub before pouring the polyurethane, creating a [[chemical bond]] that reduces reliance on mechanical interlocking. Others use [[polyurethane]]-blended [[plastic]] hubs that bond chemically with the polyurethane tire during [[Polyurethane#Manufacturing|molding]].{{efn-ua|name=ricardo-lino-with-tony-gabriel-tour-wheel-factory-notes}}<ref name="hockey-office-brand-faqs-labeda">{{cite web
|url=https://www.hockeyoffice.com/information-for-brands-and-products-ice-hockey/faq-manufaktur/
|title=Hockey brands faq - Labeda
|website=Hockey Office
|url-status=live
|archive-url=https://web.archive.org/web/20250329162257/https://www.hockeyoffice.com/information-for-brands-and-products-ice-hockey/faq-manufaktur/
|archive-date=2025-03-29
|access-date=2025-03-29
}}</ref>

The visible hub size varies with wheel dimensions and skating discipline. In small [[#Aggressive|aggressive wheels]], the hub is just a thin ring housing the [[#Bearings|bearings]]. In contrast, {{nowrap|82 mm}} [[#Speed|racing wheels]] from the 1990s had hubs taking up nearly half the diameter. By the 2020s, 110 to {{nowrap|125 mm}} wheels feature hubs that occupy most of the wheel's diameter.<ref name="joyner-inline-hockey-1995"/>{{rp|19–24}}<ref name="powell-svensson-inline-skating"/>{{rp|26–27}}<ref name="skatepro-complete-guide-to-inline-wheels">{{cite web
|url=https://www.skatepro.com/en-us/a15.htm
|title=Wheels for Inline Skates - A Complete Guide
|website=SkatePro
|url-status=live
|archive-url=https://web.archive.org/web/20250131235431/https://www.skatepro.com/en-us/a15.htm
|archive-date=2025-01-31
|access-date=2025-03-27
}}</ref>

{{multiple image
 | direction = horizontal
 | image1 = Rollerblade 303 70mm 85A hubless inline skate wheels by Kryptonics ca 1980s-608ZZ TMK bearings-IMG 6726-bg-FRD.png
 | image2 = Razors Shift Pro Jeph Howard 2 60mm 90A aggressive wheel w bearings-IMG 6607-bg-FRD.png
 | image3 = Roces Impala 2023 Lightspeed Fairy Floss 70mm 84A inline skate wheel w bearings-IMG 6671-bg-FRD.png
 | width1 = 91
 | width2 = 78
 | width3 = 91
 | footer = Hubless (no core), closed core & open
}}

A wheel's [[volume]] grows with the square of its [[#Wheel diameter and profile|diameter given fixed width]]. Large solid wheels would be too heavy for inline skating, so designers adopted [[Baby transport#Strollers|stroller]] wheel concepts, using lightweight spoked hubs with interlock rims to hold the tire. These "spoked hubs", or "open cores", have an outer rim connected to the [[#Bearing alignment|bearing housing]] by spokes. "Full hubs", or "closed cores", are solid discs with no visible separation. "Semi-open cores" fall in between, with solid discs and small hollows drilled to reduce weight.<ref>{{Cite patent
|country=US
|number=4447093
|fdate=1982-08-09
|pubdate=1984-05-08
|gdate=1984-05-08
|title=Wheel
|inventor1-first=Joel C.
|inventor1-last=Cunard
|inventor2-first=William H.
|inventor2-last=Ziegler
|assign1=Brown Group Recreational Products Inc
}}</ref><ref name="le-roller-en-ligne-on-inline-wheels"/>

Spoked cores are generally lighter than full cores but may offer reduced rigidity and structural integrity. Aggressive skaters prefer small wheels with robust full cores for durability during jumps and landings. Speed and marathon skaters use large wheels with spoked hubs, which allow air to circulate around the hub, and [[Air cooling|help cool]] the bearings. Without adequate [[heat dissipation]], the polyurethane tire may soften, increasing [[#Wheel hardness and deformation|deformation]] during rolling and potentially leading to separation from the hub.<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/><ref name="brennan-olson-1987-patent-modern-inline-skates"/><ref name="inlineskates-buying-guide-inline-skate-wheels">{{cite web
|url=https://www.inlineskates.com/Buying-Guide-for-Inline-Skate-Wheels/buying-guide-5-3-2013,default,pg.html
|title=Buying Guide for Inline Skate Wheels
|first1=Steve
|last1=Kopitz
|website=Inline Skates
|url-status=dead
|archive-url=https://web.archive.org/web/20210805202216/https://www.inlineskates.com/Buying-Guide-for-Inline-Skate-Wheels/buying-guide-5-3-2013,default,pg.html
|archive-date=2021-08-05
|access-date=2025-04-04
}}</ref>

=== Wheel diameter and profile ===

[[File:Inline skate wheels-Common profiles and diameters-2025.svg|thumb|right|Common sizes and profiles]]

{{Main|Inline skate wheel#Diameter and profile}}

Inline skate wheels in the 2020s range from {{nowrap|55 mm}} to {{nowrap|125 mm}} in "wheel diameter", but the "wheel width" remains standardized at {{nowrap|24 mm}}.<ref name="vegter-everthing-about-wheel-diameter">{{cite web
|url=https://www.thisissoul.com/blogs/hardware-insights/everything-about-wheel-diameter
|first1=Ivo
|last1=Vegter
|title=Everything about wheel diameter
|website=This Is Soul
|date=3 January 2023
|url-status=live
|archive-url=https://web.archive.org/web/20250404023645/https://www.thisissoul.com/blogs/hardware-insights/everything-about-wheel-diameter
|archive-date=2025-04-04
|access-date=2025-04-04
}} Also reference the companion video shown in the article.
</ref><ref name="powerslide-download-guides-wheels"/> Frames are built for specific [[#Wheel setup|wheel setups]], each fitting a set number of wheels of certain diameters, yet all assume a {{nowrap|24 mm}} "hub width".<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/><ref name="usenet-chen-FAQ-inline-wheels"/> "Wheel profile" describes the shape of the contact surface when viewed head-on. Although any diameter can be matched with any profile, certain combinations work better for specific skating styles.<ref name="liveabout-carlesa-williams-wheels-101"/><ref name="vegter-everthing-about-wheel-profile">{{cite web
|url=https://www.thisissoul.com/blogs/hardware-insights/everything-about-wheel-profile
|first1=Ivo
|last1=Vegter
|title=Everything about wheel profile
|website=This Is Soul
|date=3 January 2023
|url-status=live
|archive-url=https://web.archive.org/web/20250404030250/https://www.thisissoul.com/blogs/hardware-insights/everything-about-wheel-profile
|archive-date=2025-04-04
|access-date=2025-04-04
}} Also reference the companion video shown in the article.
</ref>

{{multiple image
 | direction = horizontal
 | image1 = Razors Shift Pro Jeph Howard 2 60mm 90A aggressive wheel w bearings-IMG 6607-bg-FRD.png
 | image2 = Razors Shift Pro Jeph Howard 2 60mm 90A aggressive wheel w bearings-IMG 6615-bg-FRD.png
 | total_width = 150
 | footer = Flatish ({{nowrap|60 mm}})
}}

"Small" wheels in [[#Aggressive|aggressive skates]], typically 55 to {{nowrap|64 mm}} in diameter, often have a "flat" contact profile resembling a rounded rectangle like [[Tire#Automotive|car tires]].<ref name="inlineskates-buying-guide-inline-skate-wheels"/> This shape provides strong [[#Wheel hardness and deformation|grip]] and stable upright rolling.<ref name="vegter-everthing-about-wheel-profile"/> While flat profiles were popular in the 1990s, modern aggressive skaters increasingly favor slightly rounder profiles for better balance between stability and maneuverability.<ref name="skatepro-aggressive-skate-wheels">{{cite web
|url=https://www.skatepro.com/en-us/c44.htm
|title=Aggressive Skate Wheels
|website=SkatePro
|url-status=live
|archive-url=https://web.archive.org/web/20250405010549/https://www.skatepro.com/en-us/c44.htm
|archive-date=2025-04-05
|access-date=2025-04-05
}}</ref>

{{multiple image
 | direction = horizontal
 | image1 = Labeda Gripper Asphalt 80mm 85A inline skate wheel-IMG 6707-bg-FRD.png
 | image2 = Round profile and edging angles-Labeda inline skate wheel-80mm 85A-IMG 6359-FRD.png
 | total_width = 290
 | footer = Round profile ({{nowrap|80 mm}}) & edging angles
}}

Most inline wheels are "medium-sized" with a "round" profile, since skaters often tilt their skates rather than always keeping them fully upright. Many techniques involve [[#Edging and turning|edging]], or skating on the wheel sides, which requires a consistent [[Contact area|contact surface]] at various angles.{{efn-ua|name="outside-inside-edges-terms"|
Inline skating adopts the terms "outside edge" and "inside edge" from ice skating, even though inline wheels lack the sharp dual edges of ice blades. The outside edge refers to the side of the wheel facing away from the skater's body, while the inside edge is the side facing inward.<ref name="rollerblades-dryland-training-1985"/>{{rp|27–31,41–42,49–52}}
}}<ref name="skaters-mag-premier-issue-1990-on-quad-vs-inline"/> Round profiles support this, even if the contact area is smaller than that of flat wheels. [[#Hockey|Hokey]] and [[#Urban|freestyle slalom]] skates often use round-profile wheels up to {{nowrap|80 mm}} in diameter.<ref name="liveabout-carlesa-williams-wheels-101"/><ref name="powerslide-download-guides-wheels"/>

{{multiple image
 | direction = horizontal
 | image1 = Undercover Team Blank 110mm 86A inline skate wheel with Bones REDS bearings-IMG 4971-bg-FRD.png
 | image2 = Bullet profile-striding and gliding angles-Undercover inline skate wheel-110mm 86A-IMG 6784-FRD.png
 | total_width = 300
 | footer = Bullet profile ({{nowrap|110 mm}}) & striding/gliding
}}

At the opposite end of the spectrum from the flat profile is the "bullet" profile, also known as the pointy, thin, narrow, or elliptical profile. It is common in "large" wheels from 90 to {{nowrap|125 mm}} and often found in [[#Speed|speed skates]].<ref name="miller-get-rolling-2003"/>{{rp|51–52}}<ref name="le-roller-en-ligne-on-inline-wheels"/><ref name="vegter-everthing-about-wheel-profile"/><ref name="welch-demystify-inline-disciplines"/> It helps skaters achieve two seemingly conflicting goals. The first goal is to maximize grip (or [[Friction#Static friction|static friction]]) during deep edging, allowing skaters to convert lateral [[#Striding and gliding|push-offs]] into forward motion over a longer stride. The second goal is to minimize rolling friction (or [[rolling resistance]]) when upright, enabling longer, faster [[#Striding and gliding|glides]] with less energy loss.<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/><ref name="publow-speed-skating-1999"/>{{rp|316}}

"Large" wheels act like [[flywheel]]s, storing [[rotational energy]] that helps skaters reach and maintain high speeds over long distances. Their [[Gyroscope|gyroscopic effect]] stabilizes direction, reducing energy loss from lateral drift. However, their greater mass makes them slower to [[Acceleration|accelerate]].<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/><ref name="powell-svensson-inline-skating"/>{{rp|24–25}} In contrast, "small" wheels have lower rotational inertia, allowing faster starts and quicker maneuvers. They also lower the center of gravity for better control, but give a bumpier ride and perform poorly over bumps, cracks, sticks, and pebbles.<ref name="skamidan-inline-skating-in-brief"/><ref name="vegter-everthing-about-wheel-diameter"/>

=== Wheel hardness and deformation ===

[[File:Footprint of an inline skate wheel showing a deformed profile from weight of a skater-FRD.svg|thumb|right|upright|Wheels deform under the weight of the skater]]

{{Main|Inline skate wheel#Hardness and deformation}}

[[#Polyurethane wheels|Polyurethane wheels]] [[Deformation (engineering)|deform]] [[Elasticity (physics)|elastically]] under a skater's weight, which increases ground contact and improves grip. This [[contact area]], known as the "footprint", differs slightly from an unloaded wheel's [[#Wheel diameter and profile|profile]].<ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/><ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/> The ideal deformation varies by surface. On slippery [[Roller rink|indoor rinks]] with polished wood floors, softer wheels are better because they deform more and enhance [[Friction#Static friction|traction]]. On rough outdoor [[Asphalt concrete|asphalt]], harder wheels are preferred since the surface already offers enough grip with minimal footprint.<ref name="naomi-grigg-2014"/>{{rp|18–19}}<ref name="skatepro-complete-guide-to-inline-wheels"/><ref name="bladeville-hardness-of-inline-skate-wheels">{{cite web
|url=https://bladeville.com/blog/hardness-of-inline-skate-wheels
|title=Choosing hardness of inline skating wheels
|website=Bladeville
|date=2013-09-17
|url-status=live
|archive-url=https://web.archive.org/web/20250418010559/https://bladeville.com/blog/hardness-of-inline-skate-wheels
|archive-date=2025-04-18
|access-date=2025-04-18
}}</ref> Balancing grip is essential. Too little grip causes slipping during [[#Striding and gliding|strides]], wasting energy. Too much grip creates rolling resistance, sapping speed during [[#Striding and gliding|glides]].<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/><ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/>

{{multiple image
 | direction = vertical
 | width = 90
 | image1 = Revision Flex Hockey Wheels-80mm-Firm-76A-IMG 6339-backlit-bg-FRD.png
 | caption1 = 76A indoor
 | image2 = Roces Impala 2023 Lightspeed Fairy Floss 70mm 84A inline skate wheel w bearings-IMG 6671-bg-FRD.png
 | caption2 = 84A outdoor
 | image3 = Powerslide Spinner 90mm 88A inline skate wheels with Wicked ABEC 9 bearings-IMG 5926-bg-FRD.png
 | caption3 = 88A urban
 | image4 = Razors Shift Pro Jeph Howard 2 60mm 90A aggressive wheel w bearings-IMG 6607-bg-FRD.png
 | caption4 = 90A aggro
}}

[[#Rolling resistance|Rolling resistance]] is generally higher with softer wheels because they deform more, while harder wheels require less effort to start rolling and maintain speed on smooth surfaces. However, "on [[Surface roughness|rough terrain]]", hard wheels can increase rolling resistance by wasting energy as they repeatedly [[Work (physics)|lift]] skater's weight over small bumps, thus offsetting their typical quick acceleration and higher sustained speed. Softer wheels, though slower due to deformation, absorb surface irregularities better and help minimize energy loss in addition to providing a smoother ride.<ref name="outside-online-tire-rolling-resistance-bikes">{{cite web
|url=https://velo.outsideonline.com/road/road-racing/causes-of-rolling-resistance-and-our-protocols-when-testing-it/
|title=Causes of tire rolling resistance, and our protocols when testing it
|date=2021-09-29
|website=Outside Online
|url-status=live
|archive-url=https://web.archive.org/web/20250421025254/https://velo.outsideonline.com/road/road-racing/causes-of-rolling-resistance-and-our-protocols-when-testing-it/
|archive-date=2025-04-21
|access-date=2025-04-21
}}</ref><ref name="hamilton-rolling-resistance-and-wheels"/><ref name="cross-surface-roughness-on-rolling-resistance"/>

Wheel deformation depends on the skater's weight, the wheel's hardness, and its temperature. While weight and hardness stay constant, temperature varies with [[Weather|ambient conditions]], surface heat, and [[Bearing (mechanical)#Friction|bearings friction]] from high-speed skating. As temperature rises, the polyurethane softens, causing the wheel to deform more and reducing its effective hardness.{{efn-ua|name=notes-on-brennan-olson-1987-lightning-patent}}<ref name="inline-warehouse-wheel-buying-guide">{{cite web
|url=https://www.inlinewarehouse.com/fitlc/wheels/inline-wheel-buying-guide.html
|title=Inline Skate Wheel Buying Guide
|website=Inline Warehouse
|date=June 2019
|url-status=live
|archive-url=https://web.archive.org/web/20250315024345/https://www.inlinewarehouse.com/fitlc/wheels/inline-wheel-buying-guide.html
|archive-date=2025-03-15
|access-date=2025-04-17
}}</ref><ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/>

"Wheel hardness" is measured on the [[Shore durometer|Shore A durometer scale]], which ranges from 0A (softest) to 100A (hardest). Inline skate wheels usually range from 72A to 95A. Indoor [[#Hockey|hockey]] wheels are softest at 72A to 78A. [[#Recreational|Recreational]] outdoor wheels are slightly harder, between 80A and 84A. Freestyle slalom and [[#Urban|urban]] wheels range from 83A to 88A, while [[#Aggressive|aggressive]] wheels are hardest at 88A to 95A.<ref name="joyner-inline-hockey-1995"/>{{rp|21–22}}<ref name="liveabout-carlesa-williams-wheels-101"/><ref name="bladeville-hardness-of-inline-skate-wheels"/><ref name="skatepro-complete-guide-to-inline-wheels"/>

Within the appropriate "hardness range" for an activity, softer wheels offer better grip for quicker acceleration during lateral strides, and a smoother ride on uneven surfaces, though they wear out faster. Harder wheels allow for higher gliding speeds, resist wear on rough surfaces, and offer a more responsive feel, but they can lead to a bumpier ride and some energy loss.<ref name="usenet-chen-FAQ-inline-origin"/><ref name="skatepro-complete-guide-to-inline-wheels"/>

=== Dual density wheels ===

{{Main|Inline skate wheel#Dual density}}

Dual density wheels were developed to address the long-standing challenge of choosing a single [[#Wheel hardness and deformation|wheel hardness]] to meet opposing needs. Softer wheels provided shock absorption over rough terrain and better grip at deep edging angles, while harder wheels offered greater wear resistance and higher speeds on smooth, upright glides. Skaters had to [[#Trade-offs|compromise]], as no single hardness met both demands effectively.<ref name="us-patent-6227622-k2-dual-density-pu-1997">{{Cite patent
|country=US
|number=6227622
|fdate=1997-06-20
|pubdate=2001-05-08
|gdate=2001-05-08
|title=Multilayer skate wheel
|inventor1-first=John A.
|inventor1-last=Roderick
|inventor2-first=Albert C.
|inventor2-last=Chiang
|inventor3-first=James A.
|inventor3-last=Vandergrift
|assign1=K2 Corp
|assign2=Fleet National Bank
}}</ref><ref name="le-roller-en-ligne-on-dual-density-wheels-2015">{{cite web
|url=https://www.rollerenligne.com/dossier/dual-density-skate-wheels-where-does-the-technology-comes-from-and-what-is-the-use-of-it/?lang=en
|title=Dual density skate wheels: Where does the technology comes from and what is the use of it?
|first1=Alexandre 'alfathor'
|last1=Chartier
|date=2015-01-18
|website=Le Roller en Ligne
|url-status=live
|archive-url=https://web.archive.org/web/20250419024148/https://www.rollerenligne.com/dossier/dual-density-skate-wheels-where-does-the-technology-comes-from-and-what-is-the-use-of-it/?lang=en
|archive-date=2025-04-19
|access-date=2025-04-19
}}</ref>

[[File:K2 Corp-US6227622B1-1997-Multilayer inline skate wheel-Patent Drawing-FIG 1A 1B-cropped.png|thumb|right|upright|Dual durometer wheel]]

{{multiple image
 | direction = horizontal
 | total_width = 260
 | image1 = Neal Piper-US7090306B1-2004-Inline skate wheel w soft tire n internal support-Patent Drawing-FIG 4A 4B 4C-rearranged.png
 | image2 = Revision Flex Hockey Wheels-80mm-Firm-back-76A-IMG 7141-bg-FRD.png
 | footer = Soft tire molded over harder support
}}

In 1997, [[K2 Sports|K2]] patented a "dual [[Shore durometer|durometer]]" wheel, later known as a "dual density" wheel, aimed at combining a ''smooth ride over rough terrain'' with the ''durability'' and ''speed'' of hard wheels. Unlike single-compound wheels, it used two [[polyurethane]] layers: a hard outer tire (70A to 100A) for wear resistance and speed, and a soft inner ring (20A to 75A) to absorb shocks and vibrations.<ref name="us-patent-6227622-k2-dual-density-pu-1997"/>

In 1997, Neal Piper and Tom Peterson of Hyper Wheels patented a similar dual-layer wheel concept, but used a triangular [[Reticulated foam|foam]] [[mandrel]] instead of a soft polyurethane ring. This design aimed to match the benefits of K2's dual-durometer wheels, while also improving ''grip during deep edging''. The foam mandrel's shape prevented [[#Wheel hardness and deformation|deformation]] at the wheel's tip during upright skating, while allowing the sides to flex under [[#Side load support|angled loads]], enhancing grip during [[#Striding and gliding|strides]] and turns at about a 30° tilt.<ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/>

In 2004, Neal Piper patented a multi-density wheel that reversed his 1997 design by using a soft outer polyurethane layer (60A to 75A) over a much harder internal support structure (80A to 95A or more). First seen in ''Variant'' hockey wheels from Revision, and later in the ''Recoil'' and ''Flex'' lines, this design gave [[Inline hockey|hockey]] players ''top speed'' without sacrificing ''high grip''.<ref name="us-patent-7090306-neal-piper-multi-density-pu-2004">{{Cite patent
|country=US
|number=7090306
|fdate=2004-06-04
|pubdate=2006-08-15
|gdate=2006-08-15
|title=Inline wheel with softer tire and internal support structure
|inventor1-first=Neal
|inventor1-last=Piper
}}</ref><ref name="revision-hockey-wheels-multi-density-flex-recoil-variant">{{cite web
|url=https://www.revisionhockey.com/wheels
|title=Reivision wheels: Flex, Recoil and Variant
|website=Revision Hockey
|url-status=live
|archive-url=https://web.archive.org/web/20250420035314/https://www.revisionhockey.com/wheels
|archive-date=2025-04-20
|access-date=2025-04-20
}}</ref><ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/>

=== Wheel rebound ===

{{Main|Inline skate wheel#Rebound}}

[[File:Playing inline hockey on a parking lot-IMG 9273-FRD.jpg|thumb|right|Rebound improves cornering]]

Wheel rebound is the [[energy]] a [[#Polyurethane wheels|polyurethane wheel]] returns as it recovers its shape after being [[#Wheel hardness and deformation|elastically deformed]]. Though widely discussed, there is no consensus on how to rate it.<ref name="powell-svensson-inline-skating"/>{{rp|24–26}} Unlike other wheel traits that depend on skating style or terrain, rebound is universally desired. Higher rebound is always preferred, if cost were not a factor.<ref name="bladeville-hardness-of-inline-skate-wheels"/>

[[File:Foco Roberta in azione durante una run di Skate Slalom.jpg|thumb|right|High rebound wheels feel lively and responsive]]

"High-rebound" wheels feel lively and responsive, helping skaters roll faster with less effort by [[Energy transformation|converting]] more energy from each push into forward motion.<ref name="gallaghercorp-polyurethane-resilience-elasticity-rebound"/> "Low-rebound" wheels feel dead, [[Dissipation|absorbing energy]] like flat tires and requiring more effort to maintain speed, similar to walking on soft sand.<ref name="inline-warehouse-wheel-buying-guide"/>

A [[Polyurethane|polyurethane compound]] can be formulated with varying rebound levels regardless of hardness. "Hardness" affects how much a wheel [[Deformation (engineering)|compresses]] under load, while "rebound" measures how much of that energy is [[Energy conversion efficiency|converted]] to aid forward motion. These are separate, distinct properties.{{efn-ua|name=gallaghercorp-rebound-is-not-hardness}}

Rebound can be measured using tests like the [[Bayshore Resilience]] test, which compares rebound height to drop height, and the Rebound Resilience test, which measures percentage of energy return. These tests assess "polyurethane resilience", another term for rebound, but their quantification of [[Elasticity (physics)|elasticity]] are not directly comparable. Inline skate wheels rarely list rebound in technical datasheets, and when they do, it's usually under vague labels like High Rebound (HR) or Ultra High Rebound (UHR).<ref>{{cite web
|url=https://elastomer-institut.de/en/pruefungen/rebound-resilience/
|title=Rebound Resilience
|website=Elastomer Institut, part of OPR Group GmbH
|url-status=live
|archive-url=https://web.archive.org/web/20250423033418/https://elastomer-institut.de/en/pruefungen/rebound-resilience/
|archive-date=2025-04-23
|access-date=2025-04-23
}}</ref><ref name="usenet-chen-FAQ-inline-wheels"/><ref name="powerslide-download-guides-wheels"/>

In [[mechanics]], rebound is closely linked to [[Hysteresis#Elastic hysteresis|elastic hysteresis]], its complementary property, which measures energy lost as heat during deformation and recovery. The two are [[Proportionality (mathematics)#Inverse proportionality|inversely proportional]]: higher hysteresis means more energy loss and lower rebound.<ref name="gallaghercorp-hysteresis-in-urethane">{{cite web
|url=https://gallaghercorp.com/hysteresis-in-urethane/
|title=Hysteresis in Urethane
|website=Gallagher Corporation
|url-status=live
|archive-url=https://web.archive.org/web/20250425024211/https://gallaghercorp.com/hysteresis-in-urethane/
|archive-date=2025-04-25
|access-date=2025-04-25
}}</ref>

=== Rolling resistance ===

{{Main|Inline skate wheel#Rolling resistance}}

[[File:Roller speed skating at the 2018 Summer Youth Olympics – Boys Quarterfinals Run 4 66-zommed in.jpg|thumb|right|Minimizing rolling resistance]]

{{multiple image
 | total_width = 230
 | direction = horizontal
 | image1 = Skate - Flickr - digicla.jpg
 | image2 = StylePassi.jpg
 | footer = Surfaces: rough vs. smooth
}}

[[Rolling resistance]] (also rolling friction or drag) is a key factor limiting a skater's top speed. It opposes wheel motion and is mainly caused by [[elastic hysteresis]].<ref name="publow-speed-skating-1999"/>{{rp|316}}<ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/> To reduce it, manufacturers design polyurethane compounds for [[#Wheel rebound|high rebound]] and thus low hysteresis, which is especially important in [[Inline speed skating|speed skating]].<ref name="outside-online-tire-rolling-resistance-bikes"/><ref name="naomi-grigg-2014"/>{{rp|18–19}}

Skater weight and wheel hardness affect [[#Wheel hardness and deformation|wheel deformation and footprint size]], which influences rolling resistance. Speed skaters prefer hard, [[#Wheel diameter and profile|pointy-profile]] wheels to keep footprints small and reduce resistance, while gliding upright. [[#Dual density wheels|Dual-density]] wheels were developed to minimize footprint while preserving comfort.<ref name="publow-speed-skating-1999"/>{{rp|316}}<ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/>

[[Surface roughness|Terrain roughness]] also affects rolling resistance, as energy is wasted repeatedly [[Work (physics)|lifting]] the skater over small surface imperfection. The need to cushion bumpy rides ''without'' increasing the footprint was another driving force behind dual-density wheels.<ref name="hamilton-rolling-resistance-and-wheels"/><ref name="us-patent-6227622-k2-dual-density-pu-1997"/><ref name="cross-surface-roughness-on-rolling-resistance"/>

[[#Wheel diameter and profile|Wheel diameter]] plays another key role in rolling resistance, ''especially'' on rough terrain. Larger wheels reduce resistance by smoothing out surface imperfections and lowering the angle of contact with small bumps. This reduces [[Dissipation|energy loss]]. As a result, wheels between {{nowrap|90 mm}} and {{nowrap|125 mm}} are common in [[#Urban|urban]] and [[#Speed|marathon]] skates, where both speed and handling uneven surfaces are important.<ref name="cross-surface-roughness-on-rolling-resistance">{{cite journal
| last1 = Cross
| first1 = Rod
| year = 2015
| title = Effects of surface roughness on rolling friction
| url = https://www.researchgate.net/publication/281666081
| access-date  = 2025-04-26
| url-status=live
| archive-url  = https://web.archive.org/web/20250427002637/https://www.researchgate.net/publication/281666081_Effects_of_surface_roughness_on_rolling_friction
| archive-date = 2025-04-27
| journal = [[European Journal of Physics]]
| volume = 36
| number = 6
| doi = 10.1088/0143-0807/36/6/065029
| bibcode = 2015EJPh...36f5029C
}}</ref><ref name="hamilton-rolling-resistance-and-wheels"/><ref name="welch-demystify-inline-disciplines"/>
{{Clear}}

== Bearings ==

[[File:Anatomy of Frame Wheel n Axle Assemblies in Inline Skates with labels n transfixed parts.svg|thumb|right|upright=0.6|Function]]

[[File:Rolling-element bearing (numbered).png|thumb|right|upright=0.6|Grooves & balls]]

{{Main|Inline skate bearing}}

[[Ball bearing]]s allow inline skate wheels to spin freely by separating the moving wheels from the non-moving structure.<ref name="usenet-chen-FAQ-inline-bearings"/> [[#Wheels|Wheels]] rotate around [[axle]]s that are tightly bolted to the [[#Frames|frame]], which is securely attached to the [[#Boots|boot]] using fasteners. Bearings minimize [[friction]] between the wheel and axle, enabling greater speed with less effort.<ref name="powell-svensson-inline-skating"/>{{rp|26–29,39–45}}{{efn-ua|name=xinhaidude-bearing-spacers-preloading|
Consult sections on bearings, spacers, wheel assembly, and bearing preloading from the Big Wheel article.<ref name="xinhaidude-ps-trinity-reign-as-big-wheel-urban-skate"/>
}} The adoption of modern [[International Organization for Standardization|ISO]] 608 ball bearings, combined with [[polyurethane]] wheels, helped propel inline skating to [[History of inline skates#Modern inline skates|its peak popularity]] in the 1990s.<ref name="bernstein-minnesota-hockey-inline"/><ref name="vegter-names-in-inline-skating"/>

An ISO 608 ball bearing has two concentric rings: an [[Race (bearing)|outer race]] attached to the rotating [[#Wheel hubs|wheel hub]] and an [[Race (bearing)|inner race]] fixed to the stationary axle. Between them are 5 to 8 [[Ball (bearing)|rolling balls]]. [[Ball bearing#Deep-groove|Deep grooves]] in the races form raceways that hold the balls securely. A retainer, or cage, keeps the balls evenly spaced along the raceways.<ref name="powerslide-download-guides-bearings-by-wicked"/><ref name="powell-svensson-inline-skating"/>{{rp|26–29,39–45}}{{efn-ua|name=xinhaidude-bearing-spacers-preloading}}<ref name="skf-group-rolling-bearings-1152-pages-2018"/>

=== Purpose-built bearings ===

{{Main|Inline skate bearing#Purpose-built}}

The [[ABEC scale]] rates bearing [[Engineering tolerance|precision]] from 1 to 9 (highest) in odd numbers, originally for high-speed industrial machinery. Higher ABEC ratings show better precision (or tolerance) but are only one of many factors in a bearing's suitability for [[inline skating]].<ref name="powell-svensson-inline-skating"/>{{rp|27–28}}<ref name="usenet-chen-FAQ-abec-hype"/> For inline skating, any ABEC-rated bearing is sufficient, considering that an average skater cruising on {{nowrap|80 mm}} wheels reaches only about 1,326 RPM. This is just 3.5% of the mechanical [[Bearing (mechanical)#Speeds|limiting speed]] (38,000 RPM) of ABEC 3-rated 608 bearings from [[SKF]].{{efn-ua|name=skf-608-bearing-abec-3-limiting-speed|
SKF’s 1,152-page rolling bearings catalog lists a limiting speed of 38,000 RPM for its Explorer-class 608-2Z bearings (pages 135 and 262). These bearings meet ISO 492 Class 6 precision tolerances, which are equivalent to ABEC 3, as noted on pages 7, 36, 248, and 250.<ref name="skf-group-rolling-bearings-1152-pages-2018"/>
}}<ref name="get-rolling-blog-engineer-perspective-on-skating"/>

[[File:Inline bearings-TRUE Swiss-Bones REDS-alike-Non-contact shield removed-IMG 7484-2-FRD.jpg|thumb|right|upright=0.8|Bones Swiss]]

However, ABEC does not account for [[Materials science|material]] type, [[List of materials properties|quality]], [[durability]], or how bearings handle [[dirt]], [[moisture]], and other factors crucial for skating performance. Recognizing the unique demands of skating, George Powell worked with a [[Switzerland|Swiss]] manufacturer to develop 608 bearings specifically for [[skateboarding]], launching Bones Swiss in 1983. Unlike standard bearings made for [[electric motor]]s operating in [[Cleanroom|clean environments]], Bones Swiss bearings were purpose-built and designed to withstand [[#Side load support|multi-directional abuses]] from street skating.<ref name="bones-bearings-history-by-george-powell"/><ref name="bones-bearings-maintaining-your-bones-bearings"/> They featured a serviceable outer [[Seal (mechanical)|shield]] for easy access when cleaning. The inner side was left open, and [[Injection moulding|molded]] plastic [[Ball bearing#Construction types|retainers]] could be temporarily removed when accessing and cleaning the [[Ball (bearing)|balls]] and [[Race (bearing)|raceways]]. Powell also created a custom [[lubricant]] suited to skating conditions.<ref name="vandem-longboard-on-skateboard-bearings-the-truth"/><ref name="usenet-chen-FAQ-inline-bearings"/><ref name="inmoveskates-roller-skate-bearings"/>

Reputable skate bearing brands typically avoid ABEC ratings, as they don't reflect design features specific to skating. Instead, bearings are marketed under specialized product lines. [[Powell Peralta#Bones Bearings|Bones Bearings]], for instance, offers Bones Swiss, Bones Swiss Ceramic, Bones REDS®, and Bones Big Balls®, all labeled Skate Rated™ to show they are [[Mechanical engineering|engineered]] for real skating demands. Powell's “Swiss” design and engineering has become an [[Benchmarking|industry benchmark]] in both skateboarding and inline skating, though some imitation brands sell “Swiss” bearings that mimic the structure and claims without being made in Switzerland.<ref name="publow-speed-skating-1999"/>{{rp|317–318}}<ref name="naomi-grigg-2014"/>{{rp|22–24}}<ref name="bones-bearings-skate-rated-system"/><ref>{{cite web
|url=https://www.devaskation.com/what-are-swiss-bearings/
|title=What are Swiss Bearings?
|website=Devaskation
|date=22 September 2020
|url-status=live
|archive-url=https://web.archive.org/web/20250418171329/https://www.devaskation.com/what-are-swiss-bearings/
|archive-date=2025-04-18
|access-date=2025-05-17
}}</ref>

[[File:Inline bearings-Max ILQ-like Abec 3-Disassembled-IMG 7556-FRD.jpg|thumb|right|upright=0.8|OEM TWINCAM ILQ-7]]

Similarly, TWINCAM bearings were created in the early 1990s specifically for inline skating, marketed with the slogan “Beyond ABEC”. In 1991, they introduced serviceable bearings with removable shields held in place with a [[Circlip|C-clip]], followed in 1992 by TK CLASSIC Racing Gel, a [[water-repellent]] lubricant. In 2002, they launched the ILQ-9, a 6-ball bearing, as an alternative to the standard 7-ball setup. The ILQ line later expanded to include models such as ILQ-9 Pro with rubber shields, ILQ-7 for [[Original equipment manufacturer|OEM]] skates, ILQ-X mr2 with reduced weight, and ILQ-Midget with 11 balls. TWINCAM trademarked "ILQ" (InLine Qualified) as a proprietary rating system, and had various ILQ models rebranded and redistributed by partners such as FR Skates, [[K2 Sports|K2]], [[Rollerblade]], and Powerslide/Wicked.<ref name="twincam-ilq-asia-access-history">{{cite web
|url=http://www.twincambearing.com/
|title=TWINCAM home page
|website=TWINCAM Bearing
|url-status=dead
|archive-url=https://web.archive.org/web/20130305191532/http://www.twincambearing.com/
|archive-date=2013-03-05
|access-date=2025-05-16
}}</ref><ref name="loco-skates-on-twincam-ilq-bearings">{{cite web
|url=https://www.locoskates.com/blogs/help-articles/what-does-twincam-and-ilq-bearings-mean
|title=What are Twincam and ILQ Bearings?
|date=2025-02-13
|website=Loco Skates
|url-status=live
|archive-url=https://web.archive.org/web/20250512020518/https://www.locoskates.com/blogs/help-articles/what-does-twincam-and-ilq-bearings-mean
|archive-date=2025-05-12
|access-date=2025-05-16
}}</ref><ref name="skatepro-all-aspects-of-speed-skates"/>

=== Contamination and bearing friction ===

{{Main|Inline skate bearing#Contamination and friction}}

Skaters lose energy not only from [[#Rolling resistance|wheel rolling resistance]] but also from bearing [[friction]], caused by internal components like balls, cage, lubricant, and seals.<ref name="hambini-ceramic-vs-steel-bearings-friction-analysis"/><ref name="pib-factors-affecting-bearing-friction"/> However, in clean, [[Lubrication|well-lubricated]] bearings, this friction is minimal compared to rolling resistance of polyurethane wheels. Most [[#Purpose-built bearings|purpose-built bearings]] from reputable brands meet or exceed ABEC 3 specs, so bearing selection has little effect on performance when bearings are new.<ref name="hamilton-rolling-resistance-and-wheels"/><ref name="get-rolling-blog-engineer-perspective-on-skating"/><ref name="publow-speed-skating-1999"/>{{rp|317–318}}<ref name="naomi-grigg-2014"/>{{rp|22–24}}

[[File:Inline bearings-Bauer ZZ metal gap shield-Non removable-Disassembled-IMG 7668-FRD.jpg|thumb|right|Dirt trapped inside a bearing]]

Bearing selection plays a significant role over the [[Product lifetime|lifetime]] of bearings, however, because performance depends on how well bearings resist contamination from [[dirt]], [[dust]], and [[moisture]]. Even [[Microscopic scale|microscopic particles]] can damage [[Race (bearing)|raceways]] and hinder smooth rotation. ''Contamination'' is the most harmful factor; it reduces [[Energy conversion efficiency|efficiency]] or causes bearings to seize.<ref name="miniature-bearings-australia-skate-bearing-faq"/><ref name="bones-bearings-maintaining-your-bones-bearings"/> As skaters say, the fastest bearings in the world are simply ones that are new or freshly cleaned and lubricated.<ref name="vandem-longboard-on-skateboard-bearings-the-truth"/><ref name="usenet-chen-FAQ-abec-hype"/>

=== Bearing shields ===

{{Main|Inline skate bearing#Shields}}

{{multiple image
 | direction = horizontal
 | total_width = 220
 | image1 = Inline bearings-Bauer ZZ metal gap shield-Gap illustrated-IMG 7649-FRD.jpg
 | image2 = Inline bearings-Bauer ZZ metal gap shield-Gap illustrated-IMG 7644-FRD.jpg
 | footer = Z shields showing gaps
 }}

[[#Purpose-built bearings|Inline skate bearings]] are protected from [[contamination]] using four main [[Seal (mechanical)|shield]] types: (Z) non-serviceable metal gap shields, (ZS) serviceable metal gap shields with a C-ring, (RS) serviceable rubber gap shields bonded to a metal insert, and (RSL) full-contact labyrinth rubber lip seals.<ref name="usenet-chen-FAQ-inline-bearings"/>{{efn-ua|name=bearing-sealing-designations|
Bearing shielding and sealing are designated by suffixes that vary between manufacturers. These designations are typically published in technical handbooks and catalogs.<ref name="bds-bearings-complete-guide-bearing-seals-types-designations"/> One NTN suffix conversion table can be found on page 178 of the Bearing Nomenclature Guide by BDS.<ref name="bds-bearings-bearing-nomenclature-guide"/> There is no industry-wide standard that clearly defines when a "shield" becomes a "seal", nor where non-contact shields end and light-contact or non-contact seals begin. Likewise, the skating industry adopts suffixes inspired by those used in the bearing industry, but does not apply them consistently across brands.<ref name="usenet-chen-FAQ-inline-bearings"/> Generally, removable metal gap shields are labeled with the suffix "Z" in a fairly uniform way. See [https://bladeville.com/rollerblade-training-sg-9.html Rollerblade SG9 bearings] ([https://web.archive.org/web/20240814200225/https://bladeville.com/rollerblade-training-sg-9.html archived]). C-ring mounted metal gap shields, popularized by TWINCAM, are rarely marked with a distinct suffix, but when they are, they follow the "ZS" convention used by SKF.<ref name="powerslide-download-guides-bearings-by-wicked"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/> The skating industry’s use of the "RS" suffix typically refers to a non-contact NBR shield that physically resembles the RS/2RS contact lip seals used by INA/Schaeffler, but instead leaves a narrow gap, similar to SKF’s non-contact "RZ" shields.<ref name="miniature-bearings-australia-skate-bearing-faq"/><ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/><ref name="schaeffler-ina-product-reference-guide-2003"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/> The "RSL" suffix in skating refers to a full-contact labyrinth seal, comparable to SKF’s own RSL low-friction seals, except that SKF RSL leaves small gaps while bending the contamination path.<ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>}}<ref name="joyner-inline-hockey-1995"/>{{rp|42–45}}

'''Z shields''': simple metal covers that snap into the outer [[Race (bearing)|race]] without touching the inner race, leaving a small non-contact gap. They create no [[Friction|drag]] but offer limited protection and cannot be removed without damage. Bearings with shields on both sides are labeled "ZZ" and are non-serviceable (e.g., Rollerblade SG).<ref name="vandem-longboard-on-skateboard-bearings-the-truth"/><ref name="ntn-snr-rolling-bearings-handbook-2017"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>{{efn-ua|name=bearing-sealing-designations}}

{{multiple image
 | direction = horizontal
 | total_width = 220
 | image1 = Inline bearings-Max ILQ-like Abec 3-C ring removed-IMG 7536-FRD.jpg
 | image2 = Inline bearings-Max ILQ-like Abec 3-Non-removable metal retainer n balls-IMG 7548-FRD.jpg
 | footer = ZS shields released by C-ring
 }}

'''ZS shields''': similar to Z shields, but feature a removable [[Circlip|C-clip]] (C-ring), allowing for easy shield removal for maintenance. They are similarly non-contact and low-drag, and similarly provide minimal defense against dirt and moisture. Their main advantage is serviceability: that skaters can remove and reattach the shields without damage, enabling regular cleaning and [[Lubrication|relubrication]]. This design is used in [[#Purpose-built bearings|TWINCAM ILQ]]-style bearings, with double-shielded ones often labeled "2ZS" or "ZZS".<ref name="powerslide-download-guides-bearings-by-wicked"/><ref name="usenet-chen-FAQ-inline-bearings"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>{{efn-ua|name=bearing-sealing-designations}}

[[File:Inline bearings-TRUE Swiss-Bones REDS-alike-Disassembled-Exploded view-IMG 7518-7520-7526-7528-7533-bg-FRD.png|thumb|right|upright=1.1|RS shield in Bones Swiss]]

'''RS shields''': use a [[nitrile rubber]] shield bonded to a metal insert. In skating, RS rubber shields specifically refer to the design popularized by [[#Purpose-built bearings|Bones Swiss]]. They offer better protection than Z or ZS shields and are removable for cleaning and maintenance. Many skate brands use only one RS shield, leaving the inner side open and protected by the [[#Wheel hubs|wheel hub]], allowing easy lubrication access without even removing the shield.<ref name="miniature-bearings-australia-skate-bearing-faq"/><ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/><ref name="schaeffler-ina-product-reference-guide-2003"/><ref name="skf-group-rolling-bearings-1152-pages-2018"/>{{efn-ua|name=bearing-sealing-designations}}

[[File:Kugellager.jpg|thumb|right|upright=0.5|Heavy grease]]

'''RSL seals''': full-contact rubber seals with a [[Labyrinth seal|labyrinth]] lip profile that lightly touches the inner race, blocking dirt and moisture. These are used with "thick grease" for long-lasting protection with "near-zero maintenance", but cause more "bearing drag".<ref name="skf-group-rolling-bearings-1152-pages-2018"/>{{efn-ua|name=bearing-sealing-designations}} Though they don't spin freely when unloaded, they perform efficiently under a skater's weight, when grease is forced away from ball paths as wheels roll. Dragon Bearings produces "2RSL" models with RSL seals on both sides.<ref name="hambini-ceramic-vs-steel-bearings-friction-analysis"/><ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/>
{{Clear}}

== Skate tuning ==

{{Main|Inline skate tuning}}

{{multiple image
 | direction = horizontal
 | width1 = 120
 | width2 = 150
 | image1 = Razors Shift Jeph Howard 2-Profile-IMG 6111-bg-FRD.png
 | image2 = Powerslide Reign Ares hybrid skates-on Endless 90 Trinity frame and 110mm wheels-ortho side view-IMG 4978-bg-FRD.png
 | footer = Standard aggro vs. big-wheel urban setup
}}

Skate setup, customization and tuning terms vary by discipline. For instance, [[#Urban|urban skaters]] refers to four larger wheels (e.g. 4x90mm) and triskates with three large wheels ({{nowrap|110 mm}} or more) as "big-wheel setups". In contrast, [[#Aggressive|aggressive skaters]] consider anything {{nowrap|80 mm}} or larger to be big-wheel.<ref name="inmoveskates-big-wheels">{{cite web
|url=https://www.inmoveskates.com/learning-center/about-wheels/big-wheels-inline-skates-expirience
|title=Big wheels inline skates experience
|date=2022-07-12
|first1=Steven
|last1=Sanchez
|website=InMove Skates
|url-status=live
|archive-url=https://web.archive.org/web/20241105074627/https://www.inmoveskates.com/learning-center/about-wheels/big-wheels-inline-skates-expirience
|archive-date=2024-11-05
|access-date=2025-05-04
}}</ref><ref name="ricardo-lino-on-triskates-2016">{{cite AV media
|url=https://www.youtube.com/watch?v=hB44yOWbVmY
|first1=Ricardo
|last1=Lino
|title=Why Triskates? The Latest Generation Inline Skate
|date=2016-12-13
|via=YouTube
|language=en
|format=video
}} See video transcript.
</ref> On the other hand, large wheels are standard for [[#Speed|marathon skaters]], and a triskate under {{nowrap|125 mm}} is seen as small and unusual. Terms like "big-wheel" and "triskate" also imply specific [[#Frames|frame]] and [[#Boots|boot]] designs, as setups with {{nowrap|125 mm}} wheels need stronger frames and more supportive boots to handle increased speed and leverage.<ref name="inline-warehouse-choose-urban-skates"/><ref name="skatepro-all-aspects-of-speed-skates"/><ref name="ricardo-lino-on-triskates-2016"/>

{{multiple image
 | direction = horizontal
 | width1 = 120
 | width2 = 150
 | image1 = Inline skate parts-Boot n Frame-One wheel removed-PS Tau urban boot-Nexus Rocker 235mm frame-PS Spinner 90mm wheels-Right skate-IMG 3786-IMG -5879-FRD.png
 | image2 = Trinity mount-side view-PS Tau boot-Endless 90 Trinity frame-3x110mm wheels-IMG 3983-bg-FRD.png
 | footer = Same boot on different frames and wheels
}}

A [[#Wheel setup|wheel setup]] generally refers to both the number and size of wheels. Common examples include 4x80mm for [[#Recreational|recreational use]], and 3x110mm, popular with urban skaters in the 2020s. Older 5x80mm setups, once used in [[#Speed|speed skating]], are now mainly seen in wizard skating.<ref name="welch-demystify-inline-disciplines"/><ref name="bladeville-wizard-frames-and-rest"/> Wheel setups also involve "wheel arrangement", which affects performance. A [[#Flat setup|flat setup]] has all wheels touching the ground. A [[#Rockered setup|rockered setup]] raises the front and rear wheels for a curved profile. A [[#Hi-lo setup|hi-lo setup]] uses decreasing wheel sizes frontward (e.g. {{nowrap|80-78-76-74 mm}})), keeping all wheels grounded but raising the heel for a forward-leaning stance.<ref name="markus-thierstein-wheel-rockering"/><ref name="rerolling-inline-boot-frame-wheel-setups"/>

Skaters can customize one boot with different wheel setups for various purposes. A [[#Frame dimensions|short frame]] with {{nowrap|80 mm}} [[#Wheel hardness and deformation|soft wheels]] suits indoor use, while a longer frame with larger and harder {{nowrap|110 mm}} wheels works better for outdoor distance skating. Some frames, like the Endless 90, support both 4x90mm and 3x110mm setups. Even without changing the frame or boot, switching wheels with different hardness, rebound, diameter, or profile can significantly [[#Wheels|alter the skating experience]].<ref name="inline-warehouse-frame-buying-guide"/><ref name="endlessblading-86-frame-spec-comparison"/>

[[File:Inline skate parts-Frame-Nexus Rockerable 235mm frame-PS Spinner 90mm wheels-IMG 5890-FRD.png|thumb|right|Some components of a skate]]

An "axle assembly" includes the rods, screws, bolts, and bushings that secure a wheel to the frame. A "bearing assembly" has two [[#Bearings|ball bearings]] with a spacer and, when placed in a wheel hub with a tire, forms a "wheel assembly".<ref name="us-patent-6132006-skate-wheel-axle-assembly">{{Cite patent
|country=US
|number=6132006
|fdate=1998-07-15
|pubdate=2000-10-17
|gdate=2000-10-17
|title=In-line skate wheel axle assembly and frame
|inventor1-first=Peter G.
|inventor1-last=Post
}}</ref><ref name="us-patent-6309108-bearing-spacer-bearing-assembly"/><ref name="us-patent-app-20190247739-axle-bearing-wheel-assemblies">{{Cite patent
|country=US
|number=20190247739
|status=application
|fdate=2018-02-13
|pubdate=2019-08-15
|title=Single-wall inline skate frame and skate
|inventor1-first=John Erik
|inventor1-last=Svensson
|assign1=K2 Sports LLC
}}</ref> A "frame assembly" refers to all skate components except the boot and wheel assemblies. For recreational skates, this includes the frame, brake, boot-mounting hardware, and axle assemblies. In aggressive skates, it may also include H-blocks and parts for grinding.<ref name="us-patent-app-20190247739-axle-bearing-wheel-assemblies"/><ref name="us-patent-7931283-aggressive-frame-assembly">{{Cite patent
|country=US
|number=7931283
|fdate=2007-07-23
|pubdate=2009-01-29
|gdate=2011-04-26
|title=Frame assembly for in-line skate
|inventor1-first=Andreas C.
|inventor1-last=Wegener
|assign1=Sunshine Distribution Inc
}}</ref>

=== Wheel rotation ===

{{Main|Inline skate tuning#Wheel rotation}}

[[File:Wheel rotation-pattern 1 3 2 4-for 4 wheel setup-inline skates.svg|thumb|right|upright=0.55|{{nowrap|1-3/2-4}} rotation]]

[[File:Wheel rotation-pattern 4 1 2 3-for 4 wheel setup-inline skates.svg|thumb|right|upright=0.7|{{nowrap|4-1-2-3}} rotation]]

[[File:Wheel rotation-pattern Hi Lo-for 4 wheel setup-inline skates.svg|thumb|right|upright=0.7|Hi-lo rotation]]

Inline skate wheels wear down with use and need periodic "rotation" and eventual "replacement". Front wheels and [[#Edging and turning|inside edges]] wear faster, especially on the [[Handedness|dominant foot]], thus usually the right foot for right-handed skaters. Uneven wear can distort the [[#Wheel diameter and profile|wheel profile]], and severely worn wheels risk de-coring (disbonding from [[#Wheel hubs|wheel hub]]) during use.<ref name="powell-svensson-inline-skating"/>{{rp|45–50}}<ref name="inlineskates-wheel-rotation-and-maintenance">{{cite web
|url=https://www.inlineskates.com/Inline-Skate-Wheel-Rotation-and-Maintenance/article-5-7-2012,default,pg.html
|title=Inline Skate Wheel Rotation and Maintenance
|website=Inline Skates
|url-status=dead
|archive-url=https://web.archive.org/web/20211018235539/https://www.inlineskates.com/Inline-Skate-Wheel-Rotation-and-Maintenance/article-5-7-2012,default,pg.html
|archive-date=2021-10-18
|access-date=2021-10-18
}}</ref>

Regular wheel rotation helps distribute wear evenly, extending [[Product lifetime|lifespan]] of the entire set. This includes "repositioning" less-worn wheels to high-wear axles to balance diameter differences, "flipping" wheels to even out lopsided edge wear from motions such as [[#Striding and gliding|push-offs]], and "swapping" wheels between skates to address asymmetrical wear from foot dominance.<ref name="rollerblades-dryland-training-1985"/>{{rp|81–86}}<ref name="usenet-chen-FAQ-inline-wheels"/><ref name="markus-thierstein-wheel-rotation"/>

'''{{nowrap|1-3/2-4}} rotation''' is a common rotation pattern for four-wheel setups in the 21st century. It exchanges the first wheel with the third and the second with the fourth, repositioning them to balance diameter differences. Simultaneously, wheels are swapped between skates, flipping inside and outside edges to correct lopsided edge wear and foot dominance effects. Eventually, all wheels wear out and are replaced as a set.<ref name="powell-svensson-inline-skating"/>{{rp|45–50}}<ref name="miller-get-rolling-2003"/>{{rp|41–45}}

'''{{nowrap|4-1-2-3}} rotation''' is another common method, and it predates {{nowrap|1-3/2-4}}. This was first documented in the 1985 book ''Rollerblades: Dryland Training for Ice Hockey''. The front wheel moves to the fourth axle, while all others shift forward one position. The {{nowrap|4-1-2-3}} rotation lets each wheel pass through all axle positions, promoting even wear and enabling full set replacement when needed.<ref name="rollerblades-dryland-training-1985"/>{{rp|81–86}}<ref name="markus-thierstein-wheel-rotation"/><ref name="usenet-chen-FAQ-inline-wheels"/>

'''Hi-lo rotation''' eliminates abrupt changes in effective wheel diameters which occur with other rotation patterns when all wheels are fully-worn and replaced as a set. With this method, all eight wheels are removed, sorted by observed diameter, and stacked from largest to smallest. The two most worn may be discarded and replaced with new ones. Wheels are then remounted by increasing size, starting with the smallest on the front of the non-dominant skate, and ending with the largest on the rear of the dominant skate. This creates a [[#Hi-lo setup|hi-lo wheel setup]] that mimics [[#Forward flex|forward flex]] and maintains consistent ride height across rotations.<ref name="markus-thierstein-wheel-rotation"/>

=== Bearing alignment ===

[[File:Anatomy of Frame Wheel n Axle Assemblies in Inline Skates with labels n transfixed parts.svg|thumb|right|upright=0.7|Recess & abutment]]

[[File:Anatomy of a Wheel Assembly in Inline Skates showing Bearing Components with labels.svg|thumb|right|upright=0.65|Outer/inner races]]

[[File:Wheel assembly cross section-Bearings Spacer installed into hub with axle-Inline skates-Bearing planes-IMG 7783-IMG 7790-bg-annotated-FRD.png|thumb|right|upright=0.65|Bearing planes]]

{{Main|Inline skate tuning#Bearing alignment}}

Bearing ''misalignment'' is one of the most harmful issues in skating, second only to [[#Contamination and bearing friction|dirt contamination]] in bearings. When customizing or [[#Wheel rotation|replacing wheels]], bearings must be re-installed carefully. Misalignment can cause wheels to tilt, roll unevenly, drag against the frame, vibrate, and overheat. This reduces performance, risks tire debonding, and leads to premature wear of bearings and axles.<ref name="hirschmugl-august-skate-wheel-plastic-hub-patent-1954"/><ref name="peterverdone-bearings-and-lubrication">{{cite web
|url=https://www.peterverdone.com/archive/skatebearings.htm
|title=Bearings & Lubrication
|first1=Peter
|last1=Verdone
|date=2012
|website=PVD Designs
|url-status=live
|archive-url=https://web.archive.org/web/20120215062022/http://www.peterverdone.com/archive/skatebearings.htm
|archive-date=2012-02-15
|access-date=2025-05-31
}}</ref><ref name="powell-svensson-inline-skating"/>{{rp|39–45}}

In the 1980s, [[Rollerblade]] and [[Kryptonics (company)|Kryptonics]] developed [[#Wheel hubs|plastic hubs]] with precise, rigid "bearing seats" to align [[#Purpose-built bearings|bearings]] accurately. Each {{nowrap|7 mm}} deep "bearing recess" matches the width of an ISO 608 bearing, allowing flush mounting with [[Interference fit|press-fit]].<ref name="brennan-olson-1987-patent-modern-inline-skates"/><ref name="cryptonics-1995-patent-bearing-seat-to-eliminate-bearing-clicks"/><ref name="hook-1995-patent-two-piece-wheel-hubs"/> This leaves a {{nowrap|10 mm}} gap between two bearings mounted on a hub standardized at {{nowrap|24 mm}} wide. This gap is filled by a "bearing abutment" molded into the hub to position and support the bearings.<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/>

A ball bearing has two concentric [[Race (bearing)|races]] that rotate relative to each other. The outer race is secured to the hub and ''rotates'' with the [[#Polyurethane wheels|wheel]], while the inner race stays ''stationary'' with the axle assembly.<ref name="cryptonics-1995-patent-bearing-seat-to-eliminate-bearing-clicks"/> A "spacer" matching the {{nowrap|10 mm}} bearing abutment fits between the inner races. Tightening the axle bolt [[#Bearing preload|clamps]] the frame around the bearing assembly, creating a rigid structure that binds the axle, spacer, and inner races, securing them to the [[#Frames|frame]] and [[#Boots|boot]].<ref name="brennan-olson-1987-patent-modern-inline-skates"/><ref name="joyner-inline-hockey-1995"/>{{rp|19–24}}<ref name="miller-get-rolling-2003"/>{{rp|43–44}}

The bearing abutment and outer race of each bearing together define a "bearing plane". Both [[Euclidean plane|planes]] should be [[Parallel (geometry)|parallel]] and exactly {{nowrap|10 mm}} apart, with the spacer and inner races meeting at these same planes. Proper "bearing alignment" means all these [[Euclidean geometry|geometric relationships]] are correctly maintained.<ref name="brennan-olson-1987-patent-modern-inline-skates"/><ref name="cryptonics-1995-patent-bearing-seat-to-eliminate-bearing-clicks"/>

=== Side load support ===

{{Main|Inline skate tuning#Side load support}}

[[File:Radial load on Deep Groove Ball Bearings on Inline skates - labeled.svg|thumb|right|upright=0.9|Vertical load & radial play]]

[[File:Axial load on Deep Groove Ball Bearings on Inline skates - labeled.svg|thumb|right|upright=0.9|Side load and axial play]]

ISO 608 bearings in inline skates are [[Ball bearing#Deep-groove|deep groove ball bearings]] (radial ball bearings), designed primarily to handle [[Radius|radial]] [[Mechanical load|loads]] - forces applied [[perpendicular]] to the [[axle]] from the skater's weight. These loads pass from the [[#Boots|boot]] through the [[#Frames|frame]] and axles to the [[Race (bearing)|inner races]] and balls, pressing against the outer races. Radial load in skating is thus colloquially known as "[[Vertical direction|vertical]] load".<ref name="gmn-bearing-usa-on-radial-ball-bearings"/><ref name="smb-bearings-on-skate-bearings"/><ref name="bones-bearings-history-by-george-powell"/>

Radial ball bearings are also capable of handling a certain amount of [[Axis of rotation|axial]] load from both directions. These are side forces along the axle produced by maneuvers that involve a [[#Edging and turning|deep edge]], such as turning, [[Crossover (figure skating)|crossovers]], [[Powerslide (inline skating)|power slides]], power stops, and techniques like slalom or the [[double push]]. Axial load in skating is colloquially known as "side load".<ref name="jtekt-on-bearings-types-axial-and-radial-loads"/><ref name="smb-bearings-on-skate-bearings"/><ref name="bones-bearings-skate-rated-system"/>

Some [[#Purpose-built bearings|purpose-built bearings]], such as the Bones Swiss, are designed with larger internal [[Engineering fit|clearance]] (gaps between the balls and raceways) to better accommodate side loading.<ref name="bones-bearings-history-by-george-powell"/><ref name="bones-bearings-skate-rated-system"/><ref name="smb-bearings-on-skate-bearings"/> This enables increased "axial play" (or axial clearance), an intentional design and not a sign of lower [[Engineering tolerance|precision]]. It allows the inner race to shift laterally relative to the outer race, changing the [[Ball bearing#Angular contact|contact angle]] between balls and raceways to better support axial loads without binding.<ref name="smb-bearings-on-bearing-internal-clearance"/><ref name="nhbb-inc-on-internal-geometry-ball-bearings"/><ref name="ntn-snr-rolling-bearings-handbook-2017"/>

=== Bearing preload ===

{{Main|Inline skate tuning#Bearing preload}}

[[File:Radial Clearance without Preload in a Deep Groove Ball Bearing creating Non-load-bearing Zone - labeled.svg|thumb|right|upright=1.3|Radial play results in uneven load]]

[[File:Preload removes Clearance and Non-load-bearing Zone in a Deep Groove Ball Bearing - labeled.svg|thumb|right|upright=1.3|Preload ensures even load distribution]]

Greater internal [[Engineering fit|clearance]] in skate bearings helps [[#Side load support|prevent binding during side-loading]] maneuvers. However, it creates an uneven [[Stress–strain analysis|load distribution]], with only the bottom ball and its neighbors supporting the skater's weight. These form the "load-bearing zone", while the other balls remain unloaded.<ref name="jtekt-on-bearing-selection-05-bearing-preload-n-rigidity"/> As balls rotate through the bearing, they briefly enter the load-bearing zone and endure [[Stress (mechanics)|stress]] beyond their [[Strength of materials|design limits]], accelerating wear.<ref name="nasa-tech-report-on-internal-clearance-and-bearing-life-radial-ball-berings"/> At the top of rotation, balls lose contact due to clearance gaps, causing skidding, noise, energy loss, and more wear.<ref name="skf-group-on-bearing-damage-and-failure-analysis"/> Uneven surfaces add shifting forces that, combined with the clearance, cause axle vibrations and worsen [[#Bearing alignment|bearing misalignment]].<ref name="ntn-snr-rolling-bearings-handbook-2017"/><ref name="jtekt-on-bearing-selection-05-bearing-preload-n-rigidity"/><ref name="axis-baart-group-on-misalignment-capacity-of-deep-groove-ball-bearings"/>

[[Preload (engineering)#Bearing preload|Bearing preload]] in inline skates refers to a specific type of [[#Side load support|axial load]] - that from clamping the inner race against a [[#Spacer length|properly sized spacer]] using the axle bolt, [[Tension (physics)|pre-tensioning]] the bearing balls at an [[Ball bearing#Angular contact|oblique contact angle]]. This reduces or removes internal clearance, keeping all balls engaged and evenly distributing the skater's weight during wheel rotation.<ref name="smb-bearings-on-bearing-internal-clearance"/><ref name="jtekt-on-bearing-selection-05-bearing-preload-n-rigidity"/>

=== Spacer length ===

{{Main|Inline skate tuning#Spacer length}}

[[File:Bearing Spacer Proper Length - inline skate wheel assembly - with labels.svg|thumb|right|upright=0.9|Optimal spacer length]]

[[#Bearing preload|Preloading]] is especially useful in [[Inline speed skating|high-speed skating]], like downhill racing, where it removes [[Engineering fit|clearance gaps]], reduces skidding, and minimizes axle displacement. This improves wheel assembly's [[structural rigidity]], and increases skater's stability, precision and control.<ref name="smb-bearings-on-bearing-internal-clearance"/><ref name="skf-group-bearing-preload-2021"/> By using a correctly sized spacer, the axle bolt can apply just enough tension to create a slight negative internal clearance (around {{nowrap|-0.01 mm}}), the "optimal preload".<ref name="powerslide-on-inline-skate-spacers-and-proper-spacer-length"/><ref name="xinhaidude-ps-trinity-reign-as-big-wheel-urban-skate"/> This delivers optimal [[Stress–strain analysis|load distribution]] and load-carrying capacity, minimizing wear and maximizing bearing lifespan.<ref name="skf-group-bearing-preload-2021"/><ref name="nasa-tech-report-on-internal-clearance-and-bearing-life-radial-ball-berings"/><ref name="jtekt-on-bearing-selection-04-bearing-fits-n-internal-clearance"/>

[[File:Bearing Spacer Too Short - Axle Tight - inline skate wheel assembly - with labels.svg|thumb|right|upright=0.9|Short spacer binds wheels]]

'''Short spacer''': [[Engineering tolerance|Manufacturing imperfections]] often prevent spacers from [[#Bearing alignment|perfectly matching]] the bearing abutment length.{{efn-ua|name=ricardo-lino-with-tony-gabriel-tour-wheel-factory-notes}}<ref name="cryptonics-1995-patent-bearing-seat-to-eliminate-bearing-clicks"/><ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/> If a spacer is too short, overtightening the axle bolt beyond the optimal preload tension can create excessive negative clearance, increasing friction and drastically reducing bearing lifespan. In severe cases, it may cause the [[Ball (bearing)|bearing balls]] to bind and lock the wheels.<ref name="vegter-everything-about-bearing-spacers"/><ref name="smb-bearings-on-bearing-internal-clearance"/>{{efn-ua|name=under-or-over-tension-besides-proper-preload-both-reduce-bearing-life|See charts from NASA research and bearing manufacturers that illustrate bearing life as a function of internal clearance in radial ball bearings. At approximately {{nowrap|-0.01 mm}} clearance (representing optimal preload), bearing life reaches 100%. If under-tensioned (i.e. the axle bolt is not fully tightened), bearing life drops by nearly half with a positive clearance gap of {{nowrap|0.05 mm}}. Conversely, if over-tensioned (i.e. using a spacer that is too short), an additional negative clearance of just {{nowrap|-0.01 mm}} can reduce bearing life to 20%.<ref name="nasa-tech-report-on-internal-clearance-and-bearing-life-radial-ball-berings"/><ref name="jtekt-on-bearing-selection-04-bearing-fits-n-internal-clearance"/>
}} To address this, aluminum spacers are made in various lengths so skaters can match them to each wheel's exact dimensions.{{efn-ua|name=powerslide-store-product-wicked-precision-spacer-kit|
A [https://powerslide.com/products/precision-spacer-kit Wicked spacer kit] ([https://web.archive.org/web/20250621015120/http://web.archive.org/screenshot/https://powerslide.com/products/precision-spacer-kit archived]) includes assorted spacers of these lengths: {{nowrap|9.90 mm}}, {{nowrap|9.95 mm}}, {{nowrap|10.00 mm}} {{nowrap|10.05 mm}}, {{nowrap|10.10 mm}}, {{nowrap|10.15 mm}}, ({{nowrap|10.20 mm}}), {{nowrap|10.25 mm}}, {{nowrap|10.30 mm}}, {{nowrap|10.35 mm}}.
}}

[[File:Bearing Spacer Too Short - Axle Loose - inline skate wheel assembly - with labels.svg|thumb|right|upright=0.9|Loose axle w. short spacer]]

'''Loose axle''': To fix over-tension from short spacers, some skaters mistakenly loosen axle bolts, thinking it relieves excess preload. While this may let wheels spin freely, it causes the spacers and inner races to rattle and skid, producing clunking sounds. The inner races are no longer clamped, leading to [[#Bearing alignment|bearing misalignment]] and excessive wear from [[#Side load support|side loads]]. This creates cycles of over-preload and under-tension, worsening damage. ''Omitting spacers'' exacerbates the issue, potentially causing bearings to explode under strong side forces.<ref name="powell-svensson-inline-skating"/>{{rp|39–45}}<ref name="fireball-dragon-bearings-6-misconceptions-about-bearings"/><ref name="stoked-ride-shop-on-bearing-spacers-skateboards"/>

[[File:Bearing Spacer Too Long - inline skate wheel assembly - with labels.svg|thumb|right|upright=0.9|Slightly longer than optimal]]

'''Long spacer''': If a perfect spacer isn't available, a slightly longer spacer is preferred over a shorter one, to avoid over-tension and excessive bearing wear. While a longer spacer prevents preload by not pushing outer races against bearing abutments, it still allows the inner races and spacer to be securely clamped. Without preload, however, the outer races rely solely on [[Interference fit|press-fit]] against the bearing recesses, which may not hold under side loads. This can cause the outer races to shift, wear the hub's bearing recess, and lead to lateral wheel movement and clicking sounds during skating.<ref name="cryptonics-1995-patent-bearing-seat-to-eliminate-bearing-clicks"/><ref name="peterverdone-bearings-and-lubrication"/>
{{Clear}}

== Wheel setup ==

{{Main|Inline skate wheel setup}}

Wheel setup can refer to various aspects related to the selection and configuration of [[#Polyurethane wheels|wheels]]. The total number of wheels and their [[#Wheel diameter and profile|diameter]] are often expressed in the form {number of wheels} x {wheel diameter in mm}. For instance, a common [[#Recreational|recreational skate]] setup is 4x80mm, which means four wheels, each with a diameter of 80 millimeters. Wheel arrangement patterns are typically named according to the profile formed by the wheels at their contact points with the ground. In a [[#Flat setup|flat setup]], all wheels maintain contact with the ground simultaneously. A classic [[#Rockered setup|rockered setup]], by contrast, creates a banana-like profile along the bottom.<ref name="welch-demystify-inline-disciplines"/><ref name="markus-thierstein-wheel-rockering"/>

=== Flat setup ===

{{Main|Inline skate wheel setup#Flat setup}}

[[Image:Flat inline.svg|thumb|right|Flat wheel setup: 4x80mm]]

A flat setup is the most common wheel configuration used on inline skates. The majority of skates are sold with this arrangement. In a flat setup, all wheels make contact with the ground simultaneously when the skate is rolling on a level surface. While not as maneuverable as a [[#Rockered setup|rockered setup]], a flat setup excels in disciplines that prioritize speed, stability, and long-distance efficiency. It is the standard choice for [[Inline speed skating|speed skaters]] and [[Inline speed skating|marathon skaters]]. Flat wheel setups are typically noted in the format {number of wheels} x {wheel diameter in mm}. For example, a common recreational setup is 4x80mm or simply 4x80, indicating four wheels, each with a diameter of 80 millimeters.
<ref name="rollerblades-dryland-training-1985"/>{{rp|81–86}}<ref name="naomi-grigg-2014"/>{{rp|20–21}}<ref name="welch-demystify-inline-disciplines"/><ref name="zecoprzepraszam-inerview-powerside-on-trinity-165mm-195mm"/><ref name="skaters-mag-premier-issue-1990-on-getting-started-on-inlines"/>

=== Rockered setup ===

{{Main|Inline skate wheel setup#Rockered setup}}

[[File:Rockered Frame.svg|thumb|right|Rockering with frame hardware]]

A rockered setup, also called a "full rockered setup" or "banana rocker", involves altering the wheel alignment to increase maneuverability. In a four-wheel inline skate, this typically means raising the bottom of the front and rear wheels by about 2 millimeters, so that only the two middle wheels touch the ground when standing on a flat surface. This setup mimics the profile of an [[ice skate]] blade, and is known as the "banana" rocker after its curved profile.<ref name="rollerblades-dryland-training-1985"/>{{rp|81–86}}<ref name="liveabout-carlesa-williams-wheels-101"/><ref name="joyner-inline-hockey-1995"/>{{rp|28}}<ref name="markus-thierstein-wheel-rockering"/><ref name="endlessblading-geometry-of-inline-rocker-designs"/>

[[File:First Rollerblade brand inline skate from early 1980s-Rockered wheel setup-IMG 5651-FRD.png|thumb|right|upright=0.8|{{nowrap|70-70-70-70}} rockered]]

A rockered setup generally produces the opposite skating characteristics of a [[#Flat setup|flat setup]]. It offers much greater maneuverability and allows for quicker, easier turning. [[Freestyle slalom skating|Freestyle slalom skaters]] and [[Artistic roller skating|artistic inline skaters]] consider the rockered setup indispensable, as it enables gliding on just the front two wheels, the middle two wheels, or the rear two wheels, depending on the move. Having a [[#Frame dimensions|short frame]] in combination with a full rocker is optimum for achieving the highest maneuverability when skating. However, this setup makes it more difficult to maintain stability at high speeds, since the skater cannot glide on all four wheels at once and is more prone to wheel wobbles when skating in a straight line.<ref name="naomi-grigg-2014"/>{{rp|20–21}}<ref name="powell-svensson-inline-skating"/>{{rp|29–30}}<ref name="bladeville-wizard-frames-and-rest"/>

[[File:Full Rocker.svg|thumb|right|Rockering by sizing wheels: {{nowrap|76-80-80-76}}]]

A frame designed for a flat setup can still be converted into a rockered configuration by mounting [[#Wheel diameter and profile|smaller wheels]] at the front and rear. For example, a standard 4x80mm flat frame can become rockered by installing {{nowrap|76 mm}} wheels at the front and rear, while keeping {{nowrap|80 mm}} wheels in the middle. This customization creates a {{nowrap|2 mm}} height offset between the outer and middle wheels, mimicking the standard banana rocker profile. Skaters commonly notate mixed wheel sizes in millimeters, listed from the rear wheel to the front. The rockered configuration described above is typically written as "76-80-80-76".<ref name="naomi-grigg-2014"/>{{rp|20–21}}<ref name="markus-thierstein-wheel-rockering"/>

=== Natural rocker ===

{{Main|Inline skate wheel setup#Natural rocker}}

[[File:Worn Wheels-Labeda Gripper Asphalt 80mm 85A inline skate wheel-IMG 7242-bg-FRD.png|thumb|right|upright|Severely worn (left) vs moderately worn (right)]]

Natural rockering can develop naturally on [[#Flat setup|flat frames]] due to uneven wheel wear. Beginners often wear down front wheels faster, creating a natural hi-lo setup over time without needing different-sized wheels. Specific skating styles can also wear front and rear wheels more than the middle ones, forming a natural rocker. As wheels wear down, skaters can employ various [[#Wheel rotation|rotation strategies]] to either restore a flat setup or enhance the rocker.<ref name="markus-thierstein-wheel-rotation"/><ref name="rockin-frames-on-MIX4-and-165mm-mid-wheel-reductions"/><ref name="usenet-chen-FAQ-inline-wheels"/> Although natural rockering usually produces less than the standard {{nowrap|2 mm}} height difference, many skaters prefer this subtle profile. "Big-wheel" [[#Urban|urban skaters]] and wizard skating advocates often use factory-tuned, [[#Forward lean with a rocker|pre-rockered]] frames designed to mimic this naturally worn rocker with new wheels of same size. Wizard even named its classic four-wheel frame NR, after natural rocker.<ref name="endlessblading-balanced-rocker-on-4x90mm-trinity-frame"/><ref name="bladeville-wizard-frames-and-rest"/><ref name="rerolling-inline-boot-frame-wheel-setups"/><ref name="wizard-skating-product-NR-frames-NR90"/>

=== Front rocker ===

{{Main|Inline skate wheel setup#Front rocker}}

[[File:Front Rocker.svg|thumb|right|Front rocker wheel setup: {{nowrap|80-80-80-76}}]]

A front rocker setup raises only the front wheel, while the remaining three wheels stay in a flat configuration. This design serves as a compromise between a [[#Rockered setup|full rockered setup]] and a [[#Flat setup|flat setup]]. A skater achieves greater top speed and improved stability with less wheel wobble on this setup, compared to a full rockered setup, by [[#Striding and gliding|striding and gliding]] primarily on the three rear wheels. At the same time, the raised front wheel helps guide the skate over uneven terrain in urban environments.<ref name="mark-kempton-nottinghamskaters-on-wheel-setups"/><ref name="naomi-grigg-2014"/>{{rp|20–21}}<ref name="markus-thierstein-wheel-rockering"/>

=== Hi-lo setup ===

{{Main|Inline skate wheel setup#Hi-lo setup}}

[[File:TRUE Inline Hockey Skates-IMG 5253-single-heel to toe drop annotated-FRD.png|thumb|right|upright|{{nowrap|80-80-76-76}} hi-lo frame]]

The hi-lo setup, also known as "HiLo", is commonly found in [[#Hockey|hockey skates]]. Hi-lo is technically a [[#Flat setup|flat setup]], since all wheels maintain contact with the ground when the skate rests on a level surface. The term “hi-lo” refers not to the wheel contact profile, but to the orientation of the boot. It raises the heel and lowers the toe, creating a "heel-to-toe drop" that encourages a natural forward lean. This [[#Forward flex|forward flex]] promotes a more aggressive stance, enhances push-off power, and helps prevent backward falls. Unlike terms like [[#Flat setup|flat]] or [[#Rockered setup|rockered]], which describe how wheels touch the ground, “hi-lo” describes how the boot is angled forward.<ref name="mark-kempton-nottinghamskaters-on-wheel-setups"/><ref name="markus-thierstein-wheel-rockering"/><ref name="miller-get-rolling-2003"/>{{rp|57–59}}

[[File:Hi-lo setup on a hi-lo hockey frame with built-in heel lift.svg|thumb|right|Hi-lo hockey frame]]

This forward pitch can be achieved through a combination of frame design and wheel sizing. Some frames have built-in height offsets, resulting in a [[#Heel raise|heel raise]], common in hockey skates and standard on [[#165mm and 195mm frames|165mm]], [[#165mm and 195mm frames|195mm]], and [[#Trinity frames|Trinity]] mounts. However, this lift increases [[#Frame dimensions|ride height]], which can reduce stability. To counter this, hi-lo hockey frames use lower axle positions and smaller wheels toward the toe, keeping the front low while preserving forward lean and keeping ride height low. A typical hi-lo frame is annotated as "{{nowrap|80-80-76-76}}", combining better power transfer during push-offs with improved control and stability.<ref name="madison-rec-hockey-on-hi-lo-in-hockey-skates-vs-flat-setup"/><ref name="vegter-everything-about-frames"/><ref name="zecoprzepraszam-inerview-powerside-on-trinity-165mm-195mm"/><ref name="publow-speed-skating-1999"/>{{rp|311–314}}<ref name="powell-svensson-inline-skating"/>{{rp|18–24}}

Hi-lo setups with smaller front wheels are often marketed as providing quicker acceleration, while the larger rear wheels are said to help with achieving and maintaining top speed. While it is true that smaller wheels [[#Wheel diameter and profile|accelerate more quickly]] and larger wheels [[#Wheel diameter and profile|maintain speed]] more easily, these performance traits are not the reason for the hi-lo configuration. The smaller front wheels are used out of necessity - to lower the toe of the boot and preserve the forward pitch - rather than for their isolated performance benefits alone. In practice, the smaller front wheels trade top speed for a lower and more stable ride.<ref name="madison-rec-hockey-on-hi-lo-in-hockey-skates-vs-flat-setup"/><ref name="rerolling-inline-boot-frame-wheel-setups"/>{{efn-ua|name=misleading-hi-lo-marketing-on-small-accelerate-large-top-speed|
Misleading marketing is common, where hi-lo frames are advertised as offering quicker acceleration due to the smaller front wheels and higher top speeds thanks to the larger rear wheels. These claims often ignore the primary design purpose: creating forward lean by allowing the front of the boot to sit lower, which enhances forward pitch and skating posture. See for instance, [https://powerslide.com/blogs/technologies/hi-lo-frames Hi-lo Frames from Powerslide] (archived [https://web.archive.org/web/20250628194438/https://powerslide.com/blogs/technologies/hi-lo-frames here]), and [https://www.willies.co.uk/blogs/blog/a-guide-to-roller-hockey-wheels A Guide to Roller Hockey Wheels from Willies] (archived [https://web.archive.org/web/20250628194422/https://www.willies.co.uk/blogs/blog/a-guide-to-roller-hockey-wheels here]). If these marketing claims were entirely accurate, we would expect to see hockey frames with extremely small front wheels (e.g. {{nowrap|50 mm}}) and oversized rear wheels (e.g. {{nowrap|110 mm}}) to further enhance acceleration and top speed, without any design features to leverage vacated front space to pitch the boot forward. In reality, such frames do not exist.
}}

Many skaters casually refer to any mixed-size wheel configuration as a "rocker", which leads to the common but inaccurate use of the term "hi-lo rocker" to describe a standard hi-lo setup. This is a poor choice of words, as the hi-lo setup is a flat configuration. Some skaters also misuse "rocker" as a general synonym for "wheel setup", leading to additional confusion, such as referring to a flat setup as a "flat rocker".<ref name="markus-thierstein-wheel-rockering"/>{{efn-ua|name=common-mistakes-calling-hi-lo-setup-a-hi-lo-rocker|
Even professional skaters occasionally write "hi-lo rocker" when they mean "hi-lo flat". See [https://web.archive.org/web/20190416231922/https://skating.thierstein.net/Knowledge/Inline_Skating_Rollerblading_Knowledge_Rockering.html Thierstein], for instance. Redditors often write "hi-lo rocker", using the word "rocker" for any mixed-size wheel configuration. See [https://web.archive.org/web/20250629025314/http://web.archive.org/screenshot/https://www.reddit.com/r/rollerblading/comments/flucdd/why_do_some_inline_skates_have_a_front_wheel_that/ this], [https://web.archive.org/web/20250629025424/http://web.archive.org/screenshot/https://www.reddit.com/r/rollerblading/comments/aqrjsk/rockereable_frames/ this] and [https://web.archive.org/web/20250629025346/http://web.archive.org/screenshot/https://www.reddit.com/r/rollerblading/comments/ovx2s6/ice_skater_looking_for_rocker_advice/ this], for instance.
<!-- Do not remove archived links to Reddit citing Perennial_sources#RSPREDDIT. These are not references. These are used as anecdotal examples in a note. -->
}}{{efn-ua|name=common-mistakes-calling-flat-setup-a-flat-rocker|
Even professional skaters occasionally write "flat rocker" when they mean "flat setup". See [https://web.archive.org/web/20240913042918/https://www.thisissoul.com/blogs/hardware-insights/everything-about-wheels This Is Soul], [https://web.archive.org/web/20241213200037/https://bigwheelblading.com/demystifying-inline-skating-disciplines-a-complete-guide/ Big Wheel Blading], and Naomi's book, for instance.<ref name="naomi-grigg-2014"/>{{rp|20–21}}
}}

=== Alternatives to hi-lo ===

{{Main|Inline skate wheel setup#Alternatives to hi-lo}}

[[File:Hi-lo setup on a flat frame with progressively smaller wheels.svg|thumb|right|By sizing wheels: {{nowrap|80-78-76-74}}]]

[[File:Wheel rotation-pattern Hi Lo-for 4 wheel setup-inline skates.svg|thumb|right|upright=0.6|Hi-lo via rotation]]

[[File:Speedskate Hyper-bg removed.png|thumb|right|upright=0.7|Smaller 2nd wheel]]

Hi-lo frames are not the only approach to achieving a pitched boot with a low ride height. For instance, a [[#Hi-lo setup|hi-lo setup]] can be created using a standard [[#Flat setup|flat frame]] by fitting progressively smaller wheels from rear to front, with a typical hockey setup written as "{{nowrap|80-78-76-74}}". This arrangement produces a total heel-to-toe drop of {{nowrap|6 mm}} while maintaining full ground contact.<ref name="mark-kempton-nottinghamskaters-on-wheel-setups"/><ref name="rerolling-inline-boot-frame-wheel-setups"/> Instead of purchasing wheels in different diameters, a skater can gradually create a hi-lo setup through a [[Inline skate tuning#Wheel rotation|hi-lo rotation strategy]], by placing the most worn at the front and the least worn at the rear. This approach minimizes noticeable changes in ride height between rotations, offering a consistent skating feel over time.<ref name="markus-thierstein-wheel-rotation"/>

Similarly, speed skaters seek [[#Forward flex|forward flex]] while using [[#Wheel diameter and profile|larger wheels]], which raise [[#Frame dimensions|ride height]]. To low center of gravity, some [[#165mm and 195mm frames|165mm frames]] shift the second axle or use a smaller second wheel to lower the front.<ref name="cadomotus-on-165mm-195mm-boots-on-ice-blades"/><ref name="bladeville-inline-skate-frames"/> Similarly, the ROCKIN' MIX4 100/90 frame uses smaller middle wheels and adjusted axle positions to form a {{nowrap|100-90-90-100}} setup, keeping the boot closer to the ground.<ref name="rockin-frames-on-MIX4-and-165mm-mid-wheel-reductions"/><ref name="bladeville-wizard-frames-and-rest"/>

The [[#Trinity frames|Trinity system]] takes a different approach, with two front mounting points placed off-center, clearing space above the front wheels so they can sit closer to the boot. This allows setups like the Endless Trinity 90 with 3x110mm wheels to position the toe just {{nowrap|110 mm}} above the ground.<ref name="zecoprzepraszam-inerview-powerside-on-trinity-165mm-195mm"/><ref name="ricardo-lino-on-trinity-2017"/> Wizard Skating frames, using the [[#UFS frames|UFS standard]], achieve forward pitch by sloping the frame's mounting surface, despite using equal-sized wheels. However, UFS-based setups usually result in a higher ride height compared to Trinity.<ref name="bladeville-wizard-frames-and-rest"/><ref name="wizard-skating-product-NR-frames-NR90"/>

=== Forward lean with a rocker ===

{{Main|Inline skate wheel setup#Forward lean with a rocker}}

[[File:Forward lean with a rocker - Wizard NR Natural Rocker.svg|thumb|right|Wizard NR with Natural Rocker]]

A new variation of rockered skating emerged in the early 2010s, led by a new generation of [[Aggressive inline skating|aggressive skaters]] who rediscovered the benefits of [[#Rockered setup|rockered setups]], this time using larger wheels on longer frames.<ref name="bladeville-wizard-frames-and-rest"/><ref name="welch-demystify-inline-disciplines"/> Wizard Skating became a key influence. Its frames are made for flat [[#UFS frames|UFS boots]] but feature a sloped mounting surface that creates a slight [[#Forward flex|forward lean]], similar to a [[#Hi-lo setup|hi-lo flat setup]]. The Wizard NR series is "pre-rockered" with a mild banana rocker named after the [[#Natural rocker|natural rocker]]. The NR90 model uses four equal-sized wheels in a {{nowrap|90-90-90-90}} rockered layout.<ref name="wizard-skating-product-NR-frames-NR90"/>

[[File:Forward lean with a rocker - Ninja NN 90 V.m Rocker.svg|thumb|right|Ninja NN 90 with V.m Rocker]]

Similarly, the Endless Blading 90 frame is pre-rockered to support four {{nowrap|90 mm}} wheels. This setup, branded as the "Balanced Rocker", is another mild version of the banana rocker. The frame uses the [[#165mm and 195mm frames|165mm mounting]] standard, with a built-in forward lean.<ref name="endlessblading-product-endless-90-mk2-165mm-mounnt">{{cite web
|url=https://www.endlessblading.com/products/endless-90-mk2-frame?variant=45030241075425
|title=Endless 90 mk2 Frame (165mm mounting with Balance Rocker)
|website=Endless Blading
|url-status=live
|archive-url=https://web.archive.org/web/20250629211825/https://www.endlessblading.com/products/endless-90-mk2-frame?variant=45030241075425
|archive-date=2025-06-29
|access-date=2025-06-29
}}</ref> Another example is the Ninja NN 90 frame from NN Skates, which also features a pre-rockered design. It introduces NN Skates' proprietary "V.m Rocker", short for "modified V Rocker". The 165mm and [[#Trinity frames|Trinity]] versions come with built-in forward lean.<ref name="nn-skates-product-ninja-90-165mm-trinity-ufs-v_m_rocker">{{cite web
|url=https://nnskates.com/product/ninja-bundle/
|title=Ninja 90 frame 165mm/Trinity/UFS mountings with V.m Rocker
|website=NN Skates
|url-status=live
|archive-url=https://web.archive.org/web/20250629211847/https://nnskates.com/product/ninja-bundle/
|archive-date=2025-06-29
|access-date=2025-06-29
}}</ref>

[[File:Forward lean with a rocker - Rotated to show level frame top.svg|thumb|right|Artificially pivoted view]]

All of these "pre-rockered frames" are variations of the [[#Rockered setup|full rockered setup]], combined with built-in [[#Forward flex|forward flex]]. However, they are sometimes marketed using simplified illustrations that "horizon-correct" the top surface of the frame, showing the boot level and the skate pivoting primarily on the third wheel. This artificial stance is often described as a "V-shaped" wheel-contact profile, a "V rocker", or a "3rd-wheel down" configuration. In practice, however, skaters do not glide on a single wheel. Instead, they roll on two wheels at a time, such as the 2nd and 3rd, where the boot naturally tilts forward like a hi-lo setup.<ref name="endlessblading-geometry-of-inline-rocker-designs"/><ref name="bladeville-wizard-frames-and-rest"/><ref name="nn-skates-faqs-v-vm-rocker-165mm-trinity-ufs"/><ref name="wizard-skating-product-NR-frames-NR90"/>

Some skaters therefore refer to this combination of forward pitch and rocker as the "hi-lo rocker" or "full hi-lo rocker". However, these terms can be confusing, especially since "hi-lo rocker" is also used colloquially to describe standard hi-lo setups. At present, there is no consistent term for this combination of banana rocker and forward lean in a pre-rockered frame.<ref name="markus-thierstein-wheel-rockering"/><ref name="markus-thierstein-wheel-rotation"/>{{efn-ua|name=common-mistakes-calling-hi-lo-setup-a-hi-lo-rocker}}{{efn-ua|name=common-mistakes-calling-flat-setup-a-flat-rocker}}

=== Anti-rocker setup ===

{{Main|Inline skate wheel setup#Anti-rocker setup}}

[[File:Anti rocker setup.svg|thumb|right|Typical anti-rocker setup]]

The anti-rocker setup is the most widely used wheel configuration in [[#Aggressive|aggressive skates]]. It gets its name from being the opposite of a [[#Rockered setup|rockered setup]]. In an anti-rocker configuration, the two middle wheels are raised ''off the ground'', leaving only the front and rear wheels to make contact on flat surfaces. The middle wheels are typically spaced farther apart than in standard four-wheel setups, and are often made of harder materials with minimal grip. These hard wheels are commonly referred to as [[#Aggressive|grindwheels]], antirockers, or anti-rocker wheels.<ref name="markus-thierstein-wheel-rockering"/><ref name="vegter-everything-about-grindwheels"/> They are designed for one task alone: to make [[Aggressive inline skating|grinding]] on ledges and rails easier.<ref name="bladeville-components-of-aggressive-skates"/><ref name="vegter-everthing-about-grooves"/>

=== Freestyle setup ===

[[File:Freestyle setup.svg|thumb|right|Freestyle frame]]

{{Main|Inline skate wheel setup#Freestyle setup}}

The freestyle setup is another wheel configuration favored by [[Aggressive inline skating|aggressive skaters]]. Despite the name, it is unrelated to [[Freestyle slalom skating|freestyle slalom]] around cones or freestyle skating on flat ground free of street obstacles. This setup features ''only two outer wheels'', with the middle portion of the frame replaced by solid material that resembles an extended [[#Aggressive|H-block]], optimized for grinding.<ref name="bladeville-components-of-aggressive-skates"/><ref name="vegter-everything-about-grindwheels"/>

[[File:Freestyle setup using Fifty-50 and juice blocks.svg|thumb|right|Freestyle via juice blocks]]

Fifty-50's Balance Frame introduced a convertible design that can use either grindwheels or juice blocks in the center. When juice blocks are installed as grind blocks, they fill the space between the frame walls, extending the H-block to form a smooth, solid grinding surface. This transforms the Balance Frame from an [[#Anti-rocker setup|anti-rocker setup]] into a freestyle setup.<ref name="back-to-blading-history-of-50-50-freestyle-frame-juice-blocks"/><ref name="vegter-everything-about-grindwheels"/>

==See also==

* [[Roller skates]] - Inline skates are technically a type of roller skate, but roller skates now exclusively refer to quad skates.
* [[Ice skates]] - Inline skates traces back to the origin of ice skates, as a way to glide on non-ice surfaces, with wheels.
* [[Inline skating]] - Different types of inline skates reflect needs specific to different inline skating disciplines.
* [[Roller sports]] - Inline skating is one of many sports that use human-powered roller vehicles, in this case, inline skates.
{{Clear}}

==Notes==

{{notelist-ua}}

==References==

{{reflist|30em|refs=

<ref name="museum-of-roller-skating-history-of-roller-skating-1997">{{cite book
|title=The History of Roller Skating
|last1=Turner
|first1=James
|last2=Zaidman
|first2=Michael
|date=1997
|location=Lincoln, Nebraska
|publisher=National Museum of Roller Skating
|isbn=0965819205
|url=https://www.rollerskatingmuseum.org/product-page/the-history-of-roller-skating <!-- encourage readers to get this book from the Museum itself at $15 (2024) instead of paying for x3 markup at Amazon and elsewhere -->
}} Illustrated with museum collections and archives.
</ref>

<ref name="ols-history-skating-1760-to-today">{{cite web
|url=https://online-skating.com/featured-articles/the-history-of-skating-from-1760-till-today/
|title=The History of Skating from 1760 till Today
|website=OLS Online Skating
|date=12 November 2023
|url-status=live
|archive-url=https://web.archive.org/web/20241128072050/https://online-skating.com/featured-articles/the-history-of-skating-from-1760-till-today/
|archive-date=2024-11-28
}}</ref>

<ref name="system-of-figure-skating-1880">{{cite book
|url=https://books.google.com/books?id=vaBGAQAAMAAJ
|title=A System of Figure-skating: Being the Theory and Practice of the Art as Developed in England with a Glance at Its Origin and History
|pages=4–7
|location=London
|publisher=Horace Cox
|year=1880
|access-date=2024-11-24
|first1=H.E.
|last1=Vandervell
|first2=T. Maxwell
|last2=Witham
}}</ref>

<ref name="museum-of-roller-skating-history-of-inline">{{cite web
|url=http://rollerskatingmuseum.com/inline.html
|title=The History of Inline Skating
|website=National Museum of Roller Skating
|url-status=dead
|archive-url=https://web.archive.org/web/20190410214014/http://rollerskatingmuseum.com/inline.html
|archive-date=2019-04-10
}}</ref>

<ref name="international-companies-vol34-rollerblade">{{cite book
|url=https://archive.org/details/internationaldir0000unse_r5m3
|title=International Directory of Company Histories
|volume=34
|date=2000
|article=Rollerblade, Inc.
|pages=388–392
|location=Detroit
|publisher=St. James Press
|author-first1=Kathleen
|author-last1=Peippo
|author-first2=Nelson
|author-last2=Rhodes
|access-date=2024-12-23
}}</ref>

<ref name=nyt-1990-craze-outsprint>{{cite news
|author=<!--not stated-->
|date=1990-08-07
|title=A Craze May Outsprint Its Creator
|url=https://www.nytimes.com/1990/08/07/business/a-craze-may-outsprint-its-creator.html
|url-status=live
|work=The New York Times
|location=New York
|archive-url=https://web.archive.org/web/20140321231120/https://www.nytimes.com/1990/08/07/business/a-craze-may-outsprint-its-creator.html
|archive-date=2014-03-21
|access-date=2024-12-22
}}</ref>

<ref name="mit-inventor-of-the-week-on-scott-olson-brennan-olson">{{cite web
| title = Inventor of the Week Archive: Scott & Brennan Olson (spelling corrected per rowbike.com -ed.)
| publisher = MIT School of Engineering
| date = August 1997
| url = http://web.mit.edu/invent/iow/Inline.html
| archive-url = https://web.archive.org/web/20030302044906/http://web.mit.edu/invent/iow/Inline.html
| url-status = dead
| archive-date = 2003-03-02
| access-date = 2007-02-25
}}</ref>

<ref name="shevelson-golden-days-of-skating-skaters-mag-premier-issue-1990">{{cite magazine
| author      = Paul A. Dunn and Sharry Beck Paprocki
| title       = Joseph Shevelson interviewed by Paul A. Dunn and Sharry Beck Paprocki on the Golden Days of Skating
| url         = https://www.networkistics.com/sample/asufoundation/wp-content/uploads/2018/06/1990-July-Roller-Skater.pdf
| magazine    = Skaters
| volume      = 1
| number      = 1: Premier Issue
| date        = June–July 1990
| pages        = 12–18
| location    = Mt. Morris, Ill.
| publisher   = CFW Enterprises, Inc
| archive-url = https://web.archive.org/web/20240619204436/https://www.networkistics.com/sample/asufoundation/wp-content/uploads/2018/06/1990-July-Roller-Skater.pdf
| archive-date = 2024-06-19
| access-date = 2024-12-20
}}</ref>

<ref name="skaters-mag-premier-issue-1990-on-getting-started-on-inlines">{{cite magazine
| author      = Chris Morris
| title       = In-Lines: Getting Started - Tips for the beginner
| url         = https://www.networkistics.com/sample/asufoundation/wp-content/uploads/2018/06/1990-July-Roller-Skater.pdf
| magazine    = Skaters
| volume      = 1
| number      = 1: Premier Issue
| date        = June–July 1990
| pages        = 32–36
| location    = Mt. Morris, Ill.
| publisher   = CFW Enterprises, Inc
| archive-url = https://web.archive.org/web/20240619204436/https://www.networkistics.com/sample/asufoundation/wp-content/uploads/2018/06/1990-July-Roller-Skater.pdf
| archive-date = 2024-06-19
| access-date = 2024-12-20
}}</ref>

<ref name="skaters-mag-premier-issue-1990-on-quad-vs-inline">{{cite magazine
| author      = Pat Parnell
| title       = Quads vs. In-Lines
| url         = https://www.networkistics.com/sample/asufoundation/wp-content/uploads/2018/06/1990-July-Roller-Skater.pdf
| magazine    = Skaters
| volume      = 1
| number      = 1: Premier Issue
| date        = June–July 1990
| pages        = 37–42
| location    = Mt. Morris, Ill.
| publisher   = CFW Enterprises, Inc
| archive-url = https://web.archive.org/web/20240619204436/https://www.networkistics.com/sample/asufoundation/wp-content/uploads/2018/06/1990-July-Roller-Skater.pdf
| archive-date = 2024-06-19
| access-date = 2024-12-20
}}</ref>

<ref name="fried-cassorla-inline-ultimate-guide-1995">{{cite book
|url=https://books.google.com/books?id=BNXZAAAAMAAJ
|title=In-line Skating: The Ultimate How-to Guide
|publisher=Prima Publishing
|location=California
|year=1995
|isbn=1559586486
|access-date=2025-01-11
|first1=Albert
|last1=Fried-Cassorla
|others=Fried-Cassorla authored a 1976 book on skateboarding before this 1995 book on inline skating: ''The Skateboarder's Bibble: technique, equipment, stunts, terms, etc.''
}} [https://archive.org/details/inlineskatingult00frie Alt URL]</ref>

<ref name="powell-svensson-inline-skating">{{cite book
|url=https://books.google.com/books?id=T-IvswEACAAJ
|title=In-line Skating
|location=Champaign, Ill.
|publisher=Human Kinetics
|year=1998
|isbn=0880116595
|access-date=2024-12-23
|first1=Mark
|last1=Powell
|first2=John
|last2=Svensson
}}</ref>

<ref name="miller-get-rolling-2003">{{cite book
|url=https://books.google.com/books?id=2ytIseKpbMQC
|title=Get Rolling: The Beginner's Guide to In-line Skating
|edition=3rd
|location=California
|publisher=Get Rolling Books
|year=2003
|isbn=0963219634
|access-date=2025-01-02
|first1=Liz
|last1=Miller
}}</ref>

<ref name="naomi-grigg-2014">{{cite book
|url=https://books.google.com/books?id=6XHcoAEACAAJ
|title=The Art of Falling: Freestyle Slalom Skating
|location=San Francisco
|publisher=Patson Media
|year=2014
|isbn=9780692227374
|first1=Naomi
|last1=Grigg
}}</ref>

<ref name="feineman-wheel-excitement">{{cite book
|url=https://books.google.com/books?id=AluwOAAACAAJ
|title=Wheel Excitement
|location=New York
|publisher=Hearst Books
|year=1991
|isbn=0688108148
|access-date=2024-12-23
|first1=Neil
|last1=Feineman
}}</ref>

<ref name="gutman-catching-air-2004">{{cite book
|url=https://books.google.com/books?id=_s_RKqCs1oQC
|title=Catching Air: the excitement and daring of individual action sports - snowboarding, skateboarding, BMX biking, in-line skating
|location=New York
|publisher=Citadel Press
|year=2004
|isbn=0806525401
|access-date=2025-01-04
|first1=Bill
|last1=Gutman
|first2=Shawn
|last2=Frederick
}}</ref>

<ref name="publow-speed-skating-1999">{{cite book
|url=https://books.google.com/books?id=eCXgUEldHnMC
|title=Speed on Skates: a complete technique, training and racing guide for in-line and ice skaters
|publisher=Human Kinetics
|location=Champaign, Ill.
|year=1999
|isbn=0880117214
|access-date=2025-01-05
|first1=Barry
|last1=Publow
}}</ref>

<ref name="welch-demystify-inline-disciplines">{{cite web
|url=https://bigwheelblading.com/demystifying-inline-skating-disciplines-a-complete-guide/
|title=Demystifying Inline Skating Disciplines: A Complete Guide
|website=Big Wheel Blading
|first1=Jan
|last1=Welch
|date=21 June 2023
|url-status=live
|archive-url=https://web.archive.org/web/20241213200037/https://bigwheelblading.com/demystifying-inline-skating-disciplines-a-complete-guide/
|archive-date=2024-12-13
|access-date=2025-01-04
}}</ref>

<ref name="vegter-names-in-inline-skating">{{cite web
|first1=Ivo
|last1=Vegter
|title=The Strange History Behind Inline Skating // Many Names
|others=See video transcript on history on different types of inline skates and skating, including naming, relationships and differences: Rollerblade, Bladers, skeeler, Partines, Roller Freestyle, Recreational inline, soft boot, hard boot, Slalom inline, Freestyle inline, Urban inline, Flow inline, Tri-Skates, and Aggressive inline. The history intro also discusses quad skates, skateboarding and their shared history with inline skating, including wheels, axles and ISO 608 bearings.
|url=https://www.youtube.com/watch?v=_hzflhM7Qmw
|website=thisissoul.com
|publisher=This is Soul
|language=en
|format=video
|date=2024-12-09
}}</ref>

<ref name="vegter-hybrid-hard-boot-soft-boot">{{cite web
|first1=Ivo
|last1=Vegter
|title=Hardboot VS Softboot
|others=See video transcript on how recreational skates range from inexpensive soft boots with exoskeletons, to mid-end hard boots, to high-end (hybrid) soft boots with endoskeleton - and varied levels of ankle support
|url=https://www.youtube.com/watch?v=eSoIp1z_Uls
|website=thisissoul.com
|publisher=This is Soul
|language=en
|format=video
|date=2021-06-27
}}</ref>

<ref name="vegter-everthing-about-grooves">{{cite web
|first1=Ivo
|last1=Vegter
|title=Everything About Grooves
|others=See video transcript on history of frame grooves, soulplates, backslide groove, Rollerblade Lightning, Roces Majestic 12 (M12), UFS mounting holes, split, wheel protection, height of grooves, radius of grooves, etc.
|url=https://www.youtube.com/watch?v=wQejh4f6Aco
|website=thisissoul.com
|publisher=This is Soul
|language=en
|format=video
|date=2021-08-31
}}</ref>

<ref name="vegter-everything-about-frames">{{cite web
|url=https://www.thisissoul.com/blogs/hardware-insights/everything-about-frames
|title=Everything about Frames
|website=This Is Soul
|date=4 January 2022
|url-status=live
|archive-url=https://web.archive.org/web/20250115160634/https://www.thisissoul.com/blogs/hardware-insights/everything-about-frames
|archive-date=2025-01-15
|access-date=2025-01-16
}}</ref>

<ref name="vegter-everything-about-grindwheels">{{cite web
|url=https://www.thisissoul.com/blogs/hardware-insights/everything-about-grindwheels
|title=Everything about Grindwheels
|website=This Is Soul
|date=29 May 2023
|url-status=live
|archive-url=https://web.archive.org/web/20250122164054/https://www.thisissoul.com/blogs/hardware-insights/everything-about-grindwheels
|archive-date=2025-01-22
|access-date=2025-01-22
}}</ref>

<ref name="vegter-naming-freestyle-aggro-street-skating">{{cite web
|first1=Ivo
|last1=Vegter
|title=Freestyle vs Aggressive vs Street skating // Terminology
|others=Discussion on freestyle inline skating, aggressive inline skating, and their relationship to BMX biking and skateboarding. This video explains how various disciplines acquired their names. It also clarifies labels under which skates suitable for these disciplines are marketed.
|url=https://www.youtube.com/watch?v=TGCQP31UKK0
|website=thisissoul.com
|publisher=This is Soul
|language=en
|format=video
|date=2019-09-29
}}</ref>

<ref name="powerslide-hard-soft-hybrid-boots">{{cite AV media
|first1=Matthias
|last1=Knoll
|first2=Jürgen
|last2=Pfitzner
|title=Inline skate differences - hard boot, soft boot, hybrid ?!
|others=Discourses on hard boot vs. soft boot with exoskeleton vs. hybrid boot with endoskeleton
|url=https://www.youtube.com/watch?v=x5UmJ7qZw-U
|via=YouTube
|publisher=Powerslide
|language=en
|format=video
|date=2018-07-20
}}</ref>

<ref name="rollerblades-dryland-training-1985">{{cite book <!-- book not recorded on Google Books nor Inernet archive -->
|url=https://www.amazon.com/ROLLERBLADES-Dryland-Training-Ice-Hockey/dp/B000L0Z73E
|archive-url=https://web.archive.org/web/20250108034629/http://web.archive.org/screenshot/https://www.amazon.com/ROLLERBLADES-Dryland-Training-Ice-Hockey/dp/B000L0Z73E
|archive-date=2025-01-08
|title=Rollerblades: Dryland Training for Ice Hockey
|publisher=Ole's Innovative Sports
|location=Minneapolis, Minn.
|year=1985
|access-date=2025-01-08
|editor-first1=Chris
|editor-last1=Middlebrook
|others=Chapters by Randy Gregg, Jack Blatherwick, Laura Stamm, Brad Buetow, Scott Olson, Brennan Olson
}}</ref>

<ref name="joyner-inline-hockey-1995">{{cite book
|url=https://books.google.com/books?id=kJD-pT_XOEkC
|title=In-line Roller Hockey: The Official Guide and Resource Book
|location=Chicago
|publisher=Contemporary Books
|year=1995
|isbn=0809234483
|access-date=2025-01-01
|first1=Stephen Christopher
|last1=Joyner
}}</ref>

<ref name="rerolling-inline-boot-frame-wheel-setups">{{cite AV media
|title=All The Inline Skating Setups I've Tried So Far - My Setup Journey
|others=See transcript for discussions on inline skate setups with different combinations of boots, frames, wheels and wheel setups
|url=https://www.youtube.com/watch?v=EMNHI0gFdxA
|via=YouTube
|publisher=Rerolling Inline
|language=en
|format=video
|date=2023-04-18
|url-status=live
|archive-url=https://web.archive.org/web/20250427105326/https://www.youtube.com/watch?v=EMNHI0gFdxA
|archive-date=2025-04-27
|access-date=2025-05-04
}}</ref>

<ref name="markus-thierstein-wheel-rockering">{{cite web
|url=https://skating.thierstein.net/Knowledge/Inline_Skating_Rollerblading_Knowledge_Rockering.html
|title=Inline Skating Knowledge: Rockering
|first1=Markus
|last1=Thierstein
|website=Skating Thierstein
|url-status=live
|archive-url=https://web.archive.org/web/20190416231922/https://skating.thierstein.net/Knowledge/Inline_Skating_Rollerblading_Knowledge_Rockering.html
|archive-date=2019-04-16
|access-date=2025-01-20
}}</ref>

<ref name="inline-warehouse-choose-urban-skates">{{cite web
|url=https://www.inlinewarehouse.com/How_to_Choose_Urban_Inline_Skates/catpage-HTCURB.html
|title=How to Choose Urban Inline Skates
|website=Inline Warehouse
|url-status=live
|archive-url=https://web.archive.org/web/20250126050710/https://www.inlinewarehouse.com/How_to_Choose_Urban_Inline_Skates/catpage-HTCURB.html
|archive-date=2025-01-26
|access-date=2025-01-26
}}</ref>

<ref name="inline-warehouse-frame-buying-guide">{{cite web
|url=https://www.inlinewarehouse.com/fitlc/frames/skate-frame-buying-guide.html
|title=Inline Skate Frame Buying Guide
|website=Inline Warehouse
|url-status=live
|archive-url=https://web.archive.org/web/20250205030112/https://www.inlinewarehouse.com/fitlc/frames/skate-frame-buying-guide.html
|archive-date=2025-02-05
|access-date=2025-02-05
}}</ref>

<ref name="xinhaidude-carbon-fiber-inline-skates">{{cite web
|url=https://xinhaidude.com/2024/10/21/what-are-carbon-fiber-inline-skates/
|title=What are Carbon-fiber Inline Skates?
|date=2024-10-21
|website=Xinhai Dude
|url-status=live
|archive-url=https://web.archive.org/web/20250119190811/https://xinhaidude.com/2024/10/21/what-are-carbon-fiber-inline-skates/
|archive-date=2025-01-19
|access-date=2025-01-19
}}</ref>

<ref name="xinhaidude-how-to-inline-skate">{{cite web 
|url=https://xinhaidude.com/2022/04/24/how-to-inline-skate/
|title=How to Inline Skate
|date=2022-04-24
|website=Xinhai Dude
|url-status=live
|archive-url=https://web.archive.org/web/20241118192629/https://xinhaidude.com/2022/04/24/how-to-inline-skate/
|archive-date=2024-11-18
|access-date=2025-01-03
}}</ref>

<ref name="skamidan-inline-skating-in-brief">{{cite web
|url=https://www.skamidan.com/en/blogs/fitness-inline-skating/was-ist-inline-skating-wissenswertes-und-grundlagen
|title=What is Inline Skating – Inline Skating in Brief
|website=SkaMiDan – Skating School & Skateshop
|date=16 November 2023
|url-status=live
|archive-url=https://web.archive.org/web/20250109012553/https://www.skamidan.com/en/blogs/fitness-inline-skating/was-ist-inline-skating-wissenswertes-und-grundlagen
|archive-date=2025-01-09
|access-date=2025-02-09
}}</ref>

<ref name="back-to-blading-origin-of-UFS-and-mounting-standards">{{cite AV media
|title=What is UFS? Past, Present and Future of frame mounting
|others=See video transcript on discussions on origin of not just UFS, but also of original rivet mounts in Rollerblade TRS, and K2 Fatty. Aggressive makers rallied around the Salomon boot with a flat sole and created UFS standard.
|url=https://www.youtube.com/watch?v=ZqR-qycC_QI
|via=YouTube
|publisher=Back to Blading
|language=en
|format=video
|date=2018-10-25
|url-status=live
|archive-url=https://web.archive.org/web/20250216220305/https://www.youtube.com/watch?v=ZqR-qycC_QI
|archive-date=2025-02-16
|access-date=2025-05-04
}}</ref>

<ref name="bladeville-inline-skate-frames">{{cite web
|url=https://bladeville.com/in-line/frames.html
|title=Inline Skate Frames
|website=Bladeville
|url-status=live
|archive-url=https://web.archive.org/web/20250217040042/https://bladeville.com/in-line/frames.html
|archive-date=2025-02-17
|access-date=2025-02-17
}} Widen browser width for desktop rendering mode, to see descriptions of frame standards: 165mm, 195mm, UFS and Trinity.</ref>

<ref name="le-roller-en-ligne-interview-alex-bont">{{cite web
|url=https://www.rollerenligne.com/dossier/interview-with-alexander-bont/
|title=Interview with Alexander Bont, owner of the Australian Brand
|date=2015-07-22
|website=Le Roller en Ligne
|url-status=live
|archive-url=https://web.archive.org/web/20250217194404/https://www.rollerenligne.com/dossier/interview-with-alexander-bont/
|archive-date=2025-02-17
|access-date=2025-02-17
}}</ref>

<ref name="bladeville-glossary-terms-rollerblading">{{cite web
|url=https://bladeville.com/blog/glossary-of-terms-in-rollerblading
|title=Glossary of terms in rollerblading
|website=Bladeville
|url-status=live
|archive-url=https://web.archive.org/web/20250217185447/https://bladeville.com/blog/glossary-of-terms-in-rollerblading
|archive-date=2025-02-17
|access-date=2025-02-17
}}</ref>

<ref name="zecoprzepraszam-inerview-powerside-on-trinity-165mm-195mm">{{cite web
|url=https://zecoprzepraszam.wordpress.com/2016/01/15/trinity-system-incoming-revolution/
|title=Trinity system – incoming revolution
|date=2016-01-15
|others=Interview with Powerslide on the upcoming Trinity mounting system (2016) with respect to popular 165mm and 195mm mounting systems.
|website=Że co, przepraszam?!
|url-status=live
|archive-url=https://web.archive.org/web/20250217184917/https://zecoprzepraszam.wordpress.com/2016/01/15/trinity-system-incoming-revolution/
|archive-date=2025-02-17
|access-date=2025-02-17
}}</ref>

<ref name="le-roller-en-ligne-on-165mm-195mm-triskates">{{cite web
|url=https://www.rollerenligne.com/materiel/is-2015-the-comeback-year-of-165-mm-mounting/
|title=Is 2015 the comeback year of 165mm mounting?
|date=2015-04-10
|website=Le Roller en Ligne
|url-status=live
|archive-url=https://web.archive.org/web/20250217184945/https://www.rollerenligne.com/materiel/is-2015-the-comeback-year-of-165-mm-mounting/
|archive-date=2025-02-17
|access-date=2025-02-17
}}</ref>

<ref name="powerslide-different-mounting-systems">{{cite AV media
|first1=Pascal
|last1=Briand
|title=Pit Stop - Discover the different mounting systems of inline skates
|others=Covers Trinity, 195mm, UFS, 165mm, and riveted mounting systems
|url=https://www.youtube.com/watch?v=PbjmtEEb5lo
|via=YouTube
|publisher=Powerslide
|language=en
|format=video
|date=2021-08-18
}}</ref>

<ref name="cadomotus-on-165mm-195mm-boots-on-ice-blades">{{cite web
|url=https://www.cadomotus.com/en/blogs/cadowiki/your-inline-boot-on-an-ice-blade/
|title=Mounting your inline boot on an ice blade? Why that doesn't fit (unfortunately)
|date=2020-12-29
|others=discusses 165mm and 195mm mounting standards, and explains why a 195mm boot will not fit a standard ice blade tailored to average heel-to-ball distances.
|website=Cádomotus
|url-status=live
|archive-url=https://web.archive.org/web/20250301205442/https://www.cadomotus.com/en/blogs/cadowiki/your-inline-boot-on-an-ice-blade/
|archive-date=2025-03-01
|access-date=2025-03-01
}}</ref>

<ref name="xinhaidude-ps-trinity-reign-as-big-wheel-urban-skate">{{cite web
|url=https://xinhaidude.com/2024/11/16/set-up-reign-ares-as-big-wheel-skates-for-urban-marathons/
|title=Reign Ares as big-wheel skates for urban marathons
|date=2024-11-16
|website=Xinhai Dude
|url-status=live
|archive-url=https://web.archive.org/web/20250302200028/https://xinhaidude.com/2024/11/16/set-up-reign-ares-as-big-wheel-skates-for-urban-marathons/
|archive-date=2025-03-02
|access-date=2025-03-02
}}</ref>

<ref name="skatingmagic-on-frames-buying-guide">{{cite web
|url=https://skatingmagic.com/inline-skate-frame-buying-guide/
|title=Inline Skate Frame Buying Guide
|date=2021-07-31
|website=Skating Magic
|url-status=live
|archive-url=https://web.archive.org/web/20250305231228/https://skatingmagic.com/inline-skate-frame-buying-guide/
|archive-date=2025-03-05
|access-date=2025-03-05
}}</ref>

<ref name="loco-skates-on-frame-mounting">{{cite web
|url=https://www.locoskates.com/blogs/help-articles/frame-mounting-for-inline-skates-explained
|title=Frame Mounting for Inline Skates - Everything You Need To Know
|date=2024-05-30
|website=Loco Skates
|url-status=live
|archive-url=https://web.archive.org/web/20250120134002/https://www.locoskates.com/blogs/help-articles/frame-mounting-for-inline-skates-explained
|archive-date=2025-01-20
|access-date=2025-03-05
}}</ref>

<ref name="vegter-everthing-about-wheels">{{cite web
|url=https://www.thisissoul.com/blogs/hardware-insights/everything-about-wheels
|first1=Ivo
|last1=Vegter
|title=Everything about wheels
|website=This Is Soul
|date=4 January 2022
|url-status=live
|archive-url=https://web.archive.org/web/20240913042918/https://www.thisissoul.com/blogs/hardware-insights/everything-about-wheels
|archive-date=2024-09-13
|access-date=2025-03-07
}}</ref>

<ref name="le-roller-en-ligne-on-inline-wheels">{{cite web
|url=https://www.rollerenligne.com/materiel/anatomy-of-an-inline-skate-wheel/
|title=Anatomy of an inline skate wheel
|date=2020-11-03
|website=Le Roller en Ligne
|url-status=live
|archive-url=https://web.archive.org/web/20250308181611/https://www.rollerenligne.com/materiel/anatomy-of-an-inline-skate-wheel/
|archive-date=2025-03-08
|access-date=2025-03-08
}}</ref>

<ref name="powerslide-download-guides-frames">{{cite web
|url=https://powerslide.com/cdn/shop/files/PS_FRAMES_INFOGRAPHICS.pdf
|title=Powerslide Frames Guide
|website=Powerslide
|url-status=live
|archive-url=https://web.archive.org/web/20240528091917/https://powerslide.com/cdn/shop/files/PS_FRAMES_INFOGRAPHICS.pdf
|archive-date=2024-05-28
|access-date=2025-03-08
}}</ref>

<ref name="usenet-chen-FAQ-inline-bearings">{{cite newsgroup
 | title = Skate FAQs: The Bearing Maintenance File
 | author = Anthony D. Chen
 | date = 1992-05-02
 | newsgroup = rec.skate
 | url = http://skatefaq.adchen.com/bearings.html
 | url-status=live
 | access-date = 2025-05-09
 | archive-url = https://archive.today/20250509225643/http://skatefaq.adchen.com/bearings.html
 | archive-date = 2025-05-09
}}</ref>

<ref name="powerslide-download-guides-bearings-by-wicked">{{cite web
|url=https://powerslide.com/cdn/shop/files/BEARING_GUIDE_pdf_compressed_PIM.pdf
|title=Powerslide/Wicked Bearing Guide
|website=Powerslide
|url-status=live
|archive-url=https://web.archive.org/web/20240519161144/https://powerslide.com/cdn/shop/files/BEARING_GUIDE_pdf_compressed_PIM.pdf?v=5584448427062936883
|archive-date=2024-05-19
|access-date=2025-05-09
}}</ref>

<ref name="usenet-chen-FAQ-abec-hype">{{cite web
|url=http://www.skatefaq.com/articles/abec-hype.html
|title=ABEC = HYPE?
|first1=Anthony D.
|last1=Chen
|access-date=15 September 2014
|archive-date=15 March 2018
|archive-url=https://web.archive.org/web/20180315175329/http://www.skatefaq.com/articles/abec-hype.html
|url-status=dead
}}</ref>

<ref name="skf-group-rolling-bearings-1152-pages-2018">{{cite web
|url=https://cdn.skfmediahub.skf.com/api/public/0901d196802809de/pdf_preview_medium/0901d196802809de_pdf_preview_medium.pdf
|title=Rolling Bearings
|others=A 1,152 document published by SKF Group
|date=October 2018
|website=SKF Group
|url-status=live
|archive-url=https://web.archive.org/web/20250407180349/https://cdn.skfmediahub.skf.com/api/public/0901d196802809de/pdf_preview_medium/0901d196802809de_pdf_preview_medium.pdf
|archive-date=2025-04-07
|access-date=2025-05-13
}}</ref>

<ref name="bones-bearings-history-by-george-powell">{{cite web
|url=https://bonesbearings.com/products/history/
|title=Bones® Bearings History
|first1=George A.
|last1=Powell
|website=Bones Bearings
|url-status=live
|archive-url=https://web.archive.org/web/20080510154036/https://bonesbearings.com/products/history/
|archive-date=2008-05-10
|access-date=2025-05-16
}}</ref>

<ref name="bones-bearings-maintaining-your-bones-bearings">{{cite web
|url=https://bonesbearings.com/support/maintenance/
|title=Maintaining your Bones® Bearings
|first1=George A.
|last1=Powell
|website=Bones Bearings
|url-status=live
|archive-url=https://web.archive.org/web/20080510154411/http://bonesbearings.com/support/maintenance/
|archive-date=2008-05-10
|access-date=2025-05-16
}}</ref>

<ref name="inmoveskates-roller-skate-bearings">{{cite web
|url=https://www.inmoveskates.com/learning-center/about-bearings/guide-to-roller-skate-bearings-2023
|title=Guide to roller and inline skate bearings 2024
|date=2023-04-20
|first1=Alex
|last1=Shulgan
|website=InMove Skates
|url-status=live
|archive-url=https://web.archive.org/web/20250511175321/https://www.inmoveskates.com/learning-center/about-bearings/guide-to-roller-skate-bearings-2023
|archive-date=2025-05-11
|access-date=2025-05-16
}}</ref>

<ref name="bones-bearings-skate-rated-system">{{cite web
|url=http://www.bonesbearings.com/support/abec/
|title=Abec vs. Skate Rated™
|first1=George A.
|last1=Powell
|website=Bones Bearings
|url-status=live
|archive-url=https://web.archive.org/web/20141009144702/https://bonesbearings.com/support/abec/
|archive-date=2014-10-09
|access-date=2025-05-16
}}</ref>

<ref name="get-rolling-blog-engineer-perspective-on-skating">{{cite web
|url=https://getrolling.com/orbit/F08_engineer.html
|title=Inline Skates: An Engineer's Perspective
|first1=Fred
|last1=Ahrens
|date=November 2008
|website=Get Rolling - Liz Miller
|url-status=live
|archive-url=https://web.archive.org/web/20101122214818/http://getrolling.com/orbit/F08_engineer.html
|archive-date=2010-11-22
|access-date=2025-05-18
}}</ref>

<ref name="hambini-ceramic-vs-steel-bearings-friction-analysis">{{cite web
|url=https://www.hambini.com/ceramic-bearings-vs-steel-bearings-an-engineering-analysis/
|title=Ceramic Bearings vs Steel Bearings: An Engineering Analysis
|first1=Arampamoorthy
|last1=Hambinathan
|date=2020-12-11
|website=Hambini Engineering
|url-status=live
|archive-url=https://archive.today/20210507114635/https://www.hambini.com/ceramic-bearings-vs-steel-bearings-an-engineering-analysis/
|archive-date=2021-05-07
|access-date=2025-05-20
}}</ref>

<ref name="pib-factors-affecting-bearing-friction">{{cite web
|url=https://pibsales.com/tutorials/factors-affecting-friction-torque-in-bearings/
|title=Factors Affecting Friction Torque in Bearings
|first1=Kevin
|last1=Sweeney
|date=2024-02-10
|website=Pacific International Bearing
|url-status=live
|archive-url=https://web.archive.org/web/20250519024544/https://pibsales.com/tutorials/factors-affecting-friction-torque-in-bearings/
|archive-date=2025-05-19
|access-date=2025-05-20
}}</ref>

<ref name="miniature-bearings-australia-skate-bearing-faq">{{cite web
|url=http://www.minibearings.com.au/hobby/skate.html
|title=Skate Bearing FAQ
|date=2004-01-30
|website=Miniature Bearings Australia
|url-status=dead
|archive-url=https://web.archive.org/web/20050307085806/http://www.minibearings.com.au/hobby/skate.html
|archive-date=2005-03-07
|access-date=2025-05-20
}}</ref>

<ref name="bds-bearings-complete-guide-bearing-seals-types-designations">{{cite web
|url=https://www.bdsbearing.com/blog/guide-to-bearings-seals-types-functions-and-applications
|title=A Comprehensive Guide to Bearings Seals: Types, Functions, and Applications
|first1=Jeanette
|last1=Pfeifer
|website=BDS Bearings
|url-status=live
|archive-url=https://web.archive.org/web/20241114114851/https://www.bdsbearing.com/blog/guide-to-bearings-seals-types-functions-and-applications
|archive-date=2024-11-14
|access-date=2025-05-23
}}</ref>

<ref name="bds-bearings-bearing-nomenclature-guide">{{cite web
|url=https://7000765.fs1.hubspotusercontent-na1.net/hubfs/7000765/Bonus%20Content/BDS%20-%20Bearing%20Book-2024.pdf
|title=Bearing Nomenclature Guide
|date=2024
|website=BDS Bearings
|url-status=live
|archive-url=https://web.archive.org/web/20250524181144/https://7000765.fs1.hubspotusercontent-na1.net/hubfs/7000765/Bonus%20Content/BDS%20-%20Bearing%20Book-2024.pdf
|archive-date=2025-05-24
|access-date=2025-05-24
}}</ref>

<ref name="schaeffler-ina-product-reference-guide-2003">{{cite web
|url=https://www.schaeffler.com/remotemedien/media/_shared_media/08_media_library/01_publications/schaeffler_2/catalogue_1/downloads_6/prg_us_us.pdf
|title=INA/Schaeffler Product Reference Guide (732 pages)
|date=2003
|website=Schaeffler
|url-status=live
|archive-url=https://web.archive.org/web/20250524182817/https://www.schaeffler.com/remotemedien/media/_shared_media/08_media_library/01_publications/schaeffler_2/catalogue_1/downloads_6/prg_us_us.pdf
|archive-date=2025-05-24
|access-date=2025-05-24
}}</ref>

<ref name="fireball-dragon-bearings-6-misconceptions-about-bearings">{{cite web
|url=https://fireballsupply.co/blogs/news/common-misconceptions-about-skateboard-bearings
|title=6 Common Misconceptions About Skateboard Bearings
|date=2020-08-17
|website=Fireball Supply / Dragon Bearings
|url-status=live
|archive-url=https://web.archive.org/web/20250214182511/https://fireballsupply.co/blogs/news/common-misconceptions-about-skateboard-bearings
|archive-date=2025-02-14
|access-date=2025-05-23
}}</ref>

<ref name="ntn-snr-rolling-bearings-handbook-2017">{{cite web
|url=https://www.ntn-snr.com/sites/default/files/2017-03/rolling_bearings_handbook_en.pdf
|title=NTN Rolling Bearings Handbook
|date=March 2017
|website=NTN-SNR
|url-status=live
|archive-url=https://web.archive.org/web/20180918114105/https://www.ntn-snr.com/sites/default/files/2017-03/rolling_bearings_handbook_en.pdf
|archive-date=2018-09-18
|access-date=2025-05-23
}}</ref>

<ref name="vandem-longboard-on-skateboard-bearings-the-truth">{{cite web
|url=https://vandemlongboardshop.co.uk/pages/skateboard-bearings
|title=Skateboard Bearings - the Truth
|website=Vandem Longboard Shop
|url-status=live
|archive-url=https://web.archive.org/web/20200805110055/https://vandemlongboardshop.co.uk/pages/skateboard-bearings
|archive-date=2020-08-05
|access-date=2025-05-24
}}</ref>

<ref name="cryptonics-1995-patent-bearing-seat-to-eliminate-bearing-clicks">{{Cite patent
|country=US
|number=5685649
|fdate=1995-12-15
|pubdate=1997-11-11
|gdate=1997-11-11
|title=Wheel adapted to eliminate bearing click
|inventor1-first=Charles H.
|inventor1-last=Demarest
|inventor2-first=Paul C.
|inventor2-last=Jensen
|inventor3-first=Gerard F.
|inventor3-last=Lutz
|assign1=Kryptonics Inc
|assign2=Bravo Sports Corp
}}</ref>

<ref name="hook-1995-patent-two-piece-wheel-hubs">{{Cite patent
|country=US
|number=5692809
|fdate=1995-05-18
|pubdate=1997-12-02
|gdate=1997-12-02
|title=In-line skate wheels
|inventor1-first=Kenneth Wayne
|inventor1-last=Hook
}}</ref>

<ref name="gmn-bearing-usa-on-radial-ball-bearings">{{cite web
|url=https://www.gmnbt.com/products/precision-bearings/radial-ball-bearings/
|title=Radial Ball Bearings
|website=GMN Bearing USA
|url-status=live
|archive-url=https://web.archive.org/web/20250426080321/https://www.gmnbt.com/products/precision-bearings/radial-ball-bearings/
|archive-date=2025-04-26
|access-date=2025-06-06
}}</ref>

<ref name="jtekt-on-bearings-types-axial-and-radial-loads">{{cite web
|url=https://koyo.jtekt.co.jp/en/bearing-column/bearing_trivia_1st_series/bearing_trivia_1st_series_04.html
|title=What Are the Differences Between Bearings? The various types and special features of bearings
|date=2024-11-20
|website=JTEKT Corporation
|url-status=live
|archive-url=https://web.archive.org/web/20250113233140/https://koyo.jtekt.co.jp/en/bearing-column/bearing_trivia_1st_series/bearing_trivia_1st_series_04.html
|archive-date=2025-01-13
|access-date=2025-06-06
}}</ref>

<ref name="jtekt-on-bearing-selection-04-bearing-fits-n-internal-clearance">{{cite web
|url=https://koyo.jtekt.co.jp/en/bearing-column/bearing_trivia_2nd_series/bearing_trivia_2nd_series_04.html
|title=How to Select the Right Bearing (Part 4): Bearing limiting speed, running accuracy, and fits
|date=2024-11-20
|website=JTEKT Corporation
|url-status=live
|archive-url=https://web.archive.org/web/20250115213347/https://koyo.jtekt.co.jp/en/bearing-column/bearing_trivia_2nd_series/bearing_trivia_2nd_series_04.html
|archive-date=2025-01-15
|access-date=2025-06-07
}}</ref>

<ref name="jtekt-on-bearing-selection-05-bearing-preload-n-rigidity">{{cite web
|url=https://koyo.jtekt.co.jp/en/bearing-column/bearing_trivia_2nd_series/bearing_trivia_2nd_series_05.html
|title=How to Select the Right Bearing (Part 5): Bearing preload and rigidity
|date=2024-11-20
|website=JTEKT Corporation
|url-status=live
|archive-url=https://web.archive.org/web/20250607034607/https://koyo.jtekt.co.jp/en/bearing-column/bearing_trivia_2nd_series/bearing_trivia_2nd_series_05.html
|archive-date=2025-06-07
|access-date=2025-06-07
}}</ref>

<ref name="smb-bearings-on-skate-bearings">{{cite web
|url=https://www.smbbearings.com/firebrick/ckeditor/plugins/upload/Uploads/SMB300_Skate_bearings_guide_.pdf
|title=Skate Bearings - your essential guide
|date=2020
|website=SMB Bearings
|url-status=live
|archive-url=https://web.archive.org/web/20250607035546/https://www.smbbearings.com/firebrick/ckeditor/plugins/upload/Uploads/SMB300_Skate_bearings_guide_.pdf
|archive-date=2025-06-07
|access-date=2025-06-06
}}</ref>

<ref name="smb-bearings-on-bearing-internal-clearance">{{cite web
|url=https://www.smbbearings.com/technical/bearing-internal-clearance.html
|title=Ball Bearing Internal Clearance
|website=SMB Bearings
|url-status=live
|archive-url=https://web.archive.org/web/20250607235342/https://www.smbbearings.com/technical/bearing-internal-clearance.html
|archive-date=2025-06-07
|access-date=2025-06-07
}}</ref>

<ref name="nhbb-inc-on-internal-geometry-ball-bearings">{{cite web
|url=https://www.nhbb.com/knowledge-center/engineering-reference/ball-roller-bearings/internal-geometry-ball-bearings
|title=Precision Ball & Roller Bearings - Internal Geometry of Ball Bearings
|website=New Hampshire Ball Bearings, Inc.
|url-status=live
|archive-url=https://web.archive.org/web/20250608001202/https://www.nhbb.com/knowledge-center/engineering-reference/ball-roller-bearings/internal-geometry-ball-bearings
|archive-date=2025-06-08
|access-date=2025-06-07
}}</ref>

<ref name="skf-group-on-bearing-damage-and-failure-analysis">{{cite web
|url=https://cdn.skfmediahub.skf.com/api/public/0901d1968064c148/pdf_preview_medium/0901d1968064c148_pdf_preview_medium.pdf
|title=SKF: Bearing damage and failure analysis
|date=June 2017
|others=PUB BU/I3 14219/2 EN
|website=website
|url-status=live
|archive-url=https://web.archive.org/web/20250407235627/https://cdn.skfmediahub.skf.com/api/public/0901d1968064c148/pdf_preview_medium/0901d1968064c148_pdf_preview_medium.pdf
|archive-date=2025-04-07
|access-date=2025-06-08
}}</ref>

<ref name="nasa-tech-report-on-internal-clearance-and-bearing-life-radial-ball-berings">{{cite web
|url=https://ntrs.nasa.gov/api/citations/20120008398/downloads/20120008398.pdf
|title=Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller Bearings
|first1=Fred B.
|last1=Oswald
|first2=Erwin V.
|last2=Zaretsky
|first3=Joseph V.
|last3=Poplawski
|date=April 2012
|website=NTRS - NASA Technical Reports Server
|url-status=live
|archive-url=https://web.archive.org/web/20240424103922/https://ntrs.nasa.gov/api/citations/20120008398/downloads/20120008398.pdf
|archive-date=2024-04-24
|access-date=2025-06-08
}}</ref>

<ref name="axis-baart-group-on-misalignment-capacity-of-deep-groove-ball-bearings">{{cite web
|url=https://axisbearing.com/ball-bearing-misalignment-capacity/
|title=Navigating Misalignment: How Deep Groove Ball Bearings Handle the Challenge
|website=Axis - Baart Industrial Group
|date=29 July 2024
|url-status=live
|archive-url=https://web.archive.org/web/20250426052839/https://axisbearing.com/ball-bearing-misalignment-capacity/
|archive-date=2025-04-26
|access-date=2025-06-08
}}</ref>

<ref name="skf-group-bearing-preload-2021">{{cite web
|url=https://www.skf.com/binaries/pub12/Images/0901d1968065f1f4-Bearing-preload_tcm_12-299896.pdf
|title=Bearing Preload
|date=2021
|website=SKF Group
|url-status=live
|archive-url=https://web.archive.org/web/20250407132625/https://cdn.skfmediahub.skf.com/api/public/0901d1968065f1f4/pdf_preview_medium/0901d1968065f1f4_pdf_preview_medium.pdf
|archive-date=2025-04-07
|access-date=2025-05-19
}}</ref>

<ref name="powerslide-on-inline-skate-spacers-and-proper-spacer-length">{{cite AV media
|first1=Pascal
|last1=Briand
|title=Improve the roll with the WICKED spacer kit - PIT STOP
|others=Discourses inline skate spacers: too long, too short, and how to find the right length
|url=https://www.youtube.com/watch?v=-X8QhgTBj0I
|via=YouTube
|publisher=Powerslide
|language=en
|format=video
|date=2024-02-29
}}</ref>

<ref name="vegter-everything-about-bearing-spacers">{{cite web
|first1=Ivo
|last1=Vegter
|title=Everything About Bearing Spacers
|others=See video transcript on all aspects of inline skate bearing spacers, including effects of shorter and longer spaces on bearings and bearing frictions.
|url=https://www.youtube.com/watch?v=IiF1bH1VZuI
|website=thisissoul.com
|publisher=This is Soul
|language=en
|format=video
|date=2022-02-13
}}</ref>

<ref name="stoked-ride-shop-on-bearing-spacers-skateboards">{{cite web
|url=https://stokedrideshop.com/blogs/stoked-school/why-bearing-spacers-really-matter
|title=Why Bearing Spacers Really Matter (skateboards)
|first1=David
|last1=Rajewski
|date=2015-06-01
|website=Stoked Ride Shop
|url-status=live
|archive-url=https://web.archive.org/web/20250621041430/https://stokedrideshop.com/blogs/stoked-school/why-bearing-spacers-really-matter
|archive-date=2025-06-21
|access-date=2025-06-20
}}</ref>

<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel">{{cite web
|url=https://www.rollerenligne.com/materiel/physics-of-the-inline-skate-wheel/
|title=Physics of the inline skate wheel
|website=Le Roller en Ligne
|url-status=dead
|archive-url=https://web.archive.org/web/20250322134824/https://www.rollerenligne.com/materiel/physics-of-the-inline-skate-wheel/
|archive-date=2025-03-22
|access-date=2025-03-27
}}</ref>

<ref name="mark-kempton-nottinghamskaters-on-wheel-setups">{{cite web
|url=http://www.nottinghamskaters.com/forum/viewtopic.php?p=879#879
|title=Inline Wheel Setups: A Beginners' Guide - By MarKK
|first1=Mark
|last1=Kempton
|date=2007-01-24
|website=Nottingham Skaters
|url-status=dead
|archive-url=https://web.archive.org/web/20070928201336/http://www.nottinghamskaters.com/forum/viewtopic.php?p=879#879
|archive-date=2007-09-28
|access-date=2025-06-26
}}</ref>

<ref name="madison-rec-hockey-on-hi-lo-in-hockey-skates-vs-flat-setup">{{cite web
|url=https://www.madisonrechockey.com/news/roller-hockey-chassis-hi-lo-system-vs-straight-whe
|title=Roller Hockey Chassis: Hi-lo system vs. straight wheel system
|first1=Kris
|last1=Weaver
|date=2025-03-30
|website=Madison Rec Hockey
|url-status=live
|archive-url=https://web.archive.org/web/20250628182553/https://www.madisonrechockey.com/news/roller-hockey-chassis-hi-lo-system-vs-straight-whe
|archive-date=2025-06-28
|access-date=2025-06-28
}}</ref>

<ref name="nn-skates-faqs-v-vm-rocker-165mm-trinity-ufs">{{cite web
|url=https://nnskates.com/faq/
|title=NN Skates - FAQs
|website=NN Skates
|url-status=live
|archive-url=https://web.archive.org/web/20250629214045/https://nnskates.com/faq/
|archive-date=2025-06-29
|access-date=2025-06-29
}}</ref>

<ref name="back-to-blading-history-of-50-50-freestyle-frame-juice-blocks">{{cite AV media
|url=https://www.youtube.com/watch?v=GzN-PZoZsg0
|first1=Lawrence
|last1=Ingraham
|title=What's the history of 50/50? What's the future? // Aggressive Inline Skating
|date=2018-11-16
|via=YouTube
|publisher=Publisher
|language=en
|format=video
}} See video transcript for info on freestyle frame, juice blocks, Balance Frame, etc.
</ref>

<ref name="Engineer-skates-no02">{{cite book
|url=https://books.google.com/books?id=wlFHAQAAMAAJ&pg=PA102
|title=The Engineer
|volume=41
|date=1876-02-11
|article=Historical Notes on Roller Skates No. 2
|pages=102–103
|location=London
|publisher=Morgan-Grampian
|access-date=2024-11-30
}}</ref>

<ref name="Engineer-skates-no03">{{cite book
|url=https://books.google.com/books?id=wlFHAQAAMAAJ&pg=PA121
|title=The Engineer
|volume=41
|date=1876-02-18
|article=Historical Notes on Roller Skates No. 3
|pages=121–122
|location=London
|publisher=Morgan-Grampian
|access-date=2024-11-30
}}</ref>

<ref name="Gordon-Ware-patent-US3287023A">{{Cite patent
|country=US
|number=3287023
|fdate=1964-07-16
|pubdate=1966-11-22
|gdate=1966-11-22
|title=Roller skate
|inventor1-first=Gordon K
|inventor1-last=Ware
}}</ref>

<ref name="maury-silver-tandem-skate-1975">{{Cite patent
|country=US
|number=3880441
|fdate=1973-11-08
|pubdate=1975-04-29
|gdate=1975-04-29
|title=Tandem roller hockey skate
|inventor1-first=Morris L
|inventor1-last=Silver
}}</ref>

<ref name="washingtonpost-reinvention-of-wheel-2004">{{cite news
|author=<!--not stated-->
|date=2004-08-17
|title=A Reinvention Of the Wheel
|url=https://www.washingtonpost.com/wp-dyn/articles/A6502-2004Aug16.html
|url-status=live
|newspaper=Washington Post
|first=Eric M.
|last=Weiss
|location=Washington DC
|archive-url=https://web.archive.org/web/20070808201310/https://www.washingtonpost.com/wp-dyn/articles/A6502-2004Aug16.html
|archive-date=2007-08-08
|access-date=2024-12-20
}}</ref>

<ref name="MIA-olson-inventive-impulse">{{cite web
|url=https://new.artsmia.org/stories/mind-in-motion-the-mias-leonardo-show-traces-scott-olsons-inventive-impulse/
|title=Mind in motion: The MIA's Leonardo show traces Scott Olson's inventive impulse
|website=Minneapolis Institute of Art
|url-status=live
|archive-url=https://web.archive.org/web/20240227015018/https://new.artsmia.org/stories/mind-in-motion-the-mias-leonardo-show-traces-scott-olsons-inventive-impulse/
|archive-date=2024-02-27
}}</ref>

<ref name="VMH-history-with-pic-gallery">{{cite web
|url=https://history.vintagemnhockey.com/page/show/1136093-minnesota-in-line-hockey-and-history-of-in-line-skates
|title=Minnesota In-Line Hockey and History of In-Line Skates
|website=Vintage Minnesota Hockey
|url-status=live
|archive-url=https://web.archive.org/web/20240715001103/https://history.vintagemnhockey.com/page/show/1136093-minnesota-in-line-hockey-and-history-of-in-line-skates
|archive-date=2024-07-15
|access-date=2024-12-26
}} A picture gallery at the bottom of the page shows rare historical images of early Rollerblade prototypes and products including the Ultimate Street Skate.
</ref>

<ref name="usenet-chen-FAQ-inline-origin">{{cite newsgroup
 | title = Q: What are the origins of in-line skates?
 | author = Anthony D. Chen
 | date = 1993-11-04
 | newsgroup = rec.skate
 | url = https://groups.google.com/g/rec.skate/c/wJL3ruYbEYk
 | access-date = 2024-12-23
 | archive-url = https://web.archive.org/web/20241223202232/https://groups.google.com/g/rec.skate/c/wJL3ruYbEYk
 | archive-date = 2024-12-23
}}</ref>

<ref name="rollerblade-dk-superguides-inline-skating-2000">{{cite book
|url=https://books.google.com/books?id=Kf_ZTqDa9YUC
|title=Superguides: Inline Skating
|location=London
|publisher=DK Pub
|year=2000
|isbn=0789465426
|access-date=2024-12-29
|first1=Dawn
|last1=Irwin
|quote=A picture of 1981 Ultimate Hockey Skate is shown under the headline: Modern inline skate
|quote-page=11
}}</ref>

<ref name="bernstein-minnesota-hockey-inline">{{cite book
|chapter-url=https://archive.org/details/morefrozenmemori0000ross/page/184/mode/1up?view=theater
|title=More... Frozen Memories: Celebrating a Century of Minnesota Hockey
|chapter=In-Line Hockey In Minnesota
|pages=184–185
|location=Minneapolis, Minn.
|publisher=Nodin Press
|year=2007
|isbn=978-1932472493
|access-date=2024-12-24
|first1=Ross
|last1=Bernstein
}}</ref>

<ref name="brennan-olson-1987-patent-modern-inline-skates">{{Cite patent
|country=US
|number=4909523
|fdate=1987-06-12
|pubdate=1990-03-20
|gdate=1990-03-20
|title=In-line roller skate with frame
|inventor1-first=Brennan J.
|inventor1-last=Olson
|assign1=Rollerblade Inc
}}</ref>

<ref name="inlineskates-types-of-skates">{{cite web
|url=https://www.inlineskates.com/Types-of-Inline-Skates/article-4-8-2010,default,pg.html
|title=Types of Inline Skates
|website=Inline Skates
|url-status=dead
|archive-url=https://web.archive.org/web/20181017082153/https://www.inlineskates.com/Types-of-Inline-Skates/article-4-8-2010,default,pg.html
|archive-date=2018-10-17
|access-date=2025-01-06
}}</ref>

<ref name="bladeville-components-of-aggressive-skates">{{cite web
|url=https://bladeville.com/blog/how-aggressive-inline-skates-are-built
|title=How aggressive inline skates are built
|website=Bladeville
|url-status=live
|archive-url=https://archive.today/20250112023306/https://bladeville.com/blog/how-aggressive-inline-skates-are-built
|archive-date=2025-01-12
|access-date=2025-01-12
}}</ref>

<ref name="x-games-history-official-page">{{cite web
|url=https://www.xgames.com/our-history
|title=Our X Games History
|website=X Games
|url-status=live
|archive-url=https://web.archive.org/web/20250215135205/https://www.xgames.com/our-history
|archive-date=2025-02-15
|access-date=2025-02-20
}}</ref>

<ref name="skatepro-all-aspects-of-speed-skates">{{cite web
|url=https://www.skatepro.com/en-us/a12.htm
|title=Buying Speed Skates
|website=SkatePro
|url-status=live
|archive-url=https://web.archive.org/web/20250125035753/https://www.skatepro.com/en-us/a12.htm
|archive-date=2025-01-25
|access-date=2025-01-25
}}</ref>

<ref name="bladeville-wizard-frames-and-rest">{{cite web
|url=https://bladeville.com/blog/how-rockering-in-wizard-like-inline-skate-frames-work
|title=Rockering in Wizard Frames & Rest of the Pack
|website=Bladeville
|url-status=live
|archive-url=https://web.archive.org/web/20250205031900/https://bladeville.com/blog/how-rockering-in-wizard-like-inline-skate-frames-work
|archive-date=2025-02-05
|access-date=2025-02-05
}}</ref>

<ref name="endlessblading-86-frame-spec-comparison">{{cite web
|url=https://help.endlessblading.com/article/86-frame-spec-comparison
|title=Endless Frame Spec Comparison & Overview
|website=Endless Blading
|url-status=live
|archive-url=https://web.archive.org/web/20250216043024/https://help.endlessblading.com/article/86-frame-spec-comparison
|archive-date=2025-02-16
|access-date=2025-02-16
}}</ref>

<ref name="endlessblading-geometry-of-inline-rocker-designs">{{cite web
|url=https://www.endlessblading.com/blogs/news/the-geometry-of-inline-skate-rocker-designs
|title=The Geometry of Inline Skate Rocker Designs
|website=Endless Blading
|date=11 July 2020
|url-status=live
|archive-url=https://web.archive.org/web/20250216043322/https://www.endlessblading.com/blogs/news/the-geometry-of-inline-skate-rocker-designs
|archive-date=2025-02-16
|access-date=2025-02-16
}}</ref>

<ref name="endlessblading-balanced-rocker-on-4x90mm-trinity-frame">{{cite web
|url=https://help.endlessblading.com/article/33-balanced-rocker
|title=Balanced Rocker
|website=Endless Blading
|url-status=live
|archive-url=https://web.archive.org/web/20250626015019/https://help.endlessblading.com/article/33-balanced-rocker
|archive-date=2025-06-26
|access-date=2025-06-26
}} Balanced rocker setup with 4x90mm wheels on the Endless Trinity 90 frame.
</ref>

<ref name="rockin-frames-on-MIX4-and-165mm-mid-wheel-reductions">{{cite web
|url=https://rockinframes.com/lets-talk-facts-rockin-mix4-100-90/
|title=Let's talk facts: ROCKIN' MIX4 100/90
|date=2022-02-10
|website=ROCKIN’ Frames
|url-status=live
|archive-url=https://web.archive.org/web/20250302165315/https://rockinframes.com/lets-talk-facts-rockin-mix4-100-90/
|archive-date=2025-03-02
|access-date=2025-03-02
}}</ref>

<ref name="ricardo-lino-on-trinity-2017">{{cite AV media
|url=https://www.youtube.com/watch?v=K5lwwHnCLSA
|first1=Ricardo
|last1=Lino
|title=Why Trinity? The latest generation inline skates frame system // vlog 182
|date=2017-11-07
|via=YouTube
|language=en
|format=video
}} See video transcript.
</ref>

<ref name="gallaghercorp-polyurethane-resilience-elasticity-rebound">{{cite web
|url=https://gallaghercorp.com/white-papers-polyurethane-resilience/
|title=Polyurethane-Resilience
|website=Gallagher Corporation
|url-status=live
|archive-url=https://web.archive.org/web/20240803071827/https://gallaghercorp.com/white-papers-polyurethane-resilience/
|archive-date=2024-08-03
|access-date=2025-03-08
}}</ref>

<ref name="hirschmugl-august-skate-wheel-plastic-hub-patent-1954">{{Cite patent
|country=US
|number=2697010
|fdate=1951-07-13
|pubdate=1954-12-14
|gdate=1954-12-14
|title=Roller skate wheel
|inventor1-first=Hirschmugl Robert
|inventor1-last=August
}}</ref>

<ref name="usenet-chen-FAQ-inline-wheels">{{cite newsgroup
 | title = Skate FAQs: Wheels and Hop-up Kits
 | author = Anthony D. Chen
 | date = 1992-05-17
 | newsgroup = rec.skate
 | url = http://skatefaq.adchen.com/wheels.html
 | url-status=live
 | access-date = 2025-03-29
 | archive-url = https://archive.today/20250329231124/http://skatefaq.adchen.com/wheels.html
 | archive-date = 2025-03-29
}}</ref>

<ref name="powerslide-download-guides-wheels">{{cite web
|url=https://powerslide.com/cdn/shop/files/PS_WHEELS_INFOGRAPHICS_final.pdf
|title=Powerslide Wheels Guide
|website=Powerslide
|url-status=live
|archive-url=https://web.archive.org/web/20240531222450/https://powerslide.com/cdn/shop/files/PS_WHEELS_INFOGRAPHICS_final.pdf
|archive-date=2024-05-31
|access-date=2025-03-22
}}</ref>

<ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997">{{Cite patent
|country=US
|number=5922151
|fdate=1997-07-11
|pubdate=1999-07-13
|gdate=1999-07-13
|title=Polyurethane skate wheel with shaped foam core
|inventor1-first=Neal
|inventor1-last=Piper
|inventor2-first=Tom
|inventor2-last=Peterson
|assign1=Hyper Corp (Hyper Wheels)
}}</ref>

<ref name="markus-thierstein-wheel-rotation">{{cite web
|url=https://skating.thierstein.net/Knowledge/Inline_Skating_Rollerblading_Information_Wheel_rotation.html
|title=Inline Skating Knowledge: Rotating Wheels
|first1=Markus
|last1=Thierstein
|website=Skating Thierstein
|url-status=live
|archive-url=https://web.archive.org/web/20250228235646/https://skating.thierstein.net/Knowledge/Inline_Skating_Rollerblading_Information_Wheel_rotation.html
|archive-date=2025-02-28
|access-date=2025-04-29
}}</ref>

<ref name="us-patent-6309108-bearing-spacer-bearing-assembly">{{Cite patent
|country=US
|number=6309108
|fdate=1997-07-11
|pubdate=2001-10-30
|gdate=2001-10-30
|title=Bearing spacer for in-line skate
|inventor1-first=Richard
|inventor1-last=Wershe
}}</ref>

<ref name="wizard-skating-product-NR-frames-NR90">{{cite web
|url=https://wizardskating.com/products/wizard-nr-frames
|title=Wizard NR Frames (showing NR90)
|website=Wizard Skating
|url-status=live
|archive-url=https://web.archive.org/web/20250418222939/https://wizardskating.com/products/wizard-nr-frames
|archive-date=2025-04-18
|access-date=2025-05-28
}}</ref>

<ref name="gorski-skate-o-pedia-aggressive-skates">{{cite web
|url=http://www.inlineskates.com/Aggressive-Skates/article-3-27-2010%2Cdefault%2Cpg.html
|title=Skate-O-Pedia / Articles / Aggressive Skates
|first1=Chris
|last1=Gorski
|website=Inlineskates.com
|url-status=dead
|archive-url=https://web.archive.org/web/20211018234026/http://www.inlineskates.com/Aggressive-Skates/article-3-27-2010%2Cdefault%2Cpg.html
|archive-date=2021-10-18
|access-date=2025-02-09
}}</ref>

<ref name="liveabout-carlesa-williams-wheels-101">{{cite web
|url=https://www.liveabout.com/inline-skate-wheels-4122926
|first1=Carlesa
|last1=Williams
|title=Inline Skate Wheels 101
|date=2017-10-25
|website=LiveAbout
|url-status=live
|archive-url=https://web.archive.org/web/20250404024354/https://www.liveabout.com/inline-skate-wheels-4122926
|archive-date=2025-04-04
|access-date=2025-04-04
}}</ref>

<ref name="hamilton-rolling-resistance-and-wheels">{{cite web
|url=https://www.hamiltoncaster.com/Portals/0/blog/White%20Paper%20Rolling%20Resistance.pdf
|title=Rolling Resistance and Industrial Wheels
|date=2013-02-01
|website=Hamilton Caster & Mfg. Co.
|url-status=live
|archive-url=https://web.archive.org/web/20250421030719/https://www.hamiltoncaster.com/Portals/0/blog/White%20Paper%20Rolling%20Resistance.pdf
|archive-date=2025-04-21
|access-date=2025-04-21
}}</ref>

<ref name="chomin-harry-patent-US1527840">{{Cite patent
|country=US
|number=1527840
|fdate=1924-05-08
|pubdate=1925-02-24
|gdate=1925-02-24
|title=Skate
|inventor1-first=Chomin
|inventor1-last=Harry
}}</ref>

<ref name="siffert-christian-patent-US2113862">{{Cite patent
|country=US
|number=2113862
|fdate=1936-04-27
|pubdate=1938-04-12
|gdate=1938-04-12
|title=Roller skate
|inventor1-first=Siffert
|inventor1-last=Christian
}}</ref>

<ref name="runrepeat-heel-to-toe-drop">{{cite web
|url=https://runrepeat.com/guides/heel-to-toe-drop
|title=Heel to Toe Drop: The Ultimate Guide
|website=RunRepeat
|url-status=live
|archive-url=https://web.archive.org/web/20250205033231/https://runrepeat.com/guides/heel-to-toe-drop
|archive-date=2025-02-05
|access-date=2025-02-05
}}</ref>

<ref name="oxford_dictionary_word_rollderblade_as_brand_and_verb">{{cite book
|url=https://archive.org/details/oxfordenglishdic0000unse_s1d3/page/339/mode/1up
|title=Oxford English Dictionary: Additions Series
|volume=3
|page=339
|publisher=Oxford University Press
|location=Oxford
|year=1997
|access-date=2025-01-08
|editor-first1=Michael
|editor-last1=Proffitt
}}</ref>

}}

==External links==
{{Commons category|Inline skates}}

* [https://www.rollerskatingmuseum.org/ The National Museum of Roller Skating] - many historical roller and inline skates mentioned in this article are featured in this museum's collections.
* [https://web.archive.org/web/20241127024010/http://www.faqs.org/faqs/sports/skating/books/part1/ Skating Book FAQ / Bibliography, part 1 of 2] - a listing of inline skating books published in the heyday of inline skating, in the 1990s. Part 1 includes books on inline skating, roller hockey, and quad skating. TOC from each book is reproduced, along with a short summary of the book.

{{Inline skating}}
{{Human-powered vehicles}}
{{footwear}}
{{Authority control}}

{{DEFAULTSORT:Inline Skates}}
[[Category:Inline skates]]
[[Category:Inline skating]]
[[Category:Roller skates]]
[[Category:Roller skating equipment]]
[[Category:Sports footwear]]
[[Category:Wheeled vehicles]]
[[Category:1980s fads and trends]]
[[Category:1990s fads and trends]]