Editing Inline skates (section)

=== Rolling resistance ===

[[File:Roller speed skating at the 2018 Summer Youth Olympics – Boys Quarterfinals Run 4 66-zommed in.jpg|thumb|right|300px|Gliding with minimum rolling resistance]]

[[Rolling resistance]] is often the main factor limiting a skater’s ability to reach top speed. Also known as '''rolling friction''' or '''rolling drag''', it refers to the force that opposes the rolling motion of the wheels as the skater glides across a surface.<ref name="publow-speed-skating-1999"/><ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/>

Several factors influence rolling resistance, but the most significant is typically [[elastic hysteresis]]. Recognizing its impact, all reputable wheel manufacturers formulate polyurethane compounds to deliver high '''rebound''' and thus low elastic hysteresis. This is particularly crucial in speed skating, where maximizing top speed is the primary objective.<ref name="outside-online-tire-rolling-resistance-bikes"/><ref name="naomi-grigg-2014"/>{{rp|18–19}}<ref name="publow-speed-skating-1999"/>{{rp|316}}

[[File:Footprint of an inline skate wheel showing a deformed profile from weight of a skater-FRD.svg|thumb|right|160px|Wheel footprints]]

The '''weight''' of the skater and the '''hardness''' of the wheel together determine the degree of wheel '''deformation''' and the resulting increase in '''footprint''' under load. Footprint is another key contributor to rolling resistance. In general, speed skaters favor hard wheels with a pointy profile, which create smaller footprints and therefore minimize rolling resistance when skated upright. The desire to reduce gliding footprint while maintaining comfort led to the development of dual-density wheels.<ref name="us-patent-5922151-hyper-wheels-dual-density-pu-1997"/><ref name="publow-speed-skating-1999"/>{{rp|316}}

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

The '''roughness''' of the terrain is another key contributor to rolling resistance. As a wheel rolls over a bumpy surface, energy is lost in repeatedly lifting the skater’s weight over each small imperfection. The need to cushion bumpy rides without increasing the wheel’s footprint under load was a major driving force behind the development of dual-density wheels.<ref name="hamilton-rolling-resistance-and-wheels"/><ref name="outside-online-tire-rolling-resistance-bikes"/><ref name="us-patent-6227622-k2-dual-density-pu-1997"/><ref name="cross-surface-roughness-on-rolling-resistance"/>

Wheel '''diameter''' is another important factor in rolling resistance, particularly on rough terrain. In general, larger wheels roll more easily over uneven surfaces. Increasing wheel diameter reduces the coefficient of rolling resistance by decreasing the angle of incidence between the wheel perimeter and surface imperfections. In other words, a larger wheel can bridge bumps and irregularities more smoothly, resulting in less energy loss and easier rolling. This is why relatively large wheels, typically ranging from 90 mm to 125 mm, are commonly used in urban skating and marathon skating, where both speed and the ability to handle imperfect surfaces are essential.<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_Effects_of_surface_roughness_on_rolling_friction
| 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
}}</ref><ref name="hamilton-rolling-resistance-and-wheels"/><ref name="welch-demystify-inline-disciplines"/>