Editing Inline skates (section)

=== Wheel rebound ===

[[File:Playing inline hockey on a parking lot-IMG 9273-FRD.jpg|thumb|right|260px|Rebound improves cornering]]

'''Wheel rebound''' refers to the amount of energy a polyurethane wheel returns as it recovers its shape after being deformed by weight or force. While the term is commonly used, there is no consensus on how to consistently measure and publish rebound ratings. However, the relative rebound of different wheels can be easily compared by dropping them from the same height and observing how high each one bounces back from the floor.<ref name="powell-svensson-inline-skating"/>{{rp|24–26}}<ref name="joyner-inline-hockey-1995"/>{{rp|21–22}}

Rebound is a universally-desirable trait, unlike other wheel characteristics that must be carefully chosen to suit a skater’s style, terrain, and preferences. Across all disciplines and surfaces, the higher the rebound, the better. Such is not true of diameter, profile, or hardness. If cost were no concern, skaters would always choose the wheels with the highest rebound.<ref name="bladeville-hardness-of-inline-skate-wheels"/>

[[File:Foco Roberta in azione durante una run di Skate Slalom.jpg|thumb|right|260px|High rebound feels alive]]

A '''high-rebound''' wheel feels lively, snappy, and responsive, while a low-rebound wheel feels dead. Skaters on high-rebound wheels roll faster and with less effort, as more of the energy generated by each push against the ground is returned by the wheels and converted into forward motion. In contrast, '''low-rebound''' wheels behave more like flat tires; they absorb energy rather than returning it, forcing the skater to work harder to maintain speed, much like walking on soft sand.<ref name="gallaghercorp-polyurethane-resilience-elasticity-rebound"/><ref name="inline-warehouse-wheel-buying-guide"/>

A polyurethane compound can be formulated to exhibit a wide range of rebound characteristics, independent of its hardness. These are distinct properties of a polyurethane wheel. '''Hardness''' determines how much the wheel deforms under load, such as the compression caused by a skater’s weight. '''Rebound''' refers to how much of that deformation energy is returned to help propel the skater forward.{{efn-ua|name=gallaghercorp-rebound-is-not-hardness}}<ref name="le-roller-en-ligne-on-physics-of-inline-skate-wheel"/><ref name="powell-svensson-inline-skating"/>{{rp|24–26}}

[[Image:Elastic Hysteresis.svg|thumb|right|Elastic hysteresis graph: energy dissipated and not returned by rebound shown as center area]]

Rebound can be measured in several ways, including the [[Bayshore Resilience]] test and the Rebound Resilience test. The former calculates the ratio of rebound height to drop height, while the latter measures the percentage of energy returned after an impact. When applied to polyurethane, these tests are often described collectively as measuring '''polyurethane resilience''', an industry term synonymous with rebound. Although both tests aim to quantify a material’s [[Elasticity (physics)|elasticity]], their results are not directly comparable or convertible. In the context of inline skate wheels, rebound is rarely specified in technical datasheets. When it is, it’s typically presented using vague, consumer-friendly labels such as High Rebound (HR), Super High Rebound (SHR), or Ultra High Rebound (UHR).<ref name="gallaghercorp-polyurethane-resilience-elasticity-rebound"/><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="bladeville-hardness-of-inline-skate-wheels"/><ref name="powerslide-download-guides-wheels"/>

In mechanics, rebound is often characterized by its complementary property, [[Hysteresis#Elastic hysteresis|elastic hysteresis]]. Rebound refers to the amount of energy a wheel returns after deformation. On the other hand, elastic hysteresis measures the amount of energy lost, typically as heat, during the deformation and recovery cycle. These two properties are inversely proportional: a wheel with high elastic hysteresis dissipates more energy as heat when compressed and released, resulting in 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><ref name="gallaghercorp-polyurethane-resilience-elasticity-rebound"/>