Editing Inline skates (section)

=== Contamination and bearing friction ===

[[File:Inline bearings-Bauer ZZ metal gap shield-Non removable-Disassembled-IMG 7668-FRD.jpg|thumb|right|300px|Disasembled ZZ gap shields]]

In addition to the rolling resistance generated by the wheels, skaters also experience energy loss due to '''bearing friction'''. As the outer race of a bearing rotates around the inner race, various internal components - such as the balls, cage, lubricant, raceways, and seals - dissipate energy through rolling friction, sliding contact, and viscous drag. Bearing friction encompasses all of these sources of energy loss.<ref name="hambini-ceramic-vs-steel-bearings-friction-analysis"/><ref name="pib-factors-affecting-bearing-friction"/>

In practice, however, bearing friction in clean, properly lubricated bearings is insignificant compared to the rolling resistance of polyurethane wheels. Purpose-built bearings from reputable brands usually meet or exceed ABEC 3 specifications. As a result, bearing selection has a comparatively small impact on overall performance for the majority of inline skaters, while bearings are still new and clean.<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}}

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Bearing selection, however, plays a significant role in determining how long bearings perform efficiently and reliably as advertised, before requiring cleaning or replacement. This largely depends on the bearing’s ability to resist contamination from dirt, dust, and moisture. Even microscopic debris, such as particles the size of a human hair, can scratch raceways and interfere with smooth rotation. Among all factors affecting bearing performance, '''contamination''' is considered the most detrimental. It can significantly reduce efficiency, slow rotation, or in severe cases, cause the bearing to seize. Under such conditions, any theoretical performance advantages based on manufacturer specifications become irrelevant.<ref name="miniature-bearings-australia-skate-bearing-faq"/><ref name="bones-bearings-maintaining-your-bones-bearings"/> Skaters often joke that 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"/>