Editing Inline skates (section)

=== How bearings work ===

{{multiple image
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 | total_width = 300
 | image1 = Rollerblade 303 70mm 85A hubless inline skate wheels by Kryptonics ca 1980s-608ZZ TMK bearings-IMG 6757-bg-FRD.png
 | caption1 = From the 1980s
 | image2 = Ball Bearing with Semi Transparent Cover.JPG
 | caption2 = ISO 608 bearing
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[[Ball bearing]]s enable inline skate wheels to rotate freely and smoothly. The adoption of modern ISO 608 ball bearings, combined with polyurethane wheels, helped propel inline skating to peak popularity in the 1990s.<ref name="usenet-chen-FAQ-inline-bearings"/><ref name="bernstein-minnesota-hockey-inline"/><ref name="vegter-names-in-inline-skating"/>

{{multiple image
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 | footer = Bearings separate a wheel from the rest of the skate
 | image1 = Brennan J Olson-US4909523A-1990-Inline roller skate-Patent Drawing-FIG 2-bearing assembly and hub-prior art.png
 | image2 = Anatomy of Frame Wheel n Axle Assemblies in Inline Skates with labels n transfixed parts.svg
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Ball bearings separate the skate’s only moving parts, the wheels, from the non-moving structure. Wheels rotate around axles, which are bolted tightly to the frame. The frame is, in turns, firmly attached to the boot. Thus all non-moving parts of the skate remain fixed in place, securely connected using glue, rivets, welds, bolts, or other fastening methods. Bearings minimize friction between the wheel and the axle, allowing skaters to reach higher speeds 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"/>
}}

{{multiple image
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 | footer = Bearing balls separate outer race from inner race
 | image1 = Rolling-element bearing (numbered).png
 | image2 = Bearing Preloading in inline skate wheel assembly-with labels.svg
 | image_gap = 10
}}

Bearings are precision-made to endure high-speed rotations. On flat terrain, a skater on 80mm wheels can cruise at a speed of 20 km/h (12.4 mph). At that speed, the wheels, and thus the bearings, rotate at 1,326 revolutions per minute (RPM). To withstand the heat and stress of such speeds, bearings are typically made from durable materials like stainless steel, chrome steel, or ceramic.<ref name="usenet-chen-FAQ-abec-hype"/><ref name="us-patent-6309108-bearing-spacer-bearing-assembly"/><ref name="powerslide-download-guides-bearings-by-wicked"/>

A ball bearing consists of two concentric rings: an outer race and an inner race, separated by a set of rolling balls, usually between 5 and 8 in an ISO 608 bearing. The outer race is fixed to the wheel hub and rotates with it, while the inner race is fixed to the axle and remains stationary. Deep grooves are machined into the races to form raceways that securely hold the balls in place. A retainer, or cage, separates the balls and distributes them evenly 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"/>