Motorcycle wheel wheels are predominantly made from an aluminium-alloy, but can also be made from more-exotic materials, such as magnesium content alloy or carbon fibre. The first commercial motorcycles were built like bicycles, with wire wheels as bicycles had traditionally been fitted with. The Steffey motorcycle in 1902, essentially a bicycle with a two-stroke engine attached, used wooden rims with wire spokes. This style of wheel evolved into a stouter motorcycle-specific wheel, still with spokes, up to the 1960s and beyond. In April, 1922, Borrani started production of motorcycle wheels with an aluminium rim. Although cast wheels had already been used on
Bicycle wheel hubs of front wheels are generally 100 mm wide fork spacing, road wheels with freehubs generally have a 130 mm wide rear wheel hub. Mountain bikes have adopted a 135 mm rear hub width, which allows clearance to mount a brake disc on the hub or to decrease the wheel dish for a more durable wheel. Freeride and downhill are available with both 142 and 150 mm spacing. The bearings allow the hub shell (and the rest of the wheel parts) to rotate freely about the axle. Most bicycle hubs use steel or ceramic ball bearings. Some hubs use serviceable