Bicycle wheel the hub or the bike. Since the rim must be centered, but the hub flanges are not, there is a difference in dish between the two sides. Such an asymmetrical wheel is called a "dished" wheel. The side of the wheel with less dish has slightly shorter but significantly higher-tensioned spokes than the side with more dish. Several different techniques have been tried to minimize this spoke asymmetry. In addition to modified hub geometry, some rims have off-center spoke holes, and the mounting of common J-bend spokes at the hub flange can be altered "inboard" or "outboard". A truing stand
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