Bicycle wheel metal or carbon fiber rim which holds a pneumatic rubber tire. A hub is the center part of a bicycle wheel. It consists of an axle, bearings and a hub shell. The hub shell typically has two machined metal flanges to which spokes can be attached. Hub shells can be one-piece with press-in cartridge or free bearings or, in the case of older designs, the flanges may be affixed to a separate hub shell. The axle is attached to dropouts on the fork or the frame. The axle can attach using a: Modern bicycles have adopted standard axle spacing: the
Wheel hub motor designs have minimized the electrical steel content of the motor by using a coreless design with Litz wire coil windings to reduce eddy current losses. This significantly reduces wheel motor weight and therefore unsprung weight. Another method used is to replace the cast iron friction brake assembly with a wheel motor assembly of similar weight. This results in no net gain in unsprung weight and provides a car capable of braking up to 1G. A good example of this is the Michelin Active Wheel motor as fitted to the Heuliez Will, the first electric car with an Active Wheel drive,