Abstract: A power supply and transmission system for a bicycle of the type having a frame and a crank housing for a crank-and-pedal and from said crank housing a projecting fork carrying the drive wheel over the drive hub at the other end thereof, and in which the power transmission system comprises a drive shaft which at both ends is connected to angle gears at the crank housing and the drive hub and in which the drive shaft is enclosed in one of the fork tubes, and the power supply is directly connected to the power transmission system at the drive wheel hub. Preferably the crank housing is formed with a several stage gear. The drive wheel hub is formed as a free wheel hub which when pedaling the bicycle forwardly provides a power transmission between the drive shaft and the outer sleeve of the hub.