TRANSMISSION UNIT FOR A BICYCLE

摘要

A transmission unit 1 comprises a shaft 9 which is connected to a frame of a bicycle, as well as a wheel hub 11 rotatable around the shaft and in which spokes 13 of the wheel are mounted. The transmission unit 1 further includes a transmission 15 having an input 19 and an output 21 which are concentric to the wheel hub 11. The output 21 is coupled to the wheel hub 11 via a planetary gear set 25. The transmission unit 1 further includes an electromotor 33 having a stator 35 which is connected to the shaft 9 and a rotor 37 which is connected to the input 19 of the transmission. The stator 35 and the rotor 37 of the electromotor 33 are concentric to the wheel hub 11. During the switching of the transmission 15 the electromotor 33 produces a counter torque that is opposed to the drive torque applied to the input 19 by the drive source (cyclist). The transmission 15 is an automatic transmission which switches between the transmission ratios in dependence on the rpm and/or the drive torque on the input 19.