To rationally and properly arrange a transmission mechanism of driving force to a driving shaft in a bicycle.

This bicycle has the driving shaft 8 of a driving wheel 2a rotatably supported on a frame rear part 6, an input side rotor 9 provided with first free gear 9a linked with a pedal body 3 and a first sprocket 9b, a speed change rotor 10 provided with a transmission 10a having input part and output part, a second sprocket 10b provided in the input part of the transmission 10a and linked with the first sprocket 9b of the input side rotor 9, and a third sprocket 10c provided in the output part of the transmission 10a and supported on the frame rear part 6, and a fourth sprocket 8c provided in the driving shaft 8 and linked with the third sprocket 10c of the speed change rotor 10. The input side rotor 9 is provided in the driving shaft 8 to be rotatable with the driving shaft 8 as a center.

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