Patent ID: 7370720

Claim:
An electromotive power assisted bicycle, comprising: a drive shaft to be rotated by a pedal effort; a primary sprocket fixed to said drive shaft for transmitting said pedal effort to a drive wheel; a secondary sprocket fixed to said drive shaft coaxially with said primary sprocket; a pedal effort detection means for detecting the pedal effort; an electromotive power output unit box detachably mounted to a body of the bicycle for outputting an electromotive power in response to the pedal effort detected by said pedal effort detection means; a power sprocket coupled to a rotating output shaft of said electromotive power output unit box; an auxiliary chain stretched across between said secondary sprocket and said power sprocket; a supporting section for rotatably supporting said drive shaft; and a unit mounting bracket on which said electromotive power output unit box is mounted, said unit mounting bracket being fixed to said supporting section with the drive shaft penetrating through said unit mounting bracket.