ELECTRICALLY POWERED ASSIST BICYCLE

摘要

An electromotive power assisted bicycle comprises a drive shaft 4 to be rotated by a pedal effort; a primary sprocket 2 fixed to the drive shaft 4 for transmitting the pedal effort to a drive wheel 22; a secondary sprocket fixed to the drive shaft 4 coaxially with the primary sprocket 2; a pedal effort detection sensor for detecting a pedal effort; an electromotive power output unit box 13 detachably attached to the body for outputting an electromotive power in response to the pedal effort detected by the pedal effort detection sensor; a power sprocket coupled to a rotating output shaft of the electromotive power output unit box 13; an auxiliary chain stretched across between the secondary sprocket and the power sprocket; and a battery bracket 165 capable of accommodating a battery 162 for the electromotive power output unit box 13. Since the degree of flexibility for installing respective components has been significantly extended and also the overall system has been made light and compact, a bicycle of an ordinary frame can be easily powered by electricity. <IMAGE>