| 摘要 |
Provided is an electric assist bicycle that can add sufficient auxiliary drive force while enabling smooth speed change and preventing an increase in the frequency of replacing components such as the chain, that causes no interference problem between a mount or a battery and a front derailleur, and that does not require the development of a dedicated front derailleur. A crank shaft (7a) to which human power drive force from pedals is transmitted and a motor (21) are disposed so as to rotate about mutually different axes. On an outer periphery of the crank shaft (7a), a human power transmission member (29) to which the human power drive force is transmitted is disposed. On the outer periphery of the crank shaft (7a), a combined force transmission member (29) to which combined force combining the human power drive force and auxiliary drive force from the motor (21) is transmitted is disposed. The motor drive unit (20) is provided with a planetary gear mechanism (50) for changing the speeds of the combined force combining the human power drive force and the auxiliary drive force from the motor (21). |
