| 摘要 |
Provided is an electrically assisted bicycle configured so that a transmission mechanism can be provided in a so-called motor drive unit and, in addition, so that discomfort and shock applied to the rider during transmission shifting can be limited to a minimum. A speed reduction mechanism (25) provided to a motor drive unit (20) comprises: a speed reduction gear wheel (36) for low speed; a speed reduction gear wheel (41) for high speed; a one-way clutch (51) for low speed, disposed between the speed reduction gear wheel (36) for low speed and a resultant force transmitting body (29); a one-way clutch (52) for high speed, disposed between the speed reduction gear wheel (41) for high speed and the resultant force transmitting body (29), and a selection clutch (45) provided so as to be capable of being engaged with and disengaged from the one-way clutch (52) for high speed. When engaged with the one-way clutch (52) for high speed, the selection clutch (45) sets the one-way clutch (52) for high speed to a free state, and when disengaged from the one-way clutch (52) for high-speed, the selection clutch (45) allows the one-way clutch (52) for high-speed to function. |
