| 摘要 |
A gear crank apparatus for a bicycle, comprising a crank shaft, a pair of crank arms, and at least one chain gear. The chain gear has an ellipse-like shape and peripheral teeth located on different pitch diameters, the chain gear being arranged with respect to the crank arms and being coupled therewith, so that when torque produced by a cyclist's leg during pedalling is maximum, the gear diameter for transmitting the torque from the chain gear to a driving chain becomes substantially minimum and when the torque is a minimum, the gear diameter becomes substantially a maximum. |
