| 摘要 |
To reduce the load alternately imposed on the rider's legs when the pedals are stepped and to use the muscle of the entire legs in a well balanced manner, thereby naturally returning the pedals to the initial position of the stepping operation without forming an unnatural bending state of each leg at the returning track of the pedal. A crank mechanism for a bicycle comprises a main crank 9, a follower crank 12, and a connecting lever 15 disposed between free ends of the cranks 9, 12, a second fixed fulcrum shaft 11 of the follower crank 12 being arranged at a location obliquely upward and backward of a first fixed fulcrum shaft 8 of the main crank 9, the follower crank 12 being extended downward beyond a line L2 connecting the first and second fixed fulcrum shafts 8, 11 from the second fixed fulcrum shaft 11 such that a second free fulcrum shaft 11 at its free end is swung below the line L2 connecting the first and second fixed fulcrum shafts 8, 11, a pedal 16 being attached to a projection end 17 in the vicinity of a first free fulcrum shaft 13 of the lever 15 and arranged in the vicinity of the free end of the main crank 9, the pedal 16 being rotated along a non-circular track T passing through the first and second fixed fulcrum shafts 8 and 11, and the first fixed fulcrum shaft 8 being located at an internal area of the track T.
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