| 摘要 |
The invention can be applied to a bicycle with pedals of the type having a driven rear wheel provided, on its axle, with a toothed pinion actuated by a chain 43 driven by a large sprocket 42. According to the invention, the said large sprocket 42 is keyed onto the output shaft 24 of a gear change box whose input shaft 18 is made to rotate by a symmetric pair of toothed pinions 16, 17 revolving idly in the opposite rotational direction to that which causes the forward travel of the bicycle. These pinions are actuated by toothed sectors 14, 15 securely fastened to a pair of pedal cranks 10, 11 with an oscillatory movement about a practically horizontal intermediate position. <IMAGE>
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