| 摘要 |
<p>The invention relates to a crank gear box configured like a casing fixed to a bicycle frame, specifically in the region where is provided the input shaft or pedal shaft which is coupled to the casing. There is also a rear shaft or axis coupled to the casing and which receives a rotary motion from the input shaft, with interposition of a transmission mechanism. Finally, the rotary motion of the rear shaft will be transmitted to a toothed plate and, from the latter, to a gear carried by the rear drive wheel of the bicycle. Naturally, the bicycles are provided with two controls in order to carry out the gear shifting operations. With the disclosed system, the gear shifting operations will be smooth, without the occurrence of torsions and sudden variations of torsions in the chain, as it is occurring frequently with conventional systems.</p> |
