| 摘要 |
<p>The bicycle is suitable both for tourist and sporting purposes, in particular for mountain riding, and permits of better graduating the cyclist's exertion in order to improve athletic performance with regard to his or her physical condition. The bicycle is equipped with a front gearshift (C) for the derailing of the chain (B) across the series of front multiplying gears, which gears are constituted by two or more multiplying gears, at least one of which differ from the first multiplying gear engaged by the chain (8) by a small number of cogs; the front gearshift (C) being constituted by an articulated parallelogram (23, 24, 36, D) equipped with a pair of derailling wings (A1, A2), not staggered in height, having either circular crown arc profile tapered backwards, or in the shape of a downturned 'L'. An oscillating arm may be attached to the connecting rod of the said articulated parallelogram, which arm supports in rotation at its posterior end a guide device for the chain (8) comprising a couple of wheels (82, 100) bilaterally vertically opposed; the derailleur device may also be constituted by an elastic device oscillating in a vertical plane posteriorly equipped with a cogged wheel (82) inferiorly engaging with the chain (8).</p> |
