| 摘要 |
A toothed wheel (10) of a chain transmission for a bicycle is described, intended to be coupled with a further toothed wheel (3) with a smaller diameter in a group of toothed wheels integral in rotation. The toothed wheel (10) comprises a plurality of teeth (13) which follow each other on the toothed wheel (10) separated by spaces (14) according to a direction of rotation (R) of the toothed wheel (10), in which each tooth (13) has a thickness, a width and a height and has a lead side (31), a following side (32), a front side (33) and a rear side (34). The toothed wheel (10) is characterised in that it comprises at least one among: a front bevel (50) on at least one tooth of first disengagement (13ps) of said plurality of teeth (13), such a front bevel (50) extending between the front side (33) and the lead side (31); a rear bevel (60) on at least one tooth of last engagement (13ua) of said plurality of teeth (13), such a rear bevel (60) extending between the rear side (34) and the following side (32). <??>Each of the two bevels (50, 60) contributes to easing the downwards gear-change, i.e. the displacement of the chain (2) from the toothed wheel (10) with a larger diameter to the toothed wheel with a smaller diameter (3). <IMAGE>
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