| 摘要 |
<p>A sprocket assembly (12) for a bicycle (10) is provided with at least one large sprocket (S) and at least one small sprocket. The large sprocket (S) is modified to allow a bicycle chain (23) to move smoothly from the large sprocket (S) to the small 1 sprocket during an up shift operation. The large sprocket (S) basically has a sprocket body (40) with a first axial side (40a) and a second axial side (40b), and a plurality of circumferentially spaced teeth (A3-K3) extending radially and outwardly from an outer periphery of the sprocket body (40). The teeth (A3-K3) of the sprocket (S) include a plurality of up shift teeth (A3-E3). The up shift teeth (A3-K3) have at least a first up shift tooth (A3), a second up shift tooth (B3) located adjacent the first up shift tooth (A3) and a third up shift tooth (C3) located adjacent the second up shift tooth (B3). The first, second and third up shift teeth (A3, B3, C3) are dimensioned to maintain alignment of a bicycle chain (23) to prevent an up shift of the chain (23) when an outer link plate (23b) of the bicycle chain (23) meshes with the second up shift tooth (B3), and to permit an up shift of the bicycle chain (23) when an inner link plate (23a) meshes with the second up shift tooth (B3) along a first up shift path.</p> |
