To rapidly and smoothly shift a chain from a small sprocket to a large sprocket.
A shift assist projection 20 is provided on a large sprocket S2 to assist the shift of a chain C from a small sprocket S1 to the large sprocket S2. The shift assist projection 20 extends axially from one side of the sprocket S2. The shift assist projection 20 has a chain receiving face 74 facing a center plane P and teeth of the large sprocket S2. The chain receiving face 74 is inclined to a predetermined angle changing with respect to the center plane P of the large sprocket S2. When the chain C is shifted from the small sprocket S1 to the large sprocket S2, the aftermost rotational edge of the chain receiving face 74 is at the position closer to the center plane from a foremost rotational edge when viewed substantially along the moving direction of the chain C.
NISHIMOTO YUSUKE
TEZUKA TOSHIO
Yamashita
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