Patent ID: 7771303

Claim:
A chain guide device adapted to be mounted on a swing arm for supporting a rear wheel driven by a chain by way of a chain guide stay, comprising: an inner side wall; an outer side wall, said inner side wall and said outer side wall being arranged along left and right sides of the chain as portions of a wall portion of a chain passage with the chain penetrating therethrough in a longitudinal direction; and a front end portion of the inner side wall being positioned behind a front end portion of the outer side wall, wherein the front end portion of the inner side wall is formed contiguously with an inner surface of a lower boss by way of a stepped portion which steps inwardly toward the chain at a forward end of the chain guide device, wherein the inner surface of the lower boss is disposed forwardly of the stepped portion, and is parallel to and disposed inwardly with respect to a rear end portion of the inner side wall.