Patent ID: 7721621
Filing Date: 2010-05-25
Classification: B62M,Y10T

Abstract:
1. A bicycle shift control mechanism comprising: an operating member movable between a rest position and a shift releasing position; a wire take up member configured and arranged to rotate about a rotational axis in response to movement of the operating member; a positioning ratchet configured and arranged to rotate with the wire take up member, the positioning ratchet including a plurality of positioning teeth and a plurality of movement restricting teeth that are different from the positioning teeth, the positioning ratchet being mounted about a main pivot axis with the positioning teeth and the movement restricting teeth of the positioning ratchet being arranged with respect to the main pivot axis so that the positioning teeth form a stair shaped arrangement and the movement restricting teeth form another stair shaped arrangement, with outermost radial tips of the positioning teeth lying along a first curved path having a center of curvature that is offset from the main pivot axis and outermost radial tips of the movement restricting teeth lying along a second curved path having a center of curvature that is offset from the main pivot axis; and a position maintaining pawl including a position maintaining portion and a movement restricting portion which are located to engage the positioning ratchet at different peripheral locations of the positioning ratchet, the position maintaining portion and the movement restricting portion being pivotally mounted about a single pivot axis to alternately engage the positioning ratchet in a single shift operation, the position maintaining portion selectively holding the positioning ratchet in one of a plurality of predetermined shift positions by engaging one of the positioning teeth of the positioning ratchet when the position maintaining pawl is in a position maintaining position and the operating member is in the rest position, the position maintaining pawl being moved from the position maintaining position to a position releasing position to release the positioning ratchet upon movement of the operating member from the rest position to the shift releasing position such that the movement restricting portion of the position maintaining pawl engages one of the movement restricting teeth of the positioning ratchet to restrict movement of the positioning ratchet after release of the positioning ratchet from the position maintaining portion when the operating member is in the shift releasing position, the movement restricting teeth being arranged such that neither the position maintaining portion nor the movement restricting portion of the position maintaining pawl engages the movement restricting teeth in any of the predetermined shift positions when the operating member is in the rest position.