A bicycle deraileur comprising a parallelogrammic linkage mechanism including a base member, a first link pivotally connected at one end thereof to the base member by a first pin, a second link pivotally connected at one end thereof to the base member by a second pin, and a movable member pivotally connected to the other ends of the first and second links by third and fourth pins respectively; a chain guide mechanism carried by the movable member; an operating member pivotally mounted on the firs pin for operation by a cable and provided with a pin; a torsion spring arranged on the first pin to engage with the operating member and the first link, the spring elastically urging the operating member to counteract a tension applied to the cable; and a restraining link pivotally connected at one end to the fourth pin and having a slot extending from the other end toward the fourth pin and slidably receiving the pin of the operating member.

A derailleur for a bicycle is provided with a base member, a movable member movable axially of a multistage sprocket assembly, a linkage member for moving the movable member axially of the multistage sprocket assembly, a guide mechanism supported to the movable member and guiding a driving chain from one sprocket to another at the multistage sprocket assembly, and a coiled return spring. At an intermediate portion of the linkage member there is a provided a support shaft for the spring, with the support shaft supporting the coiled portion of the spring. A first end portion of the spring is retained to the linkage member carrying the support shaft, and a second end portion of the spring is movably engaged with a member movable relative to the linkage member, thereby reducing the amount of deflection of the spring for a given amount of movement of the movable member.

An improved bicycle derailleur mechanism generally includes a bracket with two parallel spaced lugs extending perpendicularly therefrom, obliquely positioned on a first pivot member so that an inner cable extending through an adjuster nipple to a cable clamp on a parallelogram body is retained at a same angle when tension in the cable is adjusted by rotating the adjuster nipple, resulting in alignment between the derailleur mechanism and sprockets on a bicycle rear wheel remaining unchanged.

A twist-grip device for operating the gears of a bicycle includes indexing associated with the hand-grip for snap-locating the hand-grip in the various positions corresponding to the engagement of the various gear ratios. The device includes a spring which biasses the hand-grip in the opposite sense from the sense of biassing of the spring of the derailleur which effects the engagement of the various gear ratios. The device also includes a screw for adjusting the average torque which needs to be applied to the hand-grip to snap-rotate the hand-grip between two successive positions. The rotation of the screw varies the preloading of a resilient expandable bush associated with the indexing pin springs.

With an object of decreasing the size and weight of a derailleur and a control lever assembly by decreasing a difference in an elastic returning force between a beginning and ending phases of the pantograph link mechanism's deformation, the following technical is provided: The parallelogram pantograph link mechanism (7) is provided with a first and second pivotal members (12, 13) each having a predetermined length and pivoted to a predetermined position of a different constituent member of the parallelogram pantograph link mechanism (7), and respective ends of the first and second pivotal members (12, 13) are mutually connected by a pin for causing the first and second pivotal members (12, 13) to pivot relatively to the members to which they are respectively pivoted when the parallelogram pantograph link mechanism (7) is deformed; and a return spring (15) is provided between the first or second pivotal member (12 or 13) and a selected one of the constituent members of the parallelogram pantograph (15).