Bicycle derailleur having positive speed position retention

Claim 1

In a bicycle derailleur comprising four members, a fixing member, two linkage members and a movable member mounting a chain guide, two members of said four members carrying a return spring between them so that the cooperative operation of a control cable comprising an inner wire and an outer sheath and the action of said return spring enables said movable member to reciprocate with respect to said fixing member for changing the bicycle speed, the improvement comprising: a control element for setting said movable member in a proper position corresponding to a desired speed change stage, said control element being supported to one of said four members and having a plurality of engageable portions corresponding to the number of speed change stages said movable member reciprocates among for changing the bicycle speed, said engageable portions having engaging faces for each speed change stage and connecting faces for interconnecting said engaging faces; a retainer engageable with a said engaging face at each of said engageable portions of said control element for retaining said movable member in a proper position corresponding to a desired speed change stage, said retainer being supported swingably to another member of said four members, said another member being relatively movable with respect to said one member carrying said control element; a spring urging said retainer in a first direction where said retainer engages with said engageable portions of said control element; and spring means for moving said retainer in a second direction where said retainer disengages from said engageable portions of said control element, said spring means for moving being provided adjacent said retainer and operable such that when said control wire is operated to allow said return spring to act to return said movable member said means for moving causes said retainer to be disengaged from said engageable portions.