Derailleur for a bicycle

Claim 1

A bicycle derailleur operated by a control cable having a wire and a sheath for changing the bicycle speed by positioning a chain on a selected one of a plurality of sprockets, comprising: (a) four members, which include a base member, two linkage members pivoted to said base member, and a movable member pivoted to said linkage members and having cages carrying driving chain guide pulleys, said movable member being movable in reciprocation axially of the sprockets and with respect to said base member, one of said linkage members having an access hole therein, (b) an L-shaped control member swingable independently from said four members having an arm onto which is mounted means for attaching thereto one of said wire and sheath of the control cable, an arm pivotally mounted to one of said movable member and base member, and an engageable projection extending toward one of said two linkage members, (c) a pair of plates for storing energy, said plates being mounted to one of said linkage members to sandwich said linkage member in the relation of moving toward or away from said one linkage member, said plates being engaged therebetween with said engageable projection, (d) a spring urging said pair of plates toward said one linkage member for storing energy, and (e) a positioning and maintaining means provided between said control member and one of said four members to position and maintain the movable member with respect to the base member, said positioning and maintaining means comprising a retainer carrying a rolling body attached to said control member as a first cooperating means and an extension movable with one of said movable member and base member having a series of recesses therein as a second cooperating means which position said driving chain guide cages carried by said movable member.