Indexed cycle derailleur

A cycle gear shift derailleur adapted to change positions of a cycle drive gear chain from a first cycle sprocket gear to an adjacent second sprocket gear that is coaxially fixed with respect to said first cycle sprocket gear, said derailleur comprising a shift indexer, wherein said shift indexer is integrally affixed to said derailleur, wherein said indexer comprises a physical part of said derailleur structure, and is activated by a gearshift control cable wire, said indexer comprising a detent-style, spring-loaded protuberance and said derailleur comprises an upper deformable parallelogram having a lower pulley cage portion secured to and supported by one leg of said parallelogram;

• said derailleur further comprising a first leg adapted to be fixed to a cycle frame, a second leg having a derailleur chain guide affixed thereto, said first and second legs adapted to move with respect to one another and comprising substantially parallel structures connected together via two links to define a deformable parallelogram-shaped four-bar linkage mechanism, wherein said shape of said parallelogram is controlled between two limits of movement via a shift derailleur cable wire extending through a sheath having a housing affixed to said first leg, and said cable having an end affixed to one of said links;
• said cable thereby adapted to control shifting of gear chain positions between said first and second cycle sprocket gears via follower movements of said chain guide through which the gear chain passes,
• and wherein said gearshift derailleur shift indexer is directly affixed to said four-bar linkage mechanism, whereby said indexer accuracy is unaffected via control cable stretching.

A gear shifter system for a cycle comprising a gear cluster including at least two sprocket gears;

• said gears positioned coaxially in a side-by-side relationship, and adapted to receive a drive gear chain alternately passing over at least one of said gears of said gear cluster;
• a derailleur positioned proximally to each of said gears in said gear cluster, said derailleur having a chain guide for controlling passage therethrough of said drive gear chain;
• a shift indexer for positively positioning said chain on either one of said sprocket gears, and a pulley carriage gear attached to the chain guide;
• said system further comprising an actuator for transversely moving said derailleur to shift the chain from said one of the gears in said cluster to a next adjacent gear when said actuator is positively moved in one transverse direction, and to shift the chain from said next adjacent gear back to said one cluster gear when said actuator is moved in an opposite direction, wherein said actuator is a deformable parallelogram, and wherein a transverse movement of said indexer relative to said derailleur causes a corresponding movement of said pulley carriage gear attached to said chain guide, said pulley carniage gear having teeth adapted to engage said chain, and to thereby laterally displace said chain to effect a shifting of the chain from a first lateral position on said one gear to an adjacent lateral position on the next adjacent gear;
• said indexer being directly affixed to said derailleur.

A cycle gear shift derailleur adapted to change positions of a cycle drive gear chain from a first selectable sprocket gear to an adjacent second sprocket gear that is coaxially fixed with respect to said first cycle sprocket gear;

• a shift indexer, wherein said shift indexer is integrally affixed to said derailleur, and wherein said indexer thereby comprises a physical part of said derailleur structure, and wherein said indexer activated by a gearshift control cable wire;
• said indexer further comprising a cooperating elongated piston sleeve and cylinder arrangement, wherein said sleeve is housed within, and adapted to move reciprocally within, said cylinder;
• said derailleur comprising an upper deformable parallelogram having a lower pulley cage portion secured to and supported by one leg of said parallelogram;
• said derailleur further comprising a first leg adapted to be fixed to a cycle frame, a second leg having a derailleur chain guide affixed thereto, said first and second legs adapted to move with respect to one another and comprising structures connected together via links to define a deformable parallelogram linkage mechanism, wherein said shape of said parallelogram is controlled between two limits of movement via a derailleur cable wire attached to said piston sleeve and cylinder arrangement;
• wherein the cylinder is affixed to said first leg;
• said cylinder including a slot transversely oriented with respect to said piston sleeve, and said piston sleeve including a series of ring grooves, each ring groove corresponding to one selectable sprocket gear position;
• a tension clip axially fixed in said slot transverse to each of said ring grooves of said piston sleeve within said cylinder, wherein said tension clip is displaced from one ring groove to an adjacent ring groove via a threshold force imposed on said piston sleeve via said cable, wherein said cable has an end affixed to one of said links;
• said cable being thereby adapted to control shifting of gear chain positions between said first and second cycle sprocket gears via follower movements of said chain guide through which the gear chain passes,
• and wherein said shift indexer is directly affixed to said deformable parallelogram linkage of said derailleur, whereby said indexer accuracy with respect to gear sprocket selection is unaffected via stretching of said cable wire.