Derailleur for a bicycle

Abstract

A derailleur for a bicycle, which comprises four members, including a fitting member, two linkage members and a movable member, all movable with respect to each other. Between two of the members there is a device for positioning cages having chain-guide pulleys mounted on the movable member, whereby the derailleur enables the cages to be properly positioned and kept in the position at each speed-change stage of the bicycle so that an accurate and light speed-change operation may be performed.

What is claimed is: 
     
       1. A derailleur for a bicycle, which is pulled by .[.control wires.]. .Iadd.at least one control wire .Iaddend.to change the speed of the bicycle by moving a driving chain to a selective sprocket of a freewheel, said derailleur comprising: a. four members including a first fitting member, second and third linkage members each pivotally mounted at one end to said fitting member, and a fourth movable member pivotally supported at one end to each other end of said linkage members, said linkage members being swingable with respect to said fitting member and with respect to each other, said fourth movable member being swingable with respect to said linkage members and to said fitting member;   b. cages coupled to the other end of said fourth movable member and having two chain guide pulleys freely movable with said fourth movable member to move the driving chain; and   c. means, coupled on two of said four members which are movable with respect to each other, for maintaining the position of said cages, said maintaining mean including a holder on one of said two members and having a plurality of engageable portions, and a retainer on the other of said two members and engageable with any one of said engageable portions.   
     
     
       2. The derailleur according to claim 1, wherein said holder is on said fitting member, and said retainer is on another member movable with respect to said fitting member. 
     
     
       3. The derailleur according to claim 2, wherein said retainer is on said fourth movable member. 
     
     
       4. The derailleur according to claim 2, wherein said retainer is on one of said linkage members. 
     
     
       5. The derailleur according to claim 2, wherein said holder is formed of a plate extending from one end to another end toward said fourth movable member, said other end of said holder having said plurality of engageable portions, said engageable portions each having a given spaced interval therebetween along the path of motion said member carrying said retainer thereon and swingingly moving with respect to said fitting member. 
     
     
       6. The derailleur according to claim 1, wherein said holder is on said fourth movable member and said retainer is on another member movable with respect to said fourth movable member. 
     
     
       7. The derailleur according to claim 6, wherein said retainer is on said fitting member. 
     
     
       8. The derailleur according to claim 6, wherein said retainer is on one of said linkage members. 
     
     
       9. The derailleur according to claim 6, wherein said holder is formed of a plate extending from one end to another end toward said fitting member, said other end of said holder having said plurality of engageable portions, said engageable portions each having a given spaced interval therebetween along the path of motion of the member carrying said retainer thereon and swingingly moving with respect to said fourth movable member. 
     
     
       10. The derailleur according to claim 1, wherein said holder is on one of said linkage members and said retainer is on another member movable with respect to said one linkage member carrying said holder thereon. 
     
     
       11. The derailleur according to claim 10, wherein said retainer is on the other of said linkage members, said linkage members being opposite one another. 
     
     
       12. The derailleur according to claim 10, wherein said retainer is on said fitting member. 
     
     
       13. The derailleur according to claim 10, wherein said retainer is on said fourth movable member. 
     
     
       14. The derailleur according to claim 10 wherein said one of said linkage members includes a vertical wall and a horizontal wall extending at a right angle to said vertical wall, said horizontal wall including said holder, and further comprising carrier means connected to the other of said linkage members, said retainer being mounted on said carrier means, said linkage members being opposite one another. 
     
     
       15. The derailleur according to claim 1, wherein said retainer comprises a ball and a helical coiled spring urging the ball toward said holder. 
     
     
       16. The derailleur according to claim 1, wherein the engageable portions of said holder include dish-like shaped recesses, respectively, said recesses being interconnected with each other by means of chevron shaped intervals. 
     
     
       17. The derailleur according to claim 1, wherein said engageable portions of said holder include first permanent magnets, respectively, and said retainer includes a second permanent magnet which faces any one of said first magnets, the magnetic poles of said first and second magnets facing each other being different from one another. 
     
     
       18. The derailleur according to claim 17, wherein said first magnets are spaced apart from one another and further comprising at each spaced interval between said first permanent magnets a third permanent magnet, said second magnet and said third magnet facing each other with the same magnetic pole. 
     
     
       19. A derailleur for a bicycle, which is pulled by .[.control wires.]. .Iadd.at least one control wire .Iaddend.to move cages having two chain guide pulleys to move a driving chain to a selective sprocket of a freewheel to change the speed of the bicycle, said derailleur comprising: a. four members including a first fitting member, second and third linkage members each pivotally mounted at one end to said fitting member, and a fourth movable member pivotally mounted at one end to each other end of said linkage members, said linkage members being swingable with respect to said fitting member and with respect to each other, said fourth movable member being swingable with respect to said linkage members and to said fitting member, said fourth movable member at its other end being connectable to the cages; and   b. means for maintaining the position of the cages including a holder having a plurality of engageable portions, and a retainer selectively engageable with any one of said engageable portions, wherein one of said holder and said retainer is mounted swingingly on one of said four members so that the position of said holder and said retainer is adjustable relative to each other.   
     
     
       20. The derailleur according to claim 19, wherein said holder is pivotally mounted on said one of said four members so that the position of said holder is adjustable relative to said retainer, and further comprising fixing means for fixing said holder on said one member in an adjusted position. 
     
     
       21. The derailleur according to claim 19, wherein said retainer is pivotally mounted on said one of said four members so that the position of said retainer is adjustable relative to said holder, and further comprising fixing means for fixing said retainer on said one member in an adjusted position. 
     
     
       22. The derailleur according to claim 21 wherein said fixing means includes an adjuster pivotally mounted on one of said linkage members, said retainer being mounted on said adjuster, and an adjusting bolt to move said adjuster to adjust and fix said retainer in the adjusted position. 
     
     
       23. A derailleur for a bicycle which is pulled by control wires to move cages having two chain guide pulleys to move the driving chain to a selective sprocket of a freewheel to change the speed of the bicycle, said derailleur comprising: a. four members including a first fitting member, second and third linkage members each pivotally mounted at one end to said fitting member, and a fourth movable member pivotally mounted at one end to each other end of said linkage members, said linkage members being swingable with respect to said fitting member, said fourth movable member being swingable with respect to said fitting member and to said linkage members, said fourth movable member at its other end being connectable to the cages;   b. .[.means, connected to at least one of said four members, for maintaining the position of the cages;.]. .Iadd.means, coupled on two of said four members which are movable with respect to each other, for maintaining the position of said cages, said maintaining means including a holder on one of said two members and having a plurality of engageable portions, and a retainer on the other of said two members and engageable with any one of said engageable portions; .Iaddend.and   c. means, between said fitting member and another of said four members movable with respect to each other, for moving said fourth movable member, including two control wires, a movable plate having two arms respectively retaining terminals of said wires, and a plate fixed to said fitting member and opposite said movable plate, said fixed plate having means for guiding said wires to said movable plate.   
     
     
       24. The derailleur according to claim 23, wherein said fixed plate including means for guiding said wires has a pin fixed thereto, and said movable plate has a fork end having a cutout engageable with said pin so that said movable plate may be turned under regulation of said cutout and pin. 
     
     
       25. The derailleur according to claim 23, further comprising a lever means to operate said two wires, said lever means comprising a rotatable body for winding-up said wires thereon, and a handle extending from said body for rotatably operating said body so that said body may be rotatable in a first direction and a second direction which is the reverse of said first direction. .Iadd. 26. The derailleur according to claim 1, further comprising a lever means to operate said at least one control wire, said lever means comprising a rotatable body for winding-up said wire thereon, and a handle extending from said body for rotatably operating said body so that said body may be rotatable in a first direction and a second direction which is the reverse of said first direction. .Iaddend.