Linear derailleur mechanism

Abstract

A derailleur system is provided that moves the derailleur cage in a substantially rectilinear path. The derailleur is mounted to a frame having a gear cassette mounted thereon. The gear cassette includes an axis of rotation. The derailleur includes a drive member engaging the gear cassette. The derailleur is positioned on the frame adjacent the gear cassette, and including a spatial linkage having a stationary link, a floating link, and a cage assembly having two pulleys each defining an axis of rotation. The drive member engages each of the pulleys. The path of the floating link is substantially linear through substantially its entire range of motion and variously aligns at least one of the pulleys with the gear cassette.

We claim: 
     
         1 . A bicycle comprising:
 a frame having a gear cassette mounted thereon, the gear cassette having an axis of rotation;   a drive member engaging the gear cassette;   a derailleur positioned on the frame adjacent the gear cassette, with the derailleur having a cage assembly with two pulleys each defining an axis of rotation and the drive member engaging each of the pulleys, wherein the derailleur also includes a spatial linkage having:
 a stationary link and a floating link wherein the path of the floating link is substantially linear through substantially its entire range of motion. 
   
     
     
         2 . The bicycle of  claim 1 , wherein the gear cassette is a rear gear cassette operably associated with a rear wheel. 
     
     
         3 . The bicycle of  claim 1 , wherein the gear cassette is a front chain ring set operably associated with a crank. 
     
     
         4 . The bicycle of  claim 1 , wherein the pulley axes of the cage assembly is parallel to the axis of rotation of the gear cassette and remains parallel to the axis of rotation of the gear cassette throughout its entire range of motion. 
     
     
         5 . The bicycle of  claim 1 , wherein the pulley axes of the cage assembly is not parallel to the axis of rotation of the gear cassette and remains not parallel to the axis of rotation of the gear cassette throughout its entire range of motion. 
     
     
         6 . The bicycle of  claim 1 , wherein the spatial link is an over-constrained spatial 6R linkage. 
     
     
         7 . The bicycle of  claims 1 , wherein the stationary link is attached to the bicycle frame. 
     
     
         8 . The bicycle of  claim 1 , wherein the cage assembly is pivotally connected concentrically on the floating link. 
     
     
         9 . The bicycle of  claim 1 , wherein the cage assembly is pivotally connected eccentrically on the floating link. 
     
     
         10 . The bicycle of  claim 1 , wherein an actuation force is applied to the derailleur to cause motion from a first position to a second position, and at least one return mechanism is utilized to urge the derailleur from the second position towards the first position. 
     
     
         11 . The bicycle of  claim 10 , wherein the actuation force may be a mechanically, electrically, or hydraulically driven. 
     
     
         12 . The bicycle of  claim 11 , wherein the return mechanism may include at least one spring selected from one of the group of a torsion spring, and/or an extension spring. 
     
     
         13 . The bicycle of  claim 11 , wherein input activation of the linkage is via a mechanical cable. 
     
     
         14 . The bicycle of  claim 11 , wherein input activation of the linkage is via an electronic servo. 
     
     
         15 . The bicycle of  claim 11 , wherein the input activation of the linkage is via a plunger. 
     
     
         16 . A derailleur for a bicycle comprising:
 a stationary link and a floating link wherein the path of the floating link is substantially linear through substantially all of the floating link's range of motion, wherein the floating link is operable to move a drive member which is operable to engage a gear cassette, wherein the stationary link is operable to be positioned on a frame having the gear cassette mounted thereon, the gear cassette having an axis of rotation, wherein the stationary link is positioned on the frame adjacent the gear cassette.   
     
     
         17 . A derailleur of  claim 16 , wherein the gear cassette is a rear gear cassette operably associated with a rear wheel. 
     
     
         18 . A derailleur of  claim 16 , wherein the gear cassette is a front gear cassette operably associated with a crank. 
     
     
         19 . The derailleur of  claim 16 , wherein the pulley axes of the cage assembly remain parallel to the axis of rotation of the gear cassette throughout its entire range of motion. 
     
     
         20 . The derailleur of  claim 16 , wherein the spatial link is an over-constrained spatial 6R linkage. 
     
     
         21 . The derailleur of  claim 16 , wherein the stationary link is connected to the bicycle frame. 
     
     
         22 . The derailleur of  claim 16 , wherein the cage assembly is pivotally connected concentrically on the floating link. 
     
     
         23 . The derailleur of  claim 16 , wherein the cage assembly is pivotally connected eccentrically on the floating link. 
     
     
         24 . The derailleur of  claim 16 , wherein an actuation force is applied to the derailleur to cause motion from a first position to a second position, and at least one return mechanism is utilized to urge the derailleur from the second position towards the first position. 
     
     
         25 . The derailleur of  claim 24 , wherein the actuation force is a mechanically, electrically, or hydraulically driven. 
     
     
         26 . The derailleur of  claim 24 , wherein the return mechanism includes at least one spring selected from one of the group of a torsion spring, and/or an extension spring. 
     
     
         27 . The derailleur of  claim 25 , wherein input activation of the linkage is via a mechanical cable. 
     
     
         28 . The derailleur of  claim 25 , wherein input activation of the linkage is via an electronic servo. 
     
     
         29 . The derailleur of  claim 25 , wherein the input activation of the linkage is via a piston. 
     
     
         30 . A bicycle comprising:
 a frame having a gear cassette mounted thereon, the gear cassette having an axis of rotation;   a drive member engaging the gear cassette;   a derailleur positioned on the frame adjacent the gear cassette, with the derailleur having a stationary link and a floating link, wherein the stationary link is connected to the floating link via a first linkset and a second linkset, each linkset having a plurality of axis of rotation, wherein the axes of rotation in the first link set are not parallel to the axes of ration in the second linkset.