Bicycle rear derailleur

Abstract

A derailleur includes a base member for attachment to a bicycle frame and a movable member supporting a chain guide such that the chain guide moves laterally to shift a chain among a plurality of gears. The base member has a laterally inner surface and a laterally outer surface, and it includes a projection extending laterally outwardly for engaging a corresponding recess in the frame.

What is claimed is:  
     
         1 . A derailleur comprising: 
 a base member for attachment to a bicycle frame, wherein the base member has a laterally inner surface and a laterally outer surface, wherein the base member includes a projection extending laterally outwardly for engaging a corresponding recess in the frame; and    a movable member supporting a chain guide such that the chain guide moves laterally to shift a chain among a plurality of gears.    
     
     
         2 . The derailleur according to  claim 1  wherein the base member includes an opening for receiving a fastener therethrough to attach the base member to the bicycle frame, wherein the projection is disposed in close proximity to the opening.  
     
     
         3 . The derailleur according to  claim 1  wherein the base member is one-piece.  
     
     
         4 . The derailleur according to  claim 1  wherein the movable member is coupled to the base member through at least one directly connected link.  
     
     
         5 . The derailleur according to  claim 1  wherein the projection comprises: 
 a first side wall; and  
 a second side wall oriented substantially parallel to the first side wall.  
 
     
     
         6 . The derailleur according to  claim 5  wherein the first side wall is substantially straight, and wherein the second side wall is substantially straight.  
     
     
         7 . The derailleur according to  claim 5  wherein the projection further comprises a third side wall extending between the first side wall and the second side wall.  
     
     
         8 . The derailleur according to  claim 7  wherein the first side wall is substantially straight, wherein the second side wall is substantially straight, and wherein the third side wall is substantially straight.  
     
     
         9 . The derailleur according to  claim 8  wherein the third side wall is substantially perpendicular to the first side wall and to the second side wall.  
     
     
         10 . A derailleur apparatus comprising: 
 a frame member having an axle opening for receiving an axle therethrough and a slot in close proximity to the axle opening;    a base member attached to a laterally inner surface of the frame member, wherein the base member has a laterally inner surface and a laterally outer surface, wherein the base member includes a projection extending laterally outwardly into the slot in the frame member; and    a movable member supporting a chain guide such that the chain guide moves laterally to shift a chain among a plurality of gears.    
     
     
         11 . The derailleur according to  claim 10  wherein the projection has a width substantially equal to a width of the slot.  
     
     
         12 . The derailleur according to  claim 10  wherein the slot has a width substantially equal to a width of the axle opening.  
     
     
         13 . The derailleur according to  claim 10  further comprising a fastener extending through an opening in the base member for attaching the base member to the bicycle frame, wherein the projection is disposed in close proximity to the opening.  
     
     
         14 . The derailleur according to  claim 10  wherein the base member is one-piece.  
     
     
         15 . The derailleur according to  claim 10  wherein the movable member is coupled to the base member through at least one directly connected link.  
     
     
         16 . The derailleur according to  claim 10  wherein the projection comprises: 
 a first side wall; and  
 a second side wall oriented substantially parallel to the first side wall.  
 
     
     
         17 . The derailleur according to  claim 16  wherein the first side wall is substantially straight, and wherein the second side wall is substantially straight.  
     
     
         18 . The derailleur according to  claim 16  wherein the projection further comprises a third side wall extending between the first side wall and the second side wall.  
     
     
         19 . The derailleur according to  claim 18  wherein the first side wall is substantially straight, wherein the second side wall is substantially straight, and wherein the third side wall is substantially straight.  
     
     
         20 . The derailleur according to  claim 19  wherein the third side wall is substantially perpendicular to the first side wall and to the second side wall.  
     
     
         21 . The derailleur according to  claim 16  wherein a width of the projection between the first wall and the second wall is substantially equal to a width of the slot.  
     
     
         22 . The derailleur according to  claim 21  wherein the width of the slot is substantially equal to a width of the axle opening.