Low profile rear derailleur

A bicycle rear derailleur comprising:

• a base member;
• an extension member structured to be mounted to a rear frame end of a bicycle frame, wherein the extension member is a separate member from the bicycle frame;
• wherein the extension member has a first end for coupling to the bicycle frame and a second end for coupling to the base member;
• a movable member that supports a chain guide including a pulley that rotates around a pulley axis, wherein the pulley has a pulley plane that bisects the pulley and is substantially perpendicular to the pulley axis;
• a first linking member coupled between the base member and the movable member so that the chain guide moves laterally relative to the base member between a first lateral position and a second lateral position;
• wherein the base member comprises:
• a mounting portion mounted to the second end of the extension member for mounting the base member to a bicycle frame so that the second end of the extension member and the mounting portion are disposed behind the first end of the extension member;
• and
• a link coupling portion for coupling the first linking member to the mounting portion;
• wherein the link coupling portion comprises:
• a laterally inner link mounting projection that includes a laterally inwardly facing surface and a laterally outwardly facing surface;
• and
• a laterally outer link mounting projection that includes a laterally inwardly facing surface and a laterally outwardly facing surface;
• and
• wherein the first linking member comprises:
• a first coupling projection disposed at the laterally inwardly facing surface of the laterally inner link mounting projection, and
• a second coupling projection disposed at the laterally outwardly facing surface of the laterally outer link mounting projection;
• a first pivot shaft disposed at the first coupling projection and at the laterally inner link mounting projection to couple the first linking member to the base member;
• and
• a separate second pivot shaft disposed at the second coupling projection and at the laterally outer link mounting projection to couple the first linking member to the base member;
• wherein the first linking member pivots relative to the base member around a first pivot axis;
• wherein the pulley plane is disposed between the first pivot shaft and the second pivot shaft and is non-parallel to the first pivot axis;
• wherein the first pivot shaft and the second pivot shaft have respective first and second surfaces that face in directions towards each other, wherein the first and second surfaces do not contact each other when the first linking member is coupled to the base member.

A bicycle rear derailleur comprising:

• a base member;
• a movable member that supports a chain guide including a pulley that rotates around a pulley axis, wherein the pulley has a pulley plane that bisects the pulley and is substantially perpendicular to the pulley axis;
• a first linking member coupled between the base member and the movable member so that the chain guide moves laterally relative to the base member between a first lateral position and a second lateral position;
• wherein the base member comprises:
• a mounting portion for mounting the base member to a bicycle frame;
• and
• a link coupling portion for coupling the first linking member to the mounting portion;
• wherein the link coupling portion comprises:
• a laterally inner link mounting projection that includes a laterally inwardly facing surface and a laterally outwardly facing surface;
• and
• a laterally outer link mounting projection that includes a laterally inwardly facing surface and a laterally outwardly facing surface;
• a first pivot shaft disposed at the laterally inner link mounting projection to couple the first linking member to the base member;
• and
• a separate second pivot shaft disposed at the laterally outer link mounting projection to couple the first linking member to the base member;
• wherein the first pivot shaft and the second pivot shaft have respective first and second surfaces that face in directions towards each other, wherein the first and second surfaces do not contact each other when the first linking member is coupled to the base member;
• wherein the first linking member pivots relative to the base member around a common axis that extends through the laterally inner link mounting projection and through the laterally outer link mounting projection;
• wherein the pulley plane is disposed between the first pivot shaft and the second pivot shaft and is non-parallel to the common axis;
• and
• wherein a thickness between the laterally inwardly facing surface and the laterally outwardly facing surface of one of the inner link mounting projection or the laterally outer link mounting projection at the common axis is greater than a thickness between the laterally inwardly facing surface and the laterally outwardly facing surface of the other one of the inner link mounting projection or the laterally outer link mounting projection at the common axis.