US Patent 7780558 Bicycle rear derailleur

The chain guide of a bicycle rear derailleur is a chain guide which is connected to a movable member so that this guide is free to swing about a center pivot axis. The chain guide has a pair of plate members rotatably supporting a guide pulley and a tension pulley. One of the plate members is provided with a chain slip prevention part which is disposed between both plate members in the vicinity of the guide pulley. Preferably, the chain slip prevention part has a width of ten mm or greater and fifty mm or less.