Rear

M21 rear derailleurs are designed to work with 6- and 7-speed Shimano road and mountain shifters. Enjoy the wide variety of bikes you can get going again with M21 rear derailleurs. - Robust composite and steel construction - Compatible with Shimano 6- and 7-speed mountain and road systems - Long cage for double or triple cranksets and 32T max cassette cog - Includes frame hanger attachment for use with older frame designs

R-series rear derailleurs are designed to work with 7, 8, 9, and 10-speed Shimano-compatible road shifters. These R10 aluminum rear derailleurs are lightweight, precision CNC-machined, robust, and can get any bike back on the road. - Lightweight all-aluminum construction - Compatible with Shimano 7, 8, 9, and 10-speed road systems - Not compatible with Shimano Tiagra 4700 road system - Short cage for double crankset and 28T max cog - Medium cage for double crankset and 34T max cog