SunRace RDM900 9-Speed Rear DerailleurSunRace RDM900 9 Speed Rear Derailleur The SunRace RDM900 is built for riders who want serious gear range without the complexity or cost of modern high speed drivetrains. Designed around a wide range 11 to 50T cassette, it delivers the climbing ability and versatility needed for gravel, MTB, touring, city bikes and e bikes, while retaining the simplicity and durability of a 9 speed system. A key advantage of the RDM900 is its 1: 1. 7 pull ratio,