Shimano xtr di2 m9050 11 speed rear mechshimanos first mountain bike specific di2 rear derailleur is also its most technologically advanced introducing shimano shadow rd stabilization to di2 the rd m9050 couples unrivaled chain control that aggressive riders have come to love with shift performance that doesnt degrade over time whether cross country or trail riders run a 1x 2x or 3x drivetrain the ultra narrow profile help protect the drivetrain in tight trail sections the refined rear