The Shimano Ultegra RD-R8150 is a Di2 electronic rear derailleur for 2x12-speed road drivetrains, taking cassettes up to 34T.

• Ultegra Di2, 12-speed (2x12)
• Single cage fits low sprockets of 28T to 34T
• Shifts 58% faster than the previous RD-R9150 (per Shimano)
• Wider range capacity than earlier models
• LED status/battery indicator with pairing and adjust modes