What Our Gearhead(R) Experts Are Saying: "I've set this up on a race-ready XC build, and the response is instant. The wireless Di2 system keeps the cockpit clean, and shifts stay crisp even under load thanks to Hyperglide+. When paired with an EP801 drive unit, FREE SHIFT is a game changer-being able to shift while coasting feels seamless on rolling terrain. It's premium, but the performance backs it up." When we're building a no-compromise trail or XC machine, shifting performance has to be flawless. The Shimano XTR Di2 RD-M9250-GS Drivetrain Upgrade Kit brings wireless precision and race-proven engineering to our 1x12 setup, delivering lightning-fast response in a sleek, fully integrated system. At the heart of the kit is the XTR RD-M9250-GS short cage rear derailleur, optimized for 10-45T cassettes. Hyperglide+ technology ensures smooth, secure chain engagement across the entire range-even under high torque. When paired with compatible Shimano EP801 or EP600 drive units, FREE SHIFT and AUTO SHIFT technologies allow seamless gear changes while coasting or under load, adapting to cadence and terrain automatically. The SW-M9250-IR I-Spec EV shifter provides a compact, ergonomic interface with adjustable positioning for a dialed cockpit. Powered by the DN300 internal battery and charged via the EC300 interface, this kit delivers responsive, quiet, and intuitive electronic shifting for riders chasing peak performance on XC courses and demanding trail rides.