The Shimano Di2 XTR M9250 wireless long cage derailleur paired with a standard 10-51t M9200 cassette (cassette sold separately) gives riders and racers the speed range and robustness to tackle every trail on the mountain. With built-in Automatic Crash Recovery an impact-deflecting shape and simple covered-pulley solutions this derailleur stands up to harsh trail impacts and still retains its lightning-quick shifting speed and top-level performance