SHIMANO XTR M9100 12 SPEED REAR DERAILLEURElegantly designed, the XTR M9100 Rear Derailleur is suitable for use with Shimano's 12-Speed drivetrain system and comes equipped with oversized 13T pulley wheels and an updated Shadow RD+ mechanism which is narrower and more discrete to outfox the flow-killing risks of hard-riding mountain biking. Aluminium-made, this compact and convenient derailleur belies its size to give hugely impressive performance.