When we're outfitting our dream race bike, we opt for the best when it comes to mechanical shifting. Shimano's M9000 XTR Rear Derailleur is the top-of-the-line offering for Shimano's 11-speed mountain bike drivetrains. It's capable of handling cogs up to 46 teeth, and can be set up in 1 x 11, 2 x 11, and 3 x 11 configurations. Compared to the previous generation, Shimano altered the parallelogram of the derailleur a bit for more stable shifting, and also moved the top pulley wheel to allow for greater capacity without resorting to bottoming out the B-screw.