With M8000, Deore XT has adopted the 11 speed configuration of most high end drivetrains. The double configuration has become increasingly popular in the last few years, since it covers most terrain, while eliminating the weight and complication of the third front ring.The premise of the 2x11 configuration is a more than adequate gear ratio spread without the rarely necessary triple in front. The double has been proven to cover almost any terrain that a mountain biker will encounter, although the triple can be an advantage in extreme situations. The Hollowtech II arms have been reshaped with an asymmetric design that's different yet evokes the sophistication of XTR. The right arm is pressed together with the hollow 24mm spindle at the factory, and the splined left crank arm mates to the spindle during installation and is secured with perhaps Shimano's best detail two pinch bolts to secure the arm once the bearing preload is dialed in perfectly. In our experience, it's a superior design in terms of installation, performance, and durability. The bottom bracket is improved, as well, with lighter weight, improved durability, and reduced seal drag.