Notably, the revamped group includes a Shadow Plus rear derailleur, which uses a one-way clutch to reduce dropped chains eliminate chainslap. Other additions include a 2x10 Dyna-Sys crankset, a front hub with a 15mm thru-axle, direct-mount front derailleurs, and I-Spec brackets that streamline the interface between the shifter and brake lever. The brakes also come with heat-reducing Ice-Tech rotors that were first developed for Shimano’s flagship XTR group. The steel rotors have an aluminum core, which better absorbs heat and prevents the outer edges from getting too hot during intensive braking—a problem that can lead to loss of power.
In addition to redesigning Deore, Shimano engineers also developed several new 27.5-inch and 29er wheels. Most notable are the XT-level WH-M785 hoops, which will be available in a 27.5 size. A new mid-level wheel, the MT35, also comes in a 27.5 option. Shimano also unveiled the less expensive WH-MT15, which comes in 26-inch and 29er sizes.
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