"The new one-piece XTR brake calliper (BR-M985) boasts an oversize ceramic piston that is lighter, stiffer and insulates the system from heat better than its predecessor. Maintenance should be easier and quicker thanks to one-way bleeding and improved oil routing, and there's a more powerful Saint-style brake hose, plus its alloy banjo means it should fit a wide variety of frames.
The big change, however, is that under Shimano's new Rider Tuned Technology system you now have a choice of two swanky looking new levers: a super-lightweight pair designed for cross-country racing (BL-M985) or a more powerful and better modulated set aimed at trail riders (BL-M988).
The cross-country option is said to be 40g lighter than current XTR M975, yet 10 percent more powerful. It comes with a choice of resin pads with alloy back plates, or metal pads with titanium back plates. Claimed weight is 215g front / 229g rear (including calliper).
However, if you prize power over gram saving, you can instead team the new compact calliper up with the more robust lever, which features a new short-stroke version of Shimano's Servo-Wave leverage change cam. This brakeset comes with Shimano's new Ice Technologies brake pads, which use finned extensions to pull heat away from the calliper, fluid and rotor.
The trail brakeset also gets slightly wider levers (14mm, compared to 13mm) with a reach-adjust dial. The result of all this is a claimed 25 percent increase in braking power over M975, with no increase in weight. Claimed weight is 247g front / 261g rear.
Both systems get the new Ice Tech rotor, which sandwiches an aluminium core between stainless steel outer layers for improved heat dissipation. This is said to reduce brake fade on long downhills by 65 percent and double pad life, as well as cutting noise and weight. Four sizes are available – 140, 160, 180 and 203mm – with Center Lock mountings only. Claimed weight is 126g (160mm) thanks to use of an aluminium spider. The new discs can be used with any Shimano brake.
Features of both brakesets include:
- Integrated barrel reservoir lever design
- Split clamp for quick installation and removal
- Two-finger lever with ergo pivot and anti-slip dimples
- Clean bleeding by funnel
- Can be used with I-Spec integrated brake/shifter clamp to save weight and free up handlebar space"