As widely expected Shimano has launched road disc brakes. Currently the UCI does not allow race-use of disc brakes for road bikes. Shimano is a sponsor of the UCI.
Most bicycles are currently fitted with brakes that achieve deceleration by clamping on the wheel rim. This is 19th Century technology and this method does not work as effectively in the wet. Most other vehicles have been using disc brakes for many years. Disc brakes are also common on mountain bikes. With so many bike companies now producing disc brake systems for road bikes it's only a matter of time before the UCI, the international governing body for cycling, catches up and allows their use in races.
Shimano's BR-R785 hydraulic disc brakes maintain high consistent braking performance regardless the weather conditions through heat management and brake power that can be tuned to riding conditions, terrain, riders’ size and abilities. The hydraulic disc brake kit contains disc brake specific dual control levers, a new 140mm disc rotor and dedicated hubs and wheels.
BR-R785 starts at Ultegra level, one set down from Dura-ace, the top-end groupset used by pro riders. However, the new disc brake system is for Di2 Ultregra, the electronic version. Hydraulic disc brakes have more stopping power and allow riders to brake more efficiently with less energy.
Shimano has equipped its hydraulic disc brakes with mountain bike style Ice technology, a cooling method where the clad rotor blade has a 3 layer-sandwich structure of stainless steel and aluminum, which provides a better radiation performance that reduces the temperature approximately 100 degrees.
Shimano incorporated aluminum fins in the rotor for enhanced heat control. With an increased surface area for heat dispersion, the rotor achieves an additional 50 degrees reduction in heat. The effect of Shimano’s heat management is that the hydraulic disc brakes have no weight restrictions (in normal road usage).
Together with the hydraulic disc brakes Shimano have introduced a compatible wheel set at Ultegra level, WH-RX31. This is an 11-speed centre lock compatible wheel set for road and cyclocross bikes.
The new brake system - which will retail for £599.99 - requires frame disc brake mounts.