The road system contains the four constituent components of the hydraulic disc brake system long deployed on mountain bikes: lever, hoses, caliper (with pads) and rotor. For the road system, Shimano’s engineers had to develop an STI lever, rather than one solely responsible for braking. The solution is the ST-R785 dual control lever, a non-series item, engineered to Ultegra level, containing switches to operate compatible electronic derailleurs, and a mineral oil reservoir.
Movement in the lever is controlled with a long-standing Shimano mountain bike technology called a Servo-Wave Mechanism; essentially a roller cam that reduces the required rider input at the lever to actuate the pads. The result? More power for less effort. Shimano claim that much of the development time spent in attaining a ‘feel’ acceptable to road riders in its new STI was spent in this area. While the Servo-Wave Mechanism is non-adjustable, the proximity of pads to rotor, and with it modulation, can be dialled to the rider’s requirement with a facility Shimano call ‘Freestroke’. Adjustment is managed beneath the lever hood with a flat-bladed screwdriver, and controls whether braking is direct or progressive.