ABS Tech

Anti-lock braking systems have been offered for many years on various touring and sport-touring motorcycles, but only recently has ABS been available on sportbikes. Previous systems have had limited performance on twisty roads or the racetrack, in addition to adding a significant weight penalty. The three systems tested here, however, have performance and safety benefits applicable to a sportbike, with two of the systems adding a minimal weight penalty. A basic system consists of wheel speed sensors to measure individual wheel speeds, hydraulic pumps to control braking pressure at each wheel, and an ECU to manage the system. When the system detects a wheel slowing too quickly, or one wheel slowing significantly more than the other, hydraulic pressure to that wheel’s brake is reduced, allowing the wheel to return to an appropriate speed.

Both the BMW S 1000 RR and Kawasaki ZX-10R use versions of the Bosch Generation 9 motorcycle-specific ABS, which combines the pump and control unit in a single, lightweight unit. The system’s Plus variant, as used in the ZX-10R’s KIBS, uses an additional pressure sensor within the unit, which, according to Bosch, “takes effect even when pressure is being built up during emergency braking. This specifically prevents the rear wheel rising.” As opposed to the version used on Kawasaki’s Concours that works only when the bike is close to vertical, KIBS operates even when the bike is leaning. The system monitors wheel speed, caliper pressure, engine rpm, throttle position, clutch actuation and gear position. This information is provided to the KIBS ECU every five milliseconds, a significantly higher sampling rate than the Concours’ setup, and the engine data gives the system increased brake control during downshifts. According to Kawasaki, KIBS is capable of predicting slip and modulating brake pressure as opposed to a simple on/off operation, making it suitable for sportbike use. On the ZX-10R, KIBS adds seven pounds of weight.

The S 1000 RR utilizes the Enhanced version of the Bosch Generation 9 ABS, which adds integrated braking. On the BMW, the front brake lever works both front and rear brakes, while the rear brake pedal works only the rear brake. Additionally, a “very elaborate rear-wheel lift-off detector” is capable of discerning the difference between a bump in the road and rear-wheel lockup. The Race ABS setup is combined with the bike’s traction control, and changes its operation in the various riding modes. In Rain and Sport modes, the ABS “intervenes early enough to prevent the wheels from locking and the rear wheel from lifting off the ground.” In Race mode, ABS intervenes later but still prevents the wheels from locking; the rear-wheel lift detection is deactivated and the rear wheel is allowed to come off the ground. Slick mode is identical to Race, but ABS on the rear wheel is deactivated, allowing the wheel to lock when the foot pedal is depressed and the rider to skid into a corner. While we haven’t tested a non-ABS S 1000 RR to date, BMW claims the Race ABS system adds 5.5 pounds to the bike.

Honda’s Combined ABS is a patented system designed for sportbike use that is more electronic braking than simply ABS. The system’s objective, according to Honda, is to combine the front and rear brakes to reduce the stopping distances that result from using more of one than the other. As such, the front lever works both brakes, as does the rear pedal; however, the rear brake pedal only works the front brake when rear wheel lockup is sensed. This allows an experienced rider to use the rear brake as normal for sport riding. The C-ABS utilizes two hydraulic sensors; activating either brake generates pressure in the sensors, and the system’s ECU calculates how much braking force to apply using a hydraulic pump for each wheel. The elaborate system allows some advantages compared with conventional ABS. According to Honda, more control over the application and release of the brakes controls pitching of the motorcycle, while the isolation of braking inputs from caliper pressure reduces pulsing at the brake lever. A failsafe function returns control to normal operation in the event of a problem — but the system adds 25 pounds to the CBR’s weight according to our scales.