Honda Unveils Brake-By-Wire ABS For Sportbikes

Honda Europe recently unveiled the company's latest "Combined ABS" brake system designed specifically for application to sportbikes. A handful of European motojournalists were given the opportunity to try out the prototype on a test course in Germany: a CBR600RR that represents the first production application of this new ABS system, with both the '09 CBR600RR and CBR1000RR available with the system as a $1000 option. This follows the announcement by Honda Motor Company CEO Takeo Fukui-who used to be CEO of HRC, Honda's racing subsidiary-earlier this year that the company plans to install ABS on all its models greater than 250cc by 2010. While some took that to mean that all Hondas will have ABS as standard equipment by that year, it appears that the company will make it available as an option for the time being.

Although conventional antilock brake systems have been available on semi-sporting machinery like Honda's VFR800 for years, actual usage on hard-core sportbikes like the company's CBR series hasn't been practical due to the latter bikes' higher performance capabilities. Because of a sportbike's more demanding braking requirements imposed by the stronger brakes, shorter wheelbase, stiffer suspension and stickier tires, developing an ABS system to work with that higher threshold hasn't been possible until now.

Unlike conventional ABS systems that use a modulator to pulse the brakes and require direct hydraulic pressure generated by the rider, the Combined ABS is a "brake-by-wire" setup that utilizes electric motors to control hydraulic fluid pressure and thus braking power. Sensors measure the brake pressure applied by the rider and feed that information to a central control unit. The electronic control unit then tells two electric motors (one for the front and one for the rear) exactly how much hydraulic fluid pressure/braking power to apply. Because the electric motors precisely control hydraulic pressure to the calipers, no pressure-control valve or modulator is necessary when a wheel is nearing lockup and the ABS is activated; the hydraulic pressure is controlled quickly and accurately enough to negate any need for inline-pressure intervention.

This also means that the transition to ABS intervention is much more seamless. With no pressure-control valve in the system, there are no drastic fluctuations in hydraulic pressure to cause the pulsing at the lever and juddering feel at the wheels that are common to more primitive ABS systems.

Before you get all worked up and wonder how the brakes will work if the engine is off or if there is some sort of electronic-system failure, know this: The Combined ABS is basically inline with the brake system. A valve separates the Combined ABS from the rider-activated portion of the braking system. When the engine is off or there is some sort of electronic failure, the valve is open and the rider controls hydraulic fluid pressure from the front- and rear-brake master cylinders in a normal fashion. Once the engine is running and the bike begins traveling over 3 mph, the valve closes and hydraulic pressure control is turned over to the Combined ABS components.

If you're wondering whether the brake-by-wire system can replicate conventional brake response and performance, the Euro journos all reported that the Combined ABS brake system's power and response was exactly like the stock bike's and that they couldn't tell any difference. The ABS threshold was very high and didn't intervene during heavy braking until it was obvious the edge of normal control was being reached.

Because the system measures both front and rear wheel speeds, the Combined ABS goes another step further than the current LBS (Linked Braking System) used on some Hondas that activates both front and rear brakes when one or the other is applied. The LBS is a mechanical system that requires linking both braking systems together hydraulically, and the system is limited to a fixed ratio of front/rear-brake power distribution. The Combined ABS is two separate braking systems controlled by a central unit, so it is able to continuously and infinitely vary the braking power to each wheel, allowing it to adapt to the CBR's more demanding handling characteristics. All the Europeans who rode the Combined ABS CBR said that the system worked well, offering the same braking traits as the current LBS, even with the CBR's less effective rear brake (due to its greater weight transfer during braking).

Although we're still not fans of the LBS, we're definitely interested in the Combined ABS system. When one becomes available for testing, you can bet we'll be right on it to give you the full scoop.