Letter From Japan

LETTER FROM Japan

ROUNDUP

Honda's antilock brakes

Honda debuted its motorcycle anti-lock brake system to the Japanese press in May. Derived from an English Lucas-Girling design, the all-mechanical Honda system couldn’t be much more different from BMW’s electronic antilock brakes. Even the acronynms have been changed: the Germans prefer ABS for antiblockier system, while Honda insists on the more straightforward ALB for anti-lock brake.

BMW’s ABS depends on electronic sensors and computers to gauge wheel lock, whereas Honda’s design relies on a flywheel inside each wheel hub; indeed, the entire ALB mechanism is incorporated in those hubs, except for one additional hose running from hub to master-cylinder reservoir. This makes it a very easyto-install option on any disc-brake-equipped motorcycle.

The Honda system is inert as long as wheel and flywheel maintain a constant speed ratio. But a locking wheel slows down suddenly, while the flywheel doesn't. This condition causes one valve to close, isolating the master cylinder from the brake system, and maintaining pressure in the line from master cylinder to ALB hub. At the same time, a second valve opens, releasing pressure in the line from ALB hub to brake caliper, therefore reducing braking until the wheel regains speed.

Once the wheel and flywheel speed relationship has recovered, a mechanical pump in the hub steps up the pressure to the brake caliper, increasing braking until: l ) the pressure the rider is applying is matched; or 2) until the wheel locks again, which starts the whole cycle over. In operation, according to Honda, this can happen six to eight times a second, which is as quickly as the BMW system can respond.

But while ALB operation may be complicated to describe, in use it couldn’t be simpler. Grab or stab the brake levers as hard as you can, and the ALB motorcycle stops quickly, with a light pulsing at the brake levers. Locking a wheel is impossible on even an ice-like surface.

Honda demonstrated the system on a CBR1000, but that isn’t necessarily the motorcycle on which ALB will first appear for sale. Honda did say, however, that the system would be displayed in its on-sale form on a motorcycle introduced at the Cologne show in September.

The price? Honda hinted that ALB might be an $800 option in Japan, but that should only be considered a clue.

Honda’s ALB won’t be cheap, but it should be less expensive than BMW’s ABS.

Whether the mechanical or electronic system offers better performance won’t be established until they’re tested side-by-side. But Honda is keeping its options open, and is continuing development on electronic anti-lock systems, as well.

Kengo Yagawa