ABS Overview

ABS brakes on a BMW motorcycle.

In 1988 BMW introduced the first motorcycle with an electronic-hydraulic ABS system—the BMW K100. Honda followed suit in 1992 with the launch of its first motorcycle ABS system on the ST1100 Pan European. In 1997 Suzuki launched its GSF1200SA (Bandit) with ABS. In 2005, Harley-Davidson began offering ABS as an option for Police Bikes, and in 2009, it became standard on the Harley Ultra-Glide touring motorcycle.

Operation

The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).

A typical ABS is composed of a central electronic control unit (ECU), wheel speed sensors — one for each wheel — and two or more hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel, and when it detects a wheel rotating significantly slower than the others — a condition indicative of impending wheel lock — it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel. The wheel then turns faster; when the ECU detects it is turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied and the wheel slows. This process is repeated continuously, and can be detected by the driver via brake pulsation. A typical anti-lock system can apply and release braking pressure up to 20 times a second.

If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is rectified.

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