BMW was the first to add ABS to motorcycles 23 years ago and continues to be a significant proponent of the technology today (all BMW motorcycles in the US will come standard with ABS in 2012). So, it’s no surprise to see them add ABS to a motorcycle in their Husqvarna division. In this case, however, it’s a world’s first ABS system designed for off-road racing. While not in production, Husqvarna is showing off the technology aboard their current flagship model, the TE 449.
The system used is a so-called dual channel ABS with components supplied by both BMW Motorrad and Husqvarna Motorcycles itself. It consists of two wheel sensors and the associated pulse wheels for detecting the rotational speeds of the front and rear wheels, an ABS pressure modulator, a hydraulic system and an electronic control unit. Due to the particular dynamic requirements of off-road racing, ABS regulation occurs solely at the front wheel. The rear wheel brake is not regulated, so the rider can deliberately lock the rear wheel (a benefit off-road).
Currently, the ABS systems generally used in production motorcycles are only partially suitable for off-road use: their regulation specifications on surfaces such as gravel does not allow for maximum possible brake performance. For this reason, the relevant parameters and in particular the slip thresholds in the Husqvarna Motorcycles Off-Road ABS have been adapted for improved braking performance over rough terrain. Since there is no ABS regulation of the rear wheel, the specifications for road speed and wheel acceleration were also optimized. The additional use of the rear wheel rotational speed supports the reference speed for the front wheel.
In practice, riders with sporty ambitions will benefit from the advantages offered by off-road ABS. It offers significantly increased braking safety and enhanced directional stability. The system allows a rider to concentrate fully on the track while providing less stress and greater comfort. It also allows hobby enduro riders to stretch their personal limits and thereby enjoy even greater off-road fun.
The Husqvarna Motorcycles Off-Road ABS system weighs 1.5 kg (3.3 lbs). When in use, the rider feels a pulse in the handbrake lever providing feedback. The dual channel system also offers potential for further development. For example, it’s possible future version could provide two ABS modes for off-road and on-road use. Activated separately by the rider, the rear-wheel brake could be ABS regulated for traveling on the road.