Tech: How ABS has saved us all, and ruined some bikes on track
Grabbing a fistful while kneedown and not crashing... how does that work?
Cornering ABS is a confusing technology to get your head around. The system, which is now creeping into cheaper bikes like KTM’s new 790 Duke, allows you to brake as hard as possible while leant over without instantly tucking the front. Here’s how this remarkable development in motorcycle safety works.
“To understand cornering ABS you need to understand the dependency between grip and brake pressure, which is called the circle of traction,” explains Gerald Matschl, KTM VP for R&D. “The horizontal axis is the front wheel’s grip with the vertical acceleration and deceleration. Around these axes is a circle and as long as you remain within it, you are safe. However stray outside the circle and you will lose front wheel traction and crash. Cornering ABS ensures the relationship between grip and braking remains within the circle.” So how does cornering ABS keep you within these parameters? The IMU (inertial Measurement Unit) knows the bike’s lean angle and, when you brake, the system measures brake pressure and lean angle and applies a pre-set algorithm. If it computes that the brake pressure at that lean angle is outside the ‘circle of traction’ it reduces the braking force to prevent losing traction. If the ABS is activated by the tyre slipping then the system will also react almost instantly.
‘Cornering ABS is simply mind-blowing’
But there’s more, too. When you brake while lent over, a bike’s natural reaction is to stand up. When this happens the system senses lean has reduced and applies more brake pressure. So, if you hold onto the brake you’ll stop as fast as physically possible. “Cornering ABS is very complicated to build an algorithm for,” says Matschl. “However we can use the same basic algorithm on various models to reduce development costs and expand its use to more price-sensitive bikes in the future, something we have started with the 790 Duke.”
So... does it work?
Grabbing the front brake as hard as possible at over 40mph while your knee is on the ground takes a lot of trust in a system but that’s exactly what I did at KTM’s test track – and I didn’t crash. Cornering ABS is, quite simply, mind-blowing.
Most front-end crashes happen at that initial panic input of brake. You see the danger, grab the lever too hard and the front instantly washes out. Replicate this action with cornering ABS and you feel a pulse from the brake lever, the bike stands up and if you keep hold of the brake lever you stop in an incredibly short distance. The sooner it is made available on a wider range of bikes, which will happen when costs inevitably reduce as they have with standard ABS, the better.