TRACTION CONTROL – WHAT IT’S ALL ABOUT, HOW IT WORKS, AND WHY YOUWANT IT!
How it works, when it’s needed, and is it killing our skills?
Is there any motorcycle innovation that’s split opinion to the level traction-control has over recent years? Likely not, and with TC it’s often a case of the ‘have-nots’ giving the ‘haves’ grief for using rider aids. There’s little understanding of them if someone has never tried them (a good system, at least), and those that do are soon converted to the new-age technology. But never mind all that for the moment, let’s look at TC, what it is, how it works and where it comes from first, eh?
Simple TC
Traction-control systems reduce power when their sensors detect the rear wheel has already begun to lose traction. Basic road bike systems monitor the ABS sensors mounted on the wheels and if they sense that the rear wheel is accelerating faster than the front, the bike’s engine control unit is instructed to retard or cut the ignition. In addition, the throttle butterflies can be quickly closed on ride-by-wire equipped bikes. The traction-control system also needs information from other areas to be able to work effectively.
In addition to awareness of throttle position and engine revs, knowledge of what gear the bike is in will allow even a simple system to calculate if the bike is wheelieing, or not. In the unlikely event of simultaneous wheelspin and wheelie, TC systems can fall back on less accurate pre-programmed parameters of probable tyre traction values, plus the bike’s inertia and rear wheel’s angular inertia. The TC system will then make assumptions on how fast the rear tyre can be allowed to accelerate and still maintain traction.
Dynamic TC
More advanced dynamic TC systems really take the concept to the next level. Although they still use the feedback from ABS sensors and compare front and rear wheel speed, they also utilise a whole host of other sensors, measuring far more than just what the wheels and the engine are doing. The most significant technological leap forward has been thanks to Inertial Measurement Units (IMU).
IMUs continually and minutely measuring the whole attitude of the bike. They allow TC systems to monitor data like the bike’s acceleration, or deceleration, if it is going up or downhill, how bumpy the road is, how far over it is leant and even how much cornering force the bike is generating. Once analysed and processed through the dynamic TC system’s brain, all this data facilitates the minute control of the engine’s power delivery and tailors the output to the current situation.
Intruder alert
One of the main complaints of early TC and even some modern basic systems is the intrusive way in which they reign-in wheel spin. This is because some work reactively. They are only able to reduce or stop a spin-up once it’s happened, so even a well calibrated passive system like this is going to make its presence felt to the rider as power delivery is artificially cut.
Their lack of sophistication also requires a good margin of safety with the level of wheel spin, or tyre slip-angle, that is deemed allowable. Passive systems must cut-in early, otherwise the large reduction in power delivery needed to regain traction from a big spin-up will destabilise the bike. Much