Conventional ABS has improved steadily since the first systems of the 1980s. The latest versions are very impressive, but even the best are triggered only by wheel speed—they can’t anticipate variations in grip through lean angle or vehicle attitude, which means they can’t cope with more than a fairly modest angle of lean.
That’s set to change. Bosch’s new system, called Motorcycle Stability Control and debuting on the new KTM 1190 Adventure, adds a fresh wrinkle to ABS: the lean-angle sensor. This device is about the size and weight of a wristwatch that consumes less than a tenth of an amp of power and can relay information about a bike’s pitch and lean angles 200 times per second.
For the MSC development, Bosch’s team, based in Japan and Germany, combined the lean-angle sensor with the firm’s latest ABS 9M unit. This team spent 18 months developing algorithms and testing. One engineer purposely crashed a bike fitted with conventional ABS, but Bosch insists that none of its riders crashed while using MSC.
MSC uses an array of sensors in addition to the lean-angle gadget to register the bike’s motion. Wheel sensors measure the rotational speed of front and rear wheels, and the lean-angle sensor computes lean and pitch every five milliseconds. Based on this information, plus known parameters including tire size, tire shape, and sensor location, the ABS control unit calculates the physical limits of brake force on the basis of lean angle.
A control module (left) and lean-angle sensor (right) combine forces to create Bosch’s Mot
If the MSC recognizes that a wheel is starting to lock, the ABS control unit activates the pressure modulator in the brake circuit. This lowers the brake pressure and builds it up again within a fraction of a second, with the result that the correct amount of brake pressure is applied to prevent each wheel from locking. The system links front and rear brakes and is also designed to give an ideal distribution of front/rear braking. The addition of the lean-angle sensor means the system knows in advance how much brake force the tires are likely to tolerate before an actual lockup occurs. As such, when a lockup does happen, it’s much closer to threshold braking than a full-on panic stop. And as a result of that, the ABS can react less aggressively to eliminate lockup.
The technical explanations and videos were convincing, but I was still slightly nervous as the gathered journalists approached the first test session at Bosch’s Boxberg proving ground near Frankfurt. We were shown a patch of polished cobbles and told to ride round and brake as hard as we liked while leaning over. Although the low-friction surface meant speeds would be low and cornering angles not great, I made sure to ride counterclockwise, so hopefully a spill wouldn’t damage my recently operated-on right shoulder.
But I didn’t crash—however hard I tried. It was a weird feeling to grab a handful of front anchor while leaned over on such a slippery surface, feel the front end twitch, and continue riding instead of hitting the ground. A few times there was enough of a twitch that I momentarily thought I was crashing, but the system saved me every time.
It was just as mind-blowing to move over to the pavement area and brake hard at pretty much full lean, while following a semi-circular pattern of cones. And then to move to another area where I followed Bosch engineer Christian Gröger, riding round in a series of three circles of increasing radius, repeatedly jabbing the front or rear brake.
The key to never crashing on the brakes again? It’s all right here under the seat, where t
The biggest circle was the best because when squeezing the front brake lever while cranked over at 60 mph, I not only felt the bars twitch but heard the front Conti squeak, yet the MSC system released the brake quickly enough to prevent a crash. After a dozen or so laps and another 50 or so certain crashes prevented, I came in and was buzzing for hours afterward. I really could hardly believe what I’d just experienced.
One bonus of MSC is that it doesn’t require hardware in addition to that used by the KTM’s ABS and traction control. It does, however, need a considerable amount of testing and fine-tuning, which is why KTM is rolling out the technology gradually, starting with the Adventure and Adventure R models—it’s standard on all 2014 models and available as a software upgrade to Adventures sold in Europe as 2013s. The 1290 Super Duke R will eventually get the technology as well.