Rider-Aid Revolution

Electronic rider-assist systems: do these live up to the hype?

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Never before have we witnessed such a vast array of electronic rider-assist systems as featured on this current crop of liter-class sportbikes. From selectable power-delivery profiles, traction control, anti-lock brakes or electronically controlled steering dampers, innovation is the order of the day. Is this trend marketing hype or do these modern marvels live up to their promise of enhanced traction, safety and control at speed?

Unless you’ve just recently returned from deep space exploration, you should already be somewhat familiar with the various iterations of rider-selectable power-delivery modes as found on the Aprilia RSV4, BMW S1000RR and Yamaha YZF-R1. These machines all feature throttle-by-wire fuel injection and give the bike’s ECU final authority over throttle-plate operation, thus allowing the design engineers to create different throttle-response maps to offer different modes for track and street use. Selecting Rain mode on the Aprilia and BMW or Yamaha’s C mode not only dramatically softens response but also limits throttle opening, resulting in reduced peak output to make these potent performers more manageable in slick conditions.

BMW took a step farther and has followed Ducati’s lead with a fully functional race-developed traction-control system. Both bikes allow the option of toggling off TC or setting the degree of intervention to suit the current conditions. Ducati’s setup is more straightforward, offering eight levels of TC sensitivity, selectable only while the bike is stationary. The system seamlessly retards ignition advance when subtle rear-wheel spin is detected and will also trim fuel when needed. On-track at Miller Motorsports Park, we found Level 3 allowed subtle drifts while keeping drive-sapping wheelspin in check and never feeling intrusive. Level 5 proved well-suited to both dry/wet roads encountered during our street ride.

BMW’s Dynamic Traction Control permits on-the-fly selection among its four modes (Rain, Sport, Race and Slick), making it easy to compare each back-to-back on the track, but it can be a bit daunting to get a handle on what’s going on because of the system’s added elements. BMW’s strategy utilizes a combination of ignition-timing retard and throttle override, utilizing its throttle-by-wire control to notch back power as needed to maintain grip. The unique aspect of this setup is the use of an underseat gyro that monitors cornering lean angle. DTC processes this data and restricts acceleration (via the ECU throttle override) when the bike is banked over beyond a mode-specific lean angle threshold of 38, 45, 48 or 53 degrees.

For further exploration of just how the BMW systems works, we headed to Willow Springs Raceway and attacked Turn 2 in particular, a very long, constant-radius uphill curve that provided good insight as to the finer workings of DTC’s lean-angle threshold. The test consisted of running in hard and exceeding Sport mode’s 45-degree lean threshold with the throttle fully closed. What I found is that even when beyond the lean threshold, the system does permit a modest amount of throttle input to enable the rider to balance the chassis and tire load in the traditional fashion. A rather disturbing observation came to light while rounding a couple of the track’s more positive-cambered corners. Since the gyro-determined lean angle references the horizon rather than the road, banked corners can throw DTC a curve ball and result in reluctant acceleration even when grip is solid.

Ducati gets our vote for its more functionally seamless, less-intrusive traction control.

Our next stop involved back-to-back brake testing between the ABS-equipped BMW and Honda CBR1000RR. While the BMW emerged as the clear winner with an astounding 112-foot stop from 60 mph compared with a Honda best of 125 feet, if points were deducted for Pucker Factor it would be a much closer contest. Honda’s Combined ABS is more focused on maintaining chassis stability under hard braking, while the BMW’s Race ABS aggressively goes after the shortest stop possible, and does so in dramatic fashion.

When set to Rain or Sport mode, the BMW system detects rear-wheel lift-off and will quickly cycle front-brake pressure to keep the rear from lifting farther. During our testing, these more-intrusive modes were within a couple feet of the nose-wheelie-prone Race and Slick modes. Grippy tire, quality fork, short wheelbase and software programming to straddle the picket fence of maximum grip all add up to one wild ride of tire-howling, multiple-nose-wheelie antics unlike anything I’ve experienced. But you can’t argue with the results or ignore that BMW’s Race ABS weighs 20 pounds less than Honda’s C-ABS system.

The buck stops on a dime aboard the Beemer for now, but it is safe to say this is just the beginning of the superbike rider-aid revolution. The Italians and Germans have opened the gate; now, we look for the Big Four’s corporate lawyers to get out of the way and allow sportbike evolution by the Japanese.