G2X DATA ACQUISITION
Midway through the second day of festivities at Chuckwalla Valley Raceway, we strapped our Racepak G2X data acquisition system to each bike as Bradley turned a couple of laps in a Superpole-style showdown. Everything was proceeding swimmingly in alphabetical order until we got to the Ks, and Bradley crashed the Kawasaki on his second timed lap. Unfortunately he was a bit too banged up to continue, so we only have lap times and data for five of the eight bikes — the Aprilia, BMW, Ducati, Honda and the Kawasaki.
Chuckwalla is a 2.68-mile, 17-turn track located approximately 50 miles east of Palm Springs in the Coachella Valley, with approximately 25 feet in elevation changes. The track can be ridden in either direction; we ran counterclockwise for both days. The map included here shows our own corner numbers, along with some of the pertinent speeds and segment times. We also included each bike’s relative location at several points on the course. The graph shows speed for each bike over the course of a lap, plotted against distance.
A spread of 1.66 seconds separates the fastest bike (the ZX-10R) and the slowest (the 1199 Panigale), with the other three bikes fairly evenly distributed between those two. A look at the speeds, segment times and lap-time difference data (not shown here) indicates that no one bike stands out as being significantly better than the others in any one particular area - the segment times and speeds all fall in an approximately similar order to the lap times. Still, there are some interesting points to consider.
From the speeds on the straights, it’s clear that the BMW and the Kawasaki are the fastest bikes in a straight line, and this is partly explains how the two bikes logged the two quickest lap times. However, those speeds are the result of very different characteristics. The S 1000 RR is fast through brute horsepower and typically has higher acceleration numbers on each straight, whereas segment data shows the ZX-10R has better exit speed from each corner. Even though the BMW is more powerful, the straights at Chuckwalla are not long enough for it to overcome the corner-exit deficit. Notably, the Honda matches and even exceeds the Kawasaki’s corner and corner exit speeds in many instances, yet lacks the top-end power to keep pace with either the ZX-10R or the S 1000 RR on the following straights.
In the braking zones at the end of the two main straights, the Aprilia shows the most deceleration, logging a peak of 1.1 g at the end of the back straight. Looking at combinations of deceleration and lateral g (trail-braking), it’s the Aprilia again that logs the highest peak number, with Bradley braking at .75 g while cornering at .75 g arcing into turn 2 — that is braking at about 70 percent of maximum while leaned over to at least 40 degrees). While these numbers reflect the RSV’s excellent brakes and front-end feel, braking data later in the lap does not show a clear advantage in these characteristics for the Aprilia.
The two chicanes at Chuckwalla, labeled here as turns 5 and 6, are both uphill in the counterclockwise direction. The BMW has the quickest segment time through the first, yet is almost the slowest through the second. Bradley felt that he went through the chicanes equally quickly on each bike, yet there were significant differences in performance. For example, the Ducati’s light weight helped it steer quickly, but it was unstable in the transitions. The Aprilia felt heavier through the transitions, yet that was offset by better front-end feel. And the BMW steered heavy but its stiff chassis allowed Bradley to be aggressive with little consequence.
Two sections of the track stress accelerating and braking while leaned over. The first is turns 2 and 3, two high-speed right-hand corners fairly close together. Between the two, the bike is lifted from maximum lean to approximately 25 degrees for a brief spell of acceleration and braking before being leaned into turn 3. Likewise, turn 9 is actually two left-hand corners quite close. The Honda and Kawasaki logged the quickest segment times in these sections; the ZX-10R’s stable chassis and excellent traction control help it log the fastest speed in the short straight between turns 2 and 3 — and the most exit speed — while the Honda was not far behind thanks to its strong midrange. In turn 9 alone, the ZX-10R gains a tenth of a second on the BMW; with its traction control turned off for the timed laps, these small bursts of power proved difficult on the S 1000 RR.
Turn 8 on our track map is actually two turns close together, with a decreasing-radius, downhill line that requires a long period of time at partial throttle. The BMW’s solid chassis excels here, and it gains a full tenth of a second on the Kawasaki. The Aprilia is also quicker than the ZX-10R, due to solid front-end feel and composure. Bradley did note that this corner in particular caused trouble for the Honda, as the soft rear suspension unloaded the front end excessively; the CBR loses a quarter second to the BMW here.
Bridgestone R10 DOT Racing Tires
For the track portion of this year’s literbike testing, seven of the eight bikes were shod with Bridgestone’s relatively new R10 DOT race tire. The eighth bike, Ducati’s 1199 Panigale, rolled on its OE Pirelli Diablo Supercorsa SP rubber for both the track and street testing, the Italian manufacturer noting that its DTC (Ducati Traction Control) system would work more effectively with the bike sporting the OE 200/55-size tire.
Introduced just a year ago, Bridgestone’s R10 race tire features a reworked tread pattern in addition to a more heavily crowned profile that’s aimed to improve turn-in characteristics. 3D grooves near the midsection of the tire are intended to provide better braking performance up front and improved grip out back, while vertical grooves further inward are designed to enhance steering traits at small lean angles.
We personally were introduced to the R10 during the 2011 600cc comparison at the Streets of Willow. With each of our 2012 literbike contestants having anywhere from 40-70 horsepower more than even the strongest 600, we presumed the Bridgestone’s would react much differently this time around. But much to our surprise, the same traits we found accommodating in last year’s test trickled over to this year’s. What impressed us most about the R10 is its steering characteristics into the corner; pick a line and the tire really helps you get there. Grip from both the front and rear is impressive, as are the wear characteristics. Multiple bikes went a full day without a tire change, for instance, and the R10s provided a high level of grip even as the laps continued to click off; this all despite temperatures that ranged from 100-107 degrees.
When the tires did heat up and break loose, they did so in a very predictable manner, without letting go immediately and spitting us out of the saddle. And as a whole, the R10 feels very composed at a brisk pace, with zero squirm on the brakes and little tire flex out of the corner. We were wishing for a little more front tire feedback at times, but nothing alarming.
The R10 DOT race tire is currently available in a 120/70ZR-17 size and Type 3 (medium) compound. There are a few more options out back; the R10 rears are offered in a 180/55ZR-17 and 190/55ZR-17 size, in both a Type 2 (hard) and Type 3 (medium) compounds. For more info, and to find your local race tire vendor, log onto www.bridgestonemotorcycletires.com.
Chicken Hawk Racing Tire Warmers
Chicken Hawk Racing’s new-for-2012 tire warmers kept our Bridgestone R10 race tires company for the duration of our two days at Chuckwalla Raceway — as if the 100-plus degree temperatures weren’t enough to keep things hot. Designed to bring tire temps up fast and effectively, CHR’s latest bun warmers feature neoprene side panels that better insulate the tire and block the wind from blowing across the wheel.
Similar to its predecessor, the updated tire warmer uses a red/green operating light to indicate whether the warmer is heating or at a proper operating temperature. Kevlar insulation helps the warmers retain heat, and a melt-proof inner liner ensures you won’t return to your pits with a smoking surprise. Added features like the high-impact temperature controllers and full-coverage heating elements further enhance durability and safety.
Installing and removing the CHR tire warmers proved to be a cinch at the racetrack, and we found the overall construction of the product to be top-notch. With the tires pre-heated to 175 degrees, we also felt more confident rolling out onto the track, with more grip and less tire squirm during the warm-up lap. For more info regarding Chicken Hawk Racing’s new $425 tire warmer, or to place an order, visit www.chickenhawkracing.com.