G2X Data Acquisition
With Bradley once again riding for official lap times, we kept an eye on each bike’s (and Bradley’s) progress using our Racepak G2X data acquisition system. The GPS-based Racepak is capable of monitoring speed and acceleration forces, and can even show differences in cornering lines between the bikes. The map shown here includes segment times for some of the Streets of Willow’s more technical sections, as well as each bike’s relative location at several points on the course. The graph plots speed over the course of each bike’s best lap.
Even though we are constantly amazed at how closely matched the middleweights are on the racetrack, this year’s class is the tightest we’ve encountered yet: Less than a quarter second separates the fastest (the Triumph) from the slowest (the Suzuki) lap time at the Streets of Willow, or about the time it would take for the five bikes to cross the start/finish line nose-to-tail. The segment times for the tricky turns 1 and 2 show part of the story. The Triumph carries more speed through turn 1 and cuts a tighter line through turn 2 than the other bikes, partially thanks to the R model’s solid front fork and potent Brembo brakes. In this section alone the Triumph gains .3 seconds on the other bikes, which all make it through within .05 seconds of each other. From there until the final turns on the track, the segment times for all five bikes are virtually identical. Note, however, the segment times for the turn 10-12 portion of the lap—here the Triumph gives back that .3 seconds and even more to some of the bikes. The data shows Bradley entering turn 10 with quite a head of steam compared with the others, but this time he can’t make the corner and runs wide—enough so that it’s obvious to see on the track mapping software (not shown here). The Triumph and Bradley recover just enough time in the last segments to edge the Yamaha and Kawasaki for quickest lap time.
The sector times for all five bikes are almost identical through the turn 4 to turn 8 esses section, even though speeds vary considerably. It’s worth noting here that the speed graph shows just one part of the equation, the other part being distance. If one bike is able to carve a tighter line than another, it can go slower through the section but make it through in less time by virtue of simply not traveling as far. That looks to be the case with the ZX-6R, which posts the slowest average speed through this section (which is noticeable on the speed graph) yet one of the quicker segment times. The lithe Kawasaki likewise posts the quickest segment time for the second set of esses on the track, turns 10 through 12.
The top speeds reached on the back straight show the Kawasaki as fastest, and this is consistent with other data over the course of the lap. The ZX-6R shows higher acceleration numbers exiting most corners than the other bikes and it keeps that advantage down the straights. The Honda and Yamaha show similar acceleration values exiting many corners, but whereas the Honda backs that up with the second-highest trap speed the Yamaha does not appear to accelerate as well in the higher gears. Most corners on the Streets of Willow are taken in second gear, working to the R6’s advantage, but the story may be different at a faster track.
While the Triumph does show high braking forces entering turn 2 (where it gained time) and turn 10 (where it lost time), it’s the lightweight Honda that logged consistently harder braking into most turns. The Honda and Yamaha show slightly higher combinations of cornering and braking forces—better trail braking—than the other bikes entering most turns, although again the Triumph data shows the highest absolute trail-braking numbers during Bradley’s banzai entry into turn 2.
We lowered the footpegs on...
We lowered the footpegs on the Suzuki for a bit more legroom, preferring that on both the street and track. Even in the lower position, as shown here, the seat/peg distance is just as tight as the other bikes. The Honda has the most upright riding position, while most of our testers thought the Triumph's ergo were the least friendly; the Kawasaki's strike a nice compromise.
Note how the R6 (blue line)...
Note how the R6 (blue line) has a thrust advantage in the upper midrange portion of its powerband, especially in second gear. This allowed it to really charge off the corners at the Streets of Willow. Note also how the Triumph’s torque allows it to get a jump, but then the quicker-revving four-cylinders soon surpass it from the midrange to top-end rpm.
The Suzuki’s midrange and...
The Suzuki’s midrange and light weight puts the hurt on the others in the 60-80 mph roll-ons, although its top-end deficit shows in the 80-100 mph numbers. Despite its torque advantage, the Triumph’s comparatively slow-revving triple gets eaten up in the 80-100 mph roll-on by all but the R6.
The Kawasaki’s strong, quick-revving...
The Kawasaki’s strong, quick-revving engine gets the jump on everyone off the line and carries that advantage down the rest of the strip. The Triumph’s tall first gear and relatively slow-revving three allows the GSX-R’s strong midrange to out-accelerate the more powerful Triumph.
Triumph has a surplus of power at all portions of its powerband compared to the others, but at the track, its shorter spread relative to the four-cylinders enforces more shifting per lap. The Suzuki’s excellent partial-throttle response and midrange acceleration can’t be graphically displayed on a dyno chart.