Honda's Magic Gearbox: Worth A Few Hundredths A Shift
Honda's seamless shift gearbox has been the talk of the MotoGP world since it first debuted at Sepang, with journalists on a quest to chase down exactly what it is and how it works. The only response you receive from HRC or Honda riders about the gearbox is that it is "better" and that it is "smoother". The best guess about its operation so far has been that it is either based on or very similar to the Xtrac Instantaneous Gearshift System, which allows two gears to be engaged simultaneously, while driving only one.
Since the introduction of the system, speculation has been rampant as to exactly how much advantage Honda's gearbox confers. Wild guesses were doing the rounds, with the highest guess being that it would give an advantage of 0.9 seconds a lap, an absolute eternity. According to one of the journalists over at GPOne.com, Filippo Preziosi said he believed that Honda's gearbox was probably worth around 0.2 seconds a lap.
In my adopted home of the Netherlands, they have a saying: "Meten is weten", to measure is to know. In that spirit, I went out to the side of the track during the test, and took a number of recordings of bikes exiting Turn 10 and shifting up the gears, going past and shifting up. On the basis of those sound recordings, I tried to estimate the length of the gearchange for each of the bikes that I had recorded.
The methodology was as follows: taking a couple of gearchanges from each sound file, I tried to identify the start and end for each gearchange. By looking at the length of the sound sample left, I estimated the duration of the sample, and therefore the gearchange. Here are the timings I found:
|Bike||Average shift time (ms)|
The timings taken are by their very nature approximate, given that the sounds were recorded on a simple Olympus voice recorder, and estimation of gearshift duration was done by trying to match sound to the waveform. However, several clear differences stand out. Below are screenshots of the sound files I recorded.
The above file is the Ducati, and the shift point is immediately clear, the gap between the peaks as the gear is shifted. The Ducati appears to take the longest time to shift, as it has the largest gap between the power being switched on and off. When asked, Casey Stoner confirmed that the Ducati was a lot harder to change gears on, saying that that was one of the things that had most surprised him when he first joined Ducati back in 2007.
Next is the Yamaha, and what you see most clearly in the Yamaha gearshift is the pop as the quickshifter is enaged. That huge spike in the middle is the explosion caused when the unburned fuel from cutting the spark by the quickshifter catches fire, and Yamahas can always be identified by that loud bang. The shift itself is shorter than the Ducati, but the estimate is hardest to make because of that giant bang in the middle.
And finally, the Honda. The gear change sounds silky smooth just to the ear, but looking at it closer makes it even more remarkable. I have highlighted the spot where the gear changes, and what is most striking about the graph is it seems to take about the same time as a single cylinder firing from Honda's V4. Without knowing the exact engine firing order, V angle and firing timing (and good luck getting that data), it is hard to estimate just how quickly that is, but looking at the average timing, it is a clear advantage.
The real advantage has been repeated by all three of Repsol's riders when talking to the press. The bike stays much more stable when changing up through the gears while leaned hard over. That is visible on the track: the bike stays perfectly flat as Casey Stoner, Dani Pedrosa and Andrea Dovizioso power through the corners. Yamaha are already working on a system of their own to counter the Hondas, and looking at the time gains, it looks to be a very wise investment.