Tuesday, April 22, 2014

Going Faster

How do you go faster on the race track?

First, we start off with learning how to ride. I mean, really learn how to ride. Going beyond where is the clutch where is the brake. Learning how to look through a corner, how to feel the ground beneath your tires, becoming one with the bike.

Once you have achieved that, what is next?

Learning the track, known its secrets. This takes seat time at that track, it definitely helps to walk the track, several times.

But then what?

For me, the next step is data. For many people, racers, track day enthusiasts, a lap timer tells you one thing, how fast you went around the track each lap. But a modern GPS lap timer gives you so much more. It is this "more" that is far more interesting than just how fast you went around the track.

Recently, I had the opportunity to record a hot lap by three time 450 Superbike champion Dave Moss. Even better, that lap was recorded while he was on one of the 450 "triples" that I currently race.

For this recording I used a QStarz 10Hz GPS Laptimer. 10Hz means that it is recording the position of the bike 10 times every second. Further, this lap timer has an accelerometer which allows it to track acceleration, braking and turning forces. With this information we can track:

* Speed
* Lateral G Force (how hard the bike is turning)
* Acceleration
* Deceleration
* Line around the track

In itself, this is extremely useful information. I can get a solid idea of where he is braking, what his line around the track is, etc. But what if I could compare his data against mine?

Now things get very interesting.

Turn 6
My best lap around Thunderhill, ever, is a high 2:07. That was done in late 2013 and it was done on my 2011 ZX-10R configured to run at 60% power; effectively a 600cc motorcycle. In that configuration it is producing about 120 horsepower which is nearly double the horsepower of a 450 Superbike. Dave Moss, on his 400 super bike can do a 2:00 around Thunderhill. On this triple, I recorded him running a 2:03.

This comparison is between my 2:07 and his 2:03. In this first screenshot, we can see a few interesting things. At the bottom left of the screen is a distance vs. speed comparison. It shows what speed each of us are at through the length of the track. Just from this graph alone we can learn a great deal. We see that Dave starts his braking much later than me. Towards the end of the graph I am gaining more speed (I have double the horsepower) but he still brakes later than me.

Another interesting data point is the top speed. I am hitting a higher speed on the two straight portions of the track (expected) but I am not hitting a higher speed anywhere else. With the horsepower that is available to me and the more modern brakes at my disposal (2005 era brakes vs 2011 brakes) I should be reaching higher speeds in any location on the track that even remotely resembles a straight; but I am not. Something to focus on.

In the lower right corner of the screen is a graph that took me a long time to understand. The graph goes by a few different names but one of the more common is The Traction Circle. This circle indicates by data points, how close to the edge of traction you are as you go around the track. By looking at this graph, and watching it while going around the track (combining video and data is very useful) I can see where I am close to the limit of traction, and where I am not. If I am not near the limit of my traction then I am potentially wasting time.

In between the distance graph and the traction circle is a simple numeric listing of the g force on each of our bikes. In this screenshot, I am at the bottom of turn 5, one of the most difficult parts of the track imho as it is very easy to overload the traction of your tires here and slide out. The g force indicator confirms that as I am pulling 1.07g here where Dave, entering turn 6, is pulling 1.02. The rule of thumb here is that 1 g is the comfortable limit of traction. When you are over 1g you are risking losing traction and testing the limits of the tires. There are situations where you can get to 2g but then you are really trusting the tires to their limit and a small mistake means a slide.

The bulk of the screen is taken up by a representation of the track and data points for the two laps that are being compared. The track line itself shows braking and acceleration data points. The two position indicators also have vector lines coming off of them that match the gravitational forces being applied to the bike.

All of these graphs can be "replayed" in real time so that I can see where Dave's lap pulls away from me and where I catch up with him. As you can see from this screenshot, by Turn 6 he already has a sizable gap on me. He is faster in the two sectors by nearly 4 seconds. Nearly all of the gap between his lap time is in the first five corners of the track. Looks like I need to work on the first part of the track and improve my speed with turn two probably being the biggest factor. 

Lines 

With the accuracy of these GPS lap timers, we can also look at our lines around the track. Changing your line even a little bit can have drastic effects on your lap times. I have had a recent situation where I was running my ZX-10R against a friend on his Ducati 1198 Panigale. I was running in low power mode (120 hp) and he was running in race mode (190 hp). Yet when we entered the front straight of Thunderhill, he could not catch me.

Why?

My exit out of Turn 15 was significantly better than his allowing me to get to WOT (wide open throttle) much earlier than he did and thereby "lengthen" the front straight. By the time he was able to start accelerating I had already been accelerating for 50 feet. 50 feet is a long time to be idling when your competitor is accelerating. It is the difference between winning and losing in many cases. 

Zooming into the GPS data, we can look at Turns 14 and 15.

Turn 14
There is a difference between our lines. Dave goes deeper between 14 and 15 than I do and stops braking sooner than I do. Looking at the data on the exit of 15 I can see that Dave reaches 75 mph before he exits turn 15. I leave turn 15 at 68 mph. 7 mph slower than a bike that has half my horsepower.

Turn 14 Earth
Looking at the data on Google Earth, I can see the lines in relation to the track map. Dave makes Turns 14 and 15 into more of a single corner with a pronounced V between them where I have more of a shallow arc between the corners. I can see from our acceleration markers that we are both accelerating at about the same relative point but he is able to put more power down. Another item to work on.

You can download the attached Google Earth file and see both of our lines around this track. You can see that while we are quite similar (he did teach me these lines after all), we are still quite different in some key areas. Areas that I should investigate, one at a time, and see if I can practice them and if they gain me an advantage. Practice, recording and review is key.

Goals 

With this data in hand, I have some goals for my next test day at Thunderhill. I need to gradually pick up my speed going into Turn 2 and maintain a consistent higher speed through Turn 5. My lines can be sharpened in several key areas around the track to get an overall higher speed.

There are seconds to be found and with this data, I know where to focus.