GPX Pro Lap Timers, and Data-Loggers, as well as Tachyon Action Cameras at CornerSpeed, 082-851-3782

I had an opportunity this weekend to collect data from another rider using the GPX-Pro. I like using data acquisition as a coaching tool and I thought folks might be interested in what even the simplest data acquisition information can tell you.

Here is a chart I created from GPS Studio. At the very top in the left hand corner, you can see two laps, one in blue - a 2:44 lap and one in red - a 2:02 lap. We'll call the 2:44 lap Blue Rider and the 2:02 lap, Red Rider.



In the first panel, we can see two lap traces. The outer lap trace is for the Blue Rider (2:44) and the inner lap trace is for the Red Rider (2:02). The red and green segments for each lap trace indicate whether the rider is accelerating (green) or slowing (red). You can see a great deal of commonality on in the braking areas with many shared reference points. A few obvious places where braking reference points are dramatically different include Turn 1 (no surprise) and the entrance to Turn 7.

The next panel down shows each rider's speed at every point on the track. It's clear that the Red rider is faster over most sections. While interesting, these first two panels don't provide nearly the quality information provided in the next two.

The next graph down (the third panel) shows longitudinal acceleration. Here we are finally at some interesting and informative data. The positive y-axis shows us not only when the riders are accelerating, but also how HARD they are accelerating. Similarly, the negative y-axis shows us how hard the riders are braking.

Before delving into details, take an overall look at the graph. On the braking side of the graph (the negative g's) note that the Blue rider seems to average about -0.20 g's of braking. The Red rider, on the other hand, averages more than twice the braking force, with several situations in which they are braking three times as hard at the same location on the track. From a coaching perspective, this tells us that Red Rider is not yet comfortable exerting any particularly strong brake force. It appears that their comfortable level of max deceleration is somewhere in the -0.30 g's range.

Looking at the individual labels green labels, we can see the following:

A. At point A we can see that the Blue rider lets off the throttle substantially before Red rider and then proceeds to "coast" into the turn. Even more specifically, they are coasting immediately after "wheelie hill", where Red rider eases up and the throttle and then gets aggressively back on it.

B. At point B, which is the exit of turn 4, we can see both riders get on the gas at the same time. Blue rider accelerates, but only to their comfort level likely well short of the bike's acceleration capability. Looking across the graph we can see this pattern repeated showing the Blue rider comfortable accelerating at a maximum of about .35 g's. The Red rider does not show these same artificial plateaus in acceleration. We can also see the Blue rider slows much earlier for the entrance into Turn 5.

C. At point C, we can see Blue Rider getting out of the gas much earlier for the entrance to Turn 7, braking about 230 feet before the Red Rider. There is a great deal of time to be made up here. We see peak deceleration at -0.37 g's and then the rider coasts into Turn 7.

D. Point D is the end of the front straight. It's not surprising to see the Blue Rider slowing much earlier given the nature of the corner. The Blue rider begins slowing 555 ft earlier and then coasts through the turn. This is another area where significant time could be gained.

The panel at the bottom of the screen shows lateral g's, or how hard each rider is willing to corner. Looking at the graph overall, it's great to see the Blue rider not seeming to favor cornering one direction over the other. In both directions, he appears to be comfortable at .50 g's of lateral acceleration. This is illustrated at points A and B.

B. Notice at point B, the Blue rider starts their turn later. This is the Turn 5 & 6 combination. In combination with the longitudinal graph, we can see the Blue rider is at maintenance throttle through turn 6 (0 acceleration g's), while the Red rider carries more speed, but then trail brakes to the apex of 6. This different in speed is also reflected in the lateral acceleration spike in the middle where the Blue rider straightens up the bike between the turn turns, and the Red rider treats the 5 & 6 sequence as one long turn.

C. Point C illustrates the the difference in the entrance to Turn 1. Red rider is turning much earlier then the Blue rider, who appears to be taking a very straight line through the turn one transition and onto the flat.

As a coach, this information helps to show that target areas for improvement aren't actually cornering speeds. Yes, the Red Rider carries, on average 10 or so miles an hour more speed through the turns. However, the big gains are to be made learning to use the brakes more effectively, i.e. being able to slow the bike more quickly followed with the rider working to be more aggressive on the throttle. On average, the Red Rider is 30 mph or more faster on the straights. This underscores the slow in / fast out rule we hear about so often.

-Curt