Speed data can often be misleading because carrying more speed in one portion of the track can often cause a drop in speed in another. Entering a speed too fast can result in a slower corner or exit speed, and a compromise must always be found. From speed data alone, it is almost impossible to deduce whether or not a rider is sacrificing too much speed in one area in order to gain an advantage in another. The time saved or lost is what’s important, and here sector times can be used to guide the rider.
In this example, speed data is shown for a rider on two laps in the same session. On one lap (blue), the rider enters the turn with more speed than the other lap (red). From the speed traces, it is apparent that there is a sacrifice in exit speed on the blue lap. We can find which method is quicker by looking at segment times for that particular section. The lap report, based on the segments the track has been split into, shows that the Turn 1 exit speed on the blue lap is 107.02 mph, compared with 107.90 mph for the red lap, for an increase of almost 1 mph partway down the next straight. The entry speeds for the segment are almost identical. In order to see the time saved or lost, however, we must consider the entire section: from the beginning of the braking zone for Turn 1 to the end of the following straight. We can either create a new segment on the track to do this and add the appropriate segments, but the software generally provides an easier and quicker option.
Racepak’s DataLink software allows you to create any length of segment on a graph by marking the beginning and end of the segment with the [ and ] keys. From here, segment information – including time and speeds – can be evaluated. Here a new temporary segment has been created that spans the area of interest, and takes into account the time saved or lost under braking as well as the time saved or lost over the length of the next straight. The segment is marked by dashed lines at the beginning and end, as shown in the second graph.
The data shows that the overall time for the created segment is 8.75 seconds for the red lap versus 8.79 seconds for the blue, a difference of .04 seconds. The red lap is quicker, an almost contrary conclusion to what the speed graph alone shows. On the graph, speed is considerably quicker on the blue lap entering the corner, whereas it appears very little speed on the exit is compromised. However, it’s the time saved and lost that must be considered, and the quicker entry does not offset the lost time on the exit.