Stopwatches
If you've been tasked with keeping an accurate check on performance out on the track, then a stopwatch is possibly the most important piece of kit you own. As part of the data analysis, lap times and sector splits can be used to identify strengths and weaknesses out on the circuit that may be down to the racer or the car or bike.
A stopwatch with lap counter can help to track progress over the course of a practice session or race, enabling you to see where the tyres may have started to show signs of wear or when you really hit your straps and nailed the perfect lap times again and again.