What should I do for 1.75 lap sprint event?

I'm using RaceChrono for Sprint events, for example this one last weekend at Mallory Park:

You can see that the start and finish lines are in different places, and RaceChrono copes with this well.

However, next weekend I will be at Castle Combe, and their format is over a lap. We start in the pit exit, drive 1.75 laps, and finish just before the pit entry. So this means that the finish line is crossed twice, but only the second time matters.

A similar format will be used at Goodwood in a few weeks time.

Any suggestions how best to configure RaceChrono?


  • RaceChrono doesn't have Finish line that can be passed twice on a single lap. So I suggest to have the start as "Start" or "Standing start" (since v2.20) and the finnish as "Start/Finish". The complete lap will then appear as two laps. It's not optimal but it's the best I can think of...
  • edited March 2013
    Okay - I'll give that a try.

    I hear the iPhone Harry's Lap Timer users want to try putting the finish line as half of the track width, and then drive to the right on the first pass and to the left for the finish. I don't think I'd want to compromise my driving, or trust the GPS accuracy!

    Thanks for the hint regarding Standing Start, which I hadn't noticed before. I've just tried out this feature on my Mallory Park data, and it changes the recorded time from 1:19.30 to 1:22.33. Since the official time was 1:19.29, I prefer the old method - but I can't see why it is making such a difference. Any thoughts?
  • edited March 2013
    V96GLF, not sure... Can be any of the following:
    1) Standing start in wrong place (improbable, given only 3 second difference)
    2) Car is slightly moving before the actual start
    3) The GPS trajectory is slightly "moving" before the actual start

    If you look at the speed graph on the start you probably see it. The standing start detected a start 3 seconds early, so you should look at the 3 first seconds of the graphs.
  • Ah yes, there does seem to be a drift period at the start, if I view the time axis. For the first 2.9 seconds I'm building from 0.1 mph to 2.2 mph, and then it ramps up properly. I wasn't actually moving, so it must be GPS drift. Is there a way to filter this out? Perhaps that's a feature request ;-)
  • Did you do a burnout at Mallory? That could account for the false start. As for analysing 1.75 laps, you could always export the data as CSV and use Xoomcentre, written by a speed eventer and actively supported on uphillracers.com:

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