Gut Perception of Speed#

Tue, 04 Apr 2006 13:00:00 +0000

Today I was able to download the GPS track of the Berlin race and have a look at it.

The first and most obvious point is that the GPS will sometimes record badly off-track points which stuff up my max speed and make the route look more interesting than it really is: there are usually only about two or three of these per hour and they're easy enough to delete once in the computer. The picture you see here is after deleting the really badly wrong points, so although I say it's obvious, the reader may be excused for considering it less so. There are still a few that look a bit funny but I left them in because they're not so high above plausible speeds that they break the scaling on the axes.

The second is that it seems to think I fell much later than i thought I fell: the downward spike to zero is at around the 19k mark, where I thought it was more like 15k. Which leads me to suspect that even if I hadn't fallen the end of the race might still have come as a total surprise ...

And then the other noteworthy item is just how much difference there was between the actual trend in speed and my perception of it (based on looking at the GPS on my wrist from time to time); I thought we were picking up the pace a bit in the second half, but it doesn't look that much as though we were. Also my solo pace in the last 2k is basically the same as the pace the rest of the way through: if that really is the fastest I can go, then in the hypothetical situation where I hadn't fallen it might even have made not much difference whether I'd noticed the finish or not - there still wouldn't have been much I could do about it. :-(

I have to admit that my knee would be a lot more comfortable in said hypothetical, though. Road rash makes moving it sufficiently uncomfortable that I really don't want to do it for fun, so I think I may be skipping Tatem tonight.