Saturday, August 21, 2010

Mt Tam Double Results: rank vs time

I've been a bit busy, but I got curious about the statistical spread of the times in the recent Mount Tam Double compared to other events. The Mount Tam double isn't a race, more a ride where the goal is to finish. But it has a deadline so riders at least must make an effort to hurry to some extent.

Anyway, without further delay, here's a quick plot:

rank versus time for three events

The result? The times are tighter in the Mt Tam Double than they are either for the 2008 Dolphin Running Club Embarcadero 10 km running race or for the 2009 Mount Hamilton Low-Key Hillclimb.

A simple explanation is in both the hillclimb and in the running race speed is somewhat proportional to power. On the other hand, the double century includes time descending and riding on the flats, at times with considerable wind, in which a proportionate difference in power results in a considerably lesser difference in speed. So the result's not a surprise.

Of course the cut-off time has an effect, as well. You can really see that to the right of the plot. The "long tail" of relatively slower finishers is missing from the double results. Those who would have finished slower didn't finish, or didn't bother to start.

Anyway, it's a mistake to over-analyze the data. I thought the plot was interesting.

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