Wednesday, August 17, 2011

Bike Log Day Two

There is no bike log from day one. I wasn't going to log anything. After all, i probably won't bike to work for more than a few days this time. Don't worry. I won't post anything if i don't have anything to say.

The trip to work is 6.3 miles. My bike computer (odometer) said 10.11 km. I've not calibrated it to four significant digits. I haven't had this unit very long. I could have told this unit to read out in miles, but for no reason that i can discover, i told it to read out in km. So if i'm listening to jazz music on my mp3 player, i suppose it's Kilometers Davis.

It took 36 minutes and 25 seconds, according to the bike computer. My wrist watch said it took about 50 minutes. The bike computer keeps the time of day accurately. But if i stop for a street light, the bike computer stops too. There's no way that i was stopped for fourteen minutes. But i was stopped for perhaps five. I stopped my wristwatch stopwatch a bit later than when the bike computer would have stopped, so there's another two or three minutes. This anomaly is about six minutes. The man who has two clocks has no idea what time it is.

The average speed was 10.35 MPH. Again, this isn't calibrated to four significant digits. I'd read this as ten and a third MPH. The numbers probably have four significant digits of precision, but not accuracy. Precision has to do with repeatability. So you can think of the distance as a unit similar to miles, and compare day to day numbers with four digits. Unfortunately, though the bike computer has an Average Speed readout, and although the bike computer manual says that there's a trip timer, the only way to get trip statistics is to reset all values in the computer. So i lose the odometer setting. However, this value matches the bike computer's average speed readout, despite the fact that it also averaged a few previous trips. While what really matters is distance, what tracks progress is speed. I'll likely focus on average speed in the future.

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