I've downloaded and unpacked the data. Now what do I do with it?

We highly recommend that you buy and read both Joe Friel's The Cyclist's Training Bible and Allen and Coggan's Training and Racing with a Power Meter. The former is the definitive book about all aspects of cycling training (although we think he's off his rocker in the chapter about diet), and the latter is the definitive book about power-based training.

Also, if you buy either of these books through the links below, we'll get a referral fee in return, helping us to support this web site. Thanks!

Does the output of ptunpk exactly match that of the software included with the PowerTap?

Almost. If you run it in compatibility mode, using the -c option, it matches the PowerTap software's output exactly on everything but the time values, at least for the five sample rides we've tried it with. The times are a little off, but not by more than 0.1%, so we don't consider it a big deal.

That said, the PowerTap software does some weird things, like converting from kilometers to miles by multiplying by 0.62, but then reporting the miles values with five digits after the decimal place. If you run ptunpk without the -c option, it will unpack the data in the way we think it should. The results mostly match up with the official ones, and are almost certainly identical within the range of accuracy of the device.