PowerTap SL Reading & Calibration

[roadcyclist]

Hello all,



I just got my PT SL and road it during the weekend. I haven’t really gotten a chance to read about it but from talking with the people that I was riding with and the total E spent on the rides that I did, I suspect that it reads low.

I tried to ride a flat stretch at 25 mph and it read between 230 and 280W; does that sound accurate to you?



Does the receiver have to be calibrated?


Thanks!

 

[Alex Simmons]

Hello all,



I just got my PT SL and road it during the weekend. I haven’t really gotten a chance to read about it but from talking with the people that I was riding with and the total E spent on the rides that I did, I suspect that it reads low.

I tried to ride a flat stretch at 25 mph and it read between 230 and 280W; does that sound accurate to you?



Does the receiver have to be calibrated?


Thanks!

Calibration is unlikely to be off (but if you are really worried about it you can do the test described here to check).
http://midweekclub.ca/powerFAQ.htm

Zeroing the torque setting would be a good idea every so often as a non-zero setting will result in incorrect power readings (you will read the user manual, won't you? )

For a 25 mph ride on flat roads it might require anywhere from 100 - 600 Watts depending on conditions and your individual set up. 230-280W, assuming no wind and dead flat is quite plausible. Plug some numbers in over here to see what it says:
http://analyticcycling.com/