I’m pretty sure I know the answer to this question but I’m going to ask anyway because I’m in a bind. Got a rental sub-9 disc w/PT from somebody and I immediately noticed a power reporting problem. Once zeroed, torque and power looked to be reporting consistent but low (40 - 50w). I checked the calibration number and it says 646. There’s the problem. My race is next Sunday. There’s my 2nd problem.
Sure, I might get lucky to get this out to them by Tues/Wed and back in time for my race but I’d rather not take that risk and see if I can manually calibrate it myself. Doesn’t hurt to ask…
Where’d you find the calibration number? What should it be?
Fred
You have to get into Test Mode from the menu. The zero calibration number should be 512 ± something like 10. So, roughly between 502 and 522. The end of the manual does a good job explaining how to go into test mode in case you don’t know.
That will let you know if it’s truly off to begin with. Generally Powertaps are right or they’re really, really wrong (like by 150 watts).
-jens
Believe me, I know it’s off. From my experience, the best way to do it is to go into test mode and just check the calibration. The middle line is the zero calibration # and should be set somewhere very close to 512. If it isn’t then it’s calibrated incorrectly. 2nd way is to see if there’s a lot of drift (top line) which means the torque tube needs to be replaced.
I had another wireless PT with a torque tube problem about 2 months ago so I’ve played with this extensively and know it well now.
There’s the problem. My race is next Sunday. There’s my 2nd problem.