powertap issues, questions

[AngryScientist]

last winter i bought a used powertap wheel from someone on this forum. worked great all winter. i have it on my trainer bike and used it for some workouts.

fast forward to this winter, did a trainer ride last night for the first time in about a year with the powertap wheel on. seems like the power numbers are reading super high. 500W just lightly pedaling, instantaneous power. the numbers seem to track perfectly well when i pedal harder or lighter, just that the scale seems artificially high.

is there a way to calibrate these things? dont know what model i have, but it's a wireless ptap wheel and i'm using my garmin 800 to read power. any ideas?

[yoshirider]

Here are calibration instructions

http://www.cyclepowermeters.com/powertap-garmin-calibration-check-76-c.asp

[AngryScientist]

Here are calibration instructions

http://www.cyclepowermeters.com/powertap-garmin-calibration-check-76-c.asp

nice, thanks yoshi. going to the basement now...

[shovelhd]

What is your offset number?

Change the batteries. Make sure you use silver oxide. Zinc oxide batteries will not last.

[MattTuck]

seems like the power numbers are reading super high. 500W just lightly pedaling, instantaneous power.

Did you find a new primary care physician? Perhaps someone with a spanish or italian sounding name? :banana:

[happycampyer]

No chain, no chain.

[fio]

Here are calibration instructions

http://www.cyclepowermeters.com/powertap-garmin-calibration-check-76-c.asp

This doesn't calibrate the hub. This is just a poor test for the calibration. Technically this isn't quite accurate because the effective crank arm length is affected by the angle of the arm itself, and if you're off level even by just a little bit the "length" will be wrong, which will throw everything off.

Your Garmin should be able to give you your calibration, depending on its firmware (just make sure that its up to date). It should be between 500 and 524. If it's outside that range (which it looks like it is), it'll need to come back to the factory for calibration.

If you'd like more help or have any questions, please don't hesitate to shoot me an email or a PM.

[happycampyer]

Wow, how is that for customer service!

[Tokeat]

Powertap does have outstanding customer service. On the issue at hand, try updating the software on the Garmin. I had similar issues and that took care of it for me.

[slidey]

Doper :p

[AngryScientist]

thanks for all that help, i'll try some experimenting tonight.