Powertap Pro test

vitiris said:

My Powertap Pro misreads Watts (by about a factor of 2x) but is fine on everything else. I have zeroed the Torque with no joy. I also ran the test and got the following reading for the Torque information of 497 on the bottom line and 497 on the middle line with 0 at the top. When I rotate the cranks the bottom line minus the middle equals the top as it is meant to do. Totally flummoxed 😕, any ideas gratefully received

Thanks

Sean

Hi Sean, I replied to you over at Wattage already, but it sounds exactly like my problem last year with a new Pro. I had to send it back for a new torque tube. Do a stomp test and if it's off, it'll probably need to go back. Jimmy

jws said:

Hi Sean, I replied to you over at Wattage already, but it sounds exactly like my problem last year with a new Pro. I had to send it back for a new torque tube. Do a stomp test and if it's off, it'll probably need to go back. Jimmy

Jimmy, thanks a lot. I have heard about a stomp test but how do you actually do it? An url to a webpage explaining would be great 🙂

Cheers

Sean

vitiris said:

Jimmy, thanks a lot. I have heard about a stomp test but how do you actually do it? An url to a webpage explaining would be great 🙂

Cheers

Sean

Sean,

Check out this link(Q #23):

http://www.midweekclub.ca/powerFAQ.htm#Q23

Jimmy

jws said:

Sean,

Check out this link(Q #23):

http://www.midweekclub.ca/powerFAQ.htm#Q23

Jimmy

Once again thanks Jimmy 🙂 . I carried out the stomp test, hopefully correctly, I tried two different cogs and got figures of -67.5% and -71.2%. Does this sound correct and what does it mean except I guess it is meant to be zero 🙁

Sean

vitiris said:

Once again thanks Jimmy 🙂 . I carried out the stomp test, hopefully correctly, I tried two different cogs and got figures of -67.5% and -71.2%. Does this sound correct and what does it mean except I guess it is meant to be zero 🙁

Sean

Oh yes, Sean....if the error's that high, you've got a bad torque tube. Call Graber and let them know.

The error should be close to zero, probably no more than a couple percent.

The good news is that I think they have parts for the Pro, as opposed to the SL.

Ciao, Jimmy

jws said:

Oh yes, Sean....if the error's that high, you've got a bad torque tube. Call Graber and let them know.

The error should be close to zero, probably no more than a couple percent.

The good news is that I think they have parts for the Pro, as opposed to the SL.

Ciao, Jimmy

Just plan for significant down time. I just had my torque tube replaced and Graber had my wheel for a month.

jws said:

Oh yes, Sean....if the error's that high, you've got a bad torque tube. Call Graber and let them know.

The error should be close to zero, probably no more than a couple percent.

The good news is that I think they have parts for the Pro, as opposed to the SL.

Ciao, Jimmy

Jimmy, it's back and I've had the wheel rebuilt and I have now tested it. Wow, it works, it reads power and I haven't been so happy in ages (yes I live a seriously sad life). I shall give it it's first outing on the club TT tomorrow night and can hardly wait 🙂 It has already made me feel better because I now have a more realistic reading on the turbo (Taxc Excel), I always thought it under read but couldn't know by how much but after a quick spin I'm guessing 300W Powertap is about 250W Taxc.

Thanks for all your help

Sean