Adjusting ride power, (torque not zeroed)

[velomanct]

the one time i forgot to check to make sure torque was zeroed, it actually needed to be zeroed, for my race.
i was a little surprised to see i average 400watts for 20 minutes, looking at the downloaded ride data.

if my torque was 20 when coasting, is there any way i can adjust the power readings to be correct.
after looking at the download, my power seemed to hold steady at the 70-80watt range when coasting.(for some reason i never noticed this in the race.)
does that mean i should subract 70 or 80 watts from all the ride data?
260watts for 80minutes seems more realistic than 330watts.

 

[ric_stern/RST]

Originally posted by velomanct
the one time i forgot to check to make sure torque was zeroed, it actually needed to be zeroed, for my race.
i was a little surprised to see i average 400watts for 20 minutes, looking at the downloaded ride data.

if my torque was 20 when coasting, is there any way i can adjust the power readings to be correct.
after looking at the download, my power seemed to hold steady at the 70-80watt range when coasting.(for some reason i never noticed this in the race.)
does that mean i should subract 70 or 80 watts from all the ride data?
260watts for 80minutes seems more realistic than 330watts.

Never had this problem personally (i check the torque at the beginning of every ride), however, this was posted to the wattage list
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Look at a section where you know you were coasting, e.g. just after
you finished the time trial. Pick a representative value for the
torque zero.

Now correct torque for torque at zero power:

Torque(actual) = Torque(measured) - Torque(zero)

Then recompute power according to the following formula:

Power(Watts) = 1746*Torque(N-m)*Speed(km/hr)/WheelCircumference(mm)

WheelCircumference is the same thing as in setup,
about 2100 for 700C

In fact, any ride where the minimum torque is non-zero is
very likely to be in need of correction.
___

and this
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http://users.icubed.com/~mayhew/mayhew.xls

paste in your data to the correct columns. set column B so that it
subtracts whatever your torque was off by, as determined above.
you can then paste the data from column C and G into the old .cvs file.
a big thanks to andrew coggan for creating this, as there's no way i could have
done the math.
_________

hope it works out
ric

 

[velomanct]

great, thanks