More iAero DFPM Compairsons

[Silkhope]

Used a new PT Pro + on my Saturday 62 mile ride and on my Sunday 38 mile ride. The saturday ride was so close between the two meters, with average power at 160 w and 160.2 w. Sundays ride showed a 10 w difference between iAero and PT Pro +. Did wind offset and tried to be sure iAero had plenty of time to adapt to air temp. It did warm up a little quicker on the Sunday morning ride. Any comments would be appreciated.

tlp_03_21_2009_0855_62_Miles.csv

Saturday ride file

(2.57 MiB) Downloaded 274 times

tlp_03_22_2009_0859_38_Miles.csv

Sunday ride file

(1.56 MiB) Downloaded 269 times

[Velocomp]

Your Saturday ride is dead-on. It's nice to see this because your ride temperature varied from 40F to 62F.

You have a slight negative ground wind on Sunday's ride. If the ground wind is set to zero, the two ride files are within 4W of each other.

Note that you're making an assumption that your PT readings have absolutely no temperature dependence. This is an unverified assumption.

[samisrour]

Did you zero out your powertap, after you took it out in the cold temperature? According to Powertap tech support, it needs to be calibrated if there is a big temperature change, when you start your ride.

[Silkhope]

I did zero out the power tap. Do it every time before I ride

Since my original post, I find that every ride shows a 5 -10 watt difference in average power. Now that warmer weather is beginning to set in, I'm sure a new session of coast downs and calibration ride will bring things even closer.