High CDA & input on testing protocols

[emile]

Hello everyone, pretty excited to have received my A.P.

I tried testing some helmets on a 2.8mile (out & back) course which is pretty sheltered from any wind and has premium road surface, I do however have to use my brakes to make a turn around. My "laps" are about 8min in length and I easily hold 20-22mph. The data from the different helmets was really wonky, nothing made sense and I could see the live CDA vary widely depending on which way I was heading.
I have really high expectations with the A.P. and I want to take testing seriously, would I be better with:
-longer sampling laps
-a loop type lap course which allows me to not use my brakes
-sampling at race speed 25+mph

Secondly, I used the A.P. at a local TT race, I'm getting that my CDA is 0.262 which is way off. From comparing with teammates who have been in the windtunnel, I suspect to be at/or under 0.200. What settings or tweaks should I be doing to the A.P. & the race file?
DFPM was a Quarq Riken, 320w ftp, 139lbs, A.P. is mounted on the extensions but as close to the basebar as possible to avoid as much flex as possible. Speed sensor is taped to my trispoke but seems to read accurately.

Thank you!

[Velocomp]

The ride file you provided looks excellent!

One of the critical assumptions used when measuring CdA is the value of rolling resistance (Crr). Your ride file uses a Crr of 0.003--this is a very low value, which is possible if you're riding in a velodrome with highly inflated tires, on a wooden track.

A lower value of Crr will cause the value of CdA to increase.

Your ride is outdoors. Here, we typically use a value of 0.0054 (this value appears to be common also with other methods).

I adjusted your ride file to have a value of 0.0054. With that Crr value, your CdA on the uphill is 0.188 (DFPM and AP watts are within 1 watt of each other)

Ride file is attached.

Please download and use the Velo Tracker app (iOS), or email us for the Android version. This will make lap testing easier to understand.

For testing, longer is better than shorter. Avoid brakes if possible.

[BillOsler]

Please download and use the Velo Tracker app (iOS)

Are you referring to the Velocomp Velotrack app? I didn't find a "Velo Tracker" in the app store.
Is there an advantage to using the Velotrack app as opposed to merging GPS data from my Garmin aside from the fact that it happens automatically ... if I remember to start the app?

[Velocomp]

Sorry, it's "Velocomp Tracker"

If you're merging .tcx or .gpx files from your Garmin that is fine.