I was asking for confirmation regarding CdA testing without a Garmin device. I would do the testing as out-and-back and start the AP at the beginning of my ride, then warm up and then do laps. After that I would use the VA to create laps and analyze. For my use case, I can select the out and back legs with great accuracy, based on GPS and on the length of the leg.
John wrote in his email that "IF YOU DON’T HAVE ACCESS TO A GARMIN THEN YOU COULD DO TESTING IN PROFILE 3, AND MARK LAPS AFTERWARDS IN VA."
Now I am a bit confused and would like to ask you the describe the differences between the two profiles.
First of all, I am an engineer, so please don't hesitate to use deeper technical explanations.
So far I thought the only differences between Profile 3 and 4 are the following:
- In Profile 4 the Garmin IQ app shows cumulative average CdA. (But I guess the raw CdA is also saved in the AP)
- In Profile 4 the accuracy is a bit higher, 0.001 vs 0.003 (I guess the lower accuracy is in order to have longer battery life or smaller data files)
Or is there any additional calculation that the AP does in Profile 4? Perhaps after the first warm-up lap that must be a closed-route lap? Here I assume the closed-loop requirement of Profile 4 is just to ensure a precise starting CdA that can be used for comparison during the ride, but other than that it does not affect the measurements after.