Hi David, at some point it would be nice if we could estimate a CdA for the whole ride or at least laps/intervals. We know the caveats of this, on the other hand the rules for estimating CdA are always the same:
- Multiple laps without braking or out and back
- Minimum of wind or disturbances (cars…)
- Estimate of rolling resistance, driver&equipment weight, Air Density, wind speed and wind direction
- Accurate Speed Signal (from wheel Sensor, GPS too noisy)
- Accurate GPS Elevation Signal
- Not perfectly flat route
There is the Cheung Method which compares GPS Elevation with a modelled Elevation from a simple bicycle model (basically Force or Power formula) solved for the gradient. Then you adjust your estimated CdA value until you have the best correlation for your two elevation curves.
I know this could be quite time consuming to develop and possibly needs a lot of server power for the calculation (minimum error search to find best-fit CdA). This is not a common utility tool, but I like to play around with it, even when I am only riding a road bike.
It could be also done without a minimum search, but maybe only for finding an average pseudo CdA for the whole ride…
I never developed such a tool, but could help with some links.