Thanks. Yes, I was hoping to have some sort of option not to export the calculated calories in the TCX file, and just let my analysis platform do the conversion using their native methodology. That seemed the easiest, but as an alternative along the lines of the drag coefficient for speed/distance estimates, you could include an efficiency coefficient option in the rider settings that defaults to 23.9% but allows us to alter it as with drag. Then the formula for the calories in the TCX file would be:
kC = (kJ/4.184)/Efficiency