To ballpark a CdA…
I know my average power: Go to a course where the average power is known. Enter into your forecast the average power for your ride. Adjust the CdA to reflect the average speed you attained for this power. A lower CdA will increase your average speed and a higher with decrease average speed. Tip: If you have Premium access enter into the Date Picker the time you attained the average speed at wattage on the course.
TT Bike in Skinsuit Aerohelmet: 0.19 – 0.22
Road bike drops: 0.28-0.32
Road bike hoods 0.32-0.36