How to calculate Cda?

As most of us don’t have access to a wind tunnel, how do we go about figuring out just how aerodynamic we are (concerned more with new position on the bike than new aero equipment)?

Are speed and power our best guesses/estimates?

There are a bunch of companies coming out with products like this.

Which should allow you to account for environmental conditions and calculate a pretty accurate CDA.

BestBikeSplit can create an estimate based on a course with power and speed data.

There’s also the Chung protocol:

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BestBikeSplit can actually do it quite well, but I think you only get access to their Aero Analyzer with a paid account.

Download golden cheetah (free software) and can use aerolab using Chung method