In this video, Mark Cote explains the wind-tunnel testing and software. Colorado Premier Training will set Aaron's (our test subject) bike up first and get some baseline drag data without the rider-only the bike.
Once the baseline data for the bike is determined, that can be subtracted out for the tests when Aaron is on the bike trying out different aerobar width positions - this allows the rider to know exactly the drag (or time savings) each new position entails.
Aaron will go first through a baseline test, then 3 different aerobar width positions to determine which aerobar width (baseline, narrow or wide) yields the least drag.
Aaron got some surprising, non-intuitive results which goes back to the theme of what position works good for one person, may not be good for another.