My first post on this topic caused some confusion, sorry about that. So here is another take on the same data, forget the fact that it came from Zwift the question is purely about the relationship between weight and CdA given an experienced rider using cutting edge equipment.
I think this is a topic of interest to anyone planning to do a time trial so the discussion could be useful just for that purpose as I always thought that weight was not a significant consideration on flat courses.
The tables below show the results of some TT tests done on Zwift.
All runs were identical except for 4 variables
Sector. 2 different sectors were used, one a 1.1% uphill. the other a -1.4% downhill constant gradient
Rider weight: this varied from 45kg to 90kg in 5kg increments
Power: a rough target of 320W was set but this varied slightly from run to run
Entry speed: the laps were flying so the entry speed may have differed slightly between runs which would affect average speed. This had an effect but not a significant one.
Bike was Cervelo P5x, wheels were Zipp 858/Super 9. The rider was 1.70m and rode in an indentical good TT position every time and there was no wind. 2 runs were done of each sector.
Gribble was used to calculate the CdA for each run based on speed/power. Defaults air density and drivetrain loss were used. Crr was 0.004
TT is not my main discipline so I don’t have much practical experience with actual CdA figures. The CdA numbers look quite high given the quality of the kit and the ideal conditions. The scaling with rider weight also looks strange. The chart at the end shows that the relationship between CdA and weight looks to be linear which seems odd for a cutting edge bike and a rider in good position. I would have expected the line to curve as larger riders will not necessarily have proportionately larger frontal areas.
However hopefully there will be some with good working knowledge of actual CdA data gere so my question to them is do these figures look right?
More generally, completely forgetting Zwift, what, with best current gear and an experienced rider would you expect the relationship between rider weight and CdA to be if all other factors were equal?