AlgarveCycling

Because, because, because this is the real World and not hypothetical physics in a perfect environment! Note what I wrote - I did not suggest that there was no difference, I wrote that there would be a small difference. This is generally true.

W/Cda is relatively small between a larger cyclist and a smaller cyclist when both are presenting a good aero position on the bike, certainly not enough to overcome the W/kg advantage. A large, overweight person who cannot adopt an efficient W/Cda will, of course, be inefficient.

This is one of the many reasons that Ganna et al dominate flat TT's vs noticeably smaller riders, few freakish exceptions aside (think Remco), from time to time. Lighter riders take over when gradient counts against the heavier riders but we're talking flat.

Obviously, there are other variables too - it isn't just about W/kg, W/Cda etc. But for the sake of this basic discussion and not going crazily in-depth, the above is generally the case.