Originally Posted by
gregf83
Your example is not applicable here as we are talking about people. Put on 50 lbs of fat and your knees will splay out further from the center which significantly increases your aero profile plus all the other disadvantages of extra weight.
The only relevant component is air resistance on the flats, not the weight. So if the guy lost 50 pounds but had the same aero-profile his speed would be unchanged. And if he gained 50 lbs and had a better aerodynamic profile his speed would increase.