Originally Posted by WhyFi

Yeah, but it's watts/drag which, given similar on-bike position, is going to scale differently than w/kg. So the bigger person making more absolute power will have increased frontal area and drag, but it'll increase at a much lower rate. Think of a 2x2x2 cube vs a 3x3x3 cube - the volume of the 3x cube is 3.375 times greater (27 vs 8), but the frontal area (one face) is only 2.25 times greater (9 vs 4).