Originally Posted by
hueyhoolihan
i don't see how the headtube and fork tines represent 3% (plus the small amount added by the rest of the frame that's caught at a 10 degree angle) of the total frontal area exposed to the wind by rider and bike.
Aerodynamics is infamously complex and counter-intuitive.
Keeping in mind that I'm not an expert: It's not about size, it's often about turbulence caused by the shape of the tube. Larger tubes in the properly designed shape are typically more aerodynamic.
Aero bikes also pull out all the stops to reduce drag, such as internal cable routing; using part of the seat tube to shield the rear wheel; putting brakes behind fork and seat tube, and so forth.
the vast majority of the wind would STILL be caught by the rider's frontal area.
Rider position does have a significant impact -- 2 or 3 times greater than the frame. That doesn't change the fact that a bunch of little aero changes can make aero advantages.
And yes, it's been proven, both in wind tunnels and real-world conditions. Wind tunnels may be a bit optimistic, but they aren't off by an order of magnitude.