For a frame of reference, Cervelo is touting the P4 as the most aerodynamic frame ever devised--legal or otherwise--and their quoted savings over the P3 is 30sec over a 40K TT.
As I've come to understand it, it's 98% rider position. Once you're aero with your body, you can maybe shave a couple minutes with equipment.
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"Unless he was racing there was no way he could match my speed."