Originally Posted by
MKahrl
Bicycle Quarterly has been doing double blind tests with identically built bikes with identical components, tires, tire pressure etc and a group of testers that ride the same size bikes. The differences are in the tube diameters and tube wall thicknesses. It's expensive and labor intensive testing. Preliminary indications are that for some riders a more flexible frame is faster. Why that is is a matter of conjecture.
One of the european mags did a test of a new carbon Pinarello (I think) vs. a vintage steel one, using same wheels. Had several pros ride the both, and timed ascent, measured power, etc. The new bikes were marginally faster, but the pros really disliked the flexibility of the steel frame. I'll try to find the article.