This is where the whole idea is spoiled at the point of origin, though. H. says, "On a bike with optimized frame flex characteristics, the rider can put out more power with less fatigue." But nothing has been optimized. He bought one bike frame that was more flexy than the one next to it. It was supposed to be a double blind study, but two of the riders could tell "with 100% accuracy" which bike was which. In the other post he reports one of the riders in one of the five repeats of one of the tests made 12% more power on the flexy bike. This is the one result he repeats over and over.

And he does tend to cherry-pick the results he likes. On the separate topic of suspension, he published roll-down tests done on rumble strips. One was a heavy duty fork from a hybrid. One was a handmade fork from impossibly sourced tinfoil-thick blades. One of the forks was a really terrible old 1990's Rockshox, their first attempt at a road fork. At the time of his test it was like twenty years old. And it did equally well to the very skinniest bouncy fork blades he preferred. He never wrote another word about it. When he talks about his magic tires there's never any serious talk about damping.

You absolutely can feel frame flex. It makes a "good" tandem like a Burley or Trek feel like crap for an American-sized team, which is why Cannondale tandems were so great. The two bikes I've ever had head shake were a Super Sport and a Paramount, both commuting with a good load in a rear-rack-top bag. But the Paramount does feel better than the Super Sport did. It does! It has to be the definitely-flexier 531 vs straight chromoly. What else could it be? On the other hand a super stiff 90s aluminum bike might not feel comfortable but you sure can feel the raw power transfer. Raw is a good word for it. But is it really that stiff? It's made of not very much aluminum at all, and somehow it feels better than putting a skinny tire in a contemporary aluminum mountain bike, which is surely much stiffer. So - is preference for a feeling providing emotional motivation? Is it Heine's preference in this instance? If so, is that what we should really be chasing?