Originally Posted by
Bacciagalupe
Stiffness does appear to improve control in certain situations, notably on the descents, and probably during sprints. Otherwise, I'm not really aware of any reason why frame stiffness would genuinely improve power transfer.
And that's very important. You only approach your potential if you don't feel like you're taking excessive risks at it. Riding a bike, like many things, has a big mental component.