Originally Posted by Kapusta

Making a categorical statement carries with it a high burden of proof.

The OP has stated categorically that stiffness does not matter. Period. And this assertion is based solely on the idea that there is no difference in efficiency. What I am challenging is this idea that same efficiency = no difference.

I did not say that since pedaling a flexible frame feels different that it is in fact less efficient. (Defined strictly
by power into the pedals vs power out in the wheels). What I said was that it is in some way different.

Just because two systems ultimately have the same efficiency (power in vs power out) does not mean that we as biological creatures are always able to deal equally well with them.

Take the example of gearing. Strictly speaking there is essentially no difference in the efficiency of a higher vs lower gear. Does that mean it does not matter what gear you are in?

Introducing a spring into a system absolutely changes the way we interact with it. And that is immediately evident in how it feels. In fact, how something feels is often one of the best indicators that there is a spring somewhere in the system, be it in pedaling, braking, or pulling on the handlebars.

I think your tire pressure analogy is off base, here. Are you suggesting that tire pressure categorically makes no difference? Tire pressure is probably a perfect example of when one should NOT be making categorical statements.

Where I think you and I may be in agreement is that one should not assume that they know exactly what their subjective experience is caused by or indicates. People should not assume that the harsher ride of an over inflated tire is faster. And people should also not assume that the flex they are experiencing in a bike means that the bike itself is less efficient.