One trait of frame flex proven by mechanical tests is that larger frame sizes flex far more than smaller sizes. This is true for steel, aluminum, titanium and CF.

Ironically, larger & heavier riders need to use larger frames and smaller lighter riders need to select smaller frames.

Larger riders usually find the more flexible large frames will provide a compliant ride but larger riders might also discover some unwanted flex. Smaller riders often enjoy the performance benefits of a stiff and responsive frame, but might find the reduced compliance of smaller frames to be uncomfortable.

I have a light-weight friend who has a collection of smaller sized titanium bikes that were produced about 10 years ago. He enjoys the very compliant ride of these bikes. He also finds modern race-level CF and aluminum to be way too stiff for recreational use.

I'm a larger guy who has large frames in CF and steel. I find the CF bikes to have the right amount of flex. I have had titanium bikes that were overly flexy with bad handling characteristics. I find some steel bikes to be good riding bikes but not stiff enough for very fast rides.


The point to remember is that don't use another opinion of what might be "too stiff" or "too flexy". A large guy rarely finds a bike to be too stiff and a smaller person might dislike the ride quality of a very stiff model since a small frame size might increase frame stiffness to an unacceptable level.