Originally Posted by
vespasianus
Oh for sure. Aero-Tri bikes have proven that. Their shapes are all over the place and bikes like the cervelo proved that a while ago. Modern triathlon bikes are the stiffest and most aero efficient bikes made. You don't need "seat" stays to make a stiff, fast bike.
I thought the question is how much seat stays contribute in a traditionally shaped but modern carbon bike frame to the frame stiffness. The cervelo guy and people like Rob English and others have said it is not much.
This is wrong.
A space frame will always be lighter than a single member of the same strength. The bikes you are thinking of, the ones with unusual frames that are without seat stays, they are prioritizing aero. Since they don't have the benefit of efficient and lightweight triangulation, their frame shape has to be absurdly, massively thick to over compensate. They are still light because they are carbon but if these frames went with a regular triangle structure, they would be even lighter to get to the same strength.