If we consider a frame to be loaded at the points as shown, let’s look at what happens to the various tubes.
This is what people who think rear triangle compliance has an effect on frames happens. I think this is bollocks.
This is what happens. The front fork tries to rip the front of the bike off, and splays the top tube and downtube under simple bending, resulting in the wheels spreading apart under load. This is what happens.
The rear stays do splay a little if left unsupported. But they bow outwards. There is FEA done to show this. They don’t bend the other way.
S bend stays make people think they are springy as they look a bit like a spring, but a spring is actually a coiled up torsion bar. It’s not curved like that for compliance as such.
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