Frame Flex on GCN

[Mark McM]

Originally Posted by cachagua

I guess so, thanks. What I hoped to throw some light on is that there is a component of frame flex that puts the rear axle closer to the BB (since there had been some divergence of opinion on that).

Yes, there is a component of frame flex that puts the rear axle closer to the BB. But of all the flex components, this is one of the smallest. Since strain energy is inversely proportional to stiffness, this flex component will be a very small part of the total strain energy in the frame. While the GCN video may not be an entirely realistic simulation of pedalling, it clearly shows that the majority of the strain energy in the frame is from the horizontal twisting of the BB, not from the (linear) compression of the rear triangle. Anyone who wants to claim otherwise, will need to come up with direct evidence to support their argument.