Here's an odd question. I've got a friend who bought a damaged carbon fiber frame. He sells chemicals that are made to repair carbon correctly. I'm sure he did great at that. Here is where my question comes in. He's a newbie to biking and to add additonal strength to the frame, he filled it with a expandable foam that when it hardens it becomes very stiff but light. Is he on to something here or is it likely to make the frame too stiff. I'm assuming they are engineered to flex ata certain rate to absorb shock with enough stiffness to be quick. What do you think?