Originally Posted by bbc

I may be missing something obvious but I have always wondered why bike frames don't have foam (or some similar light material) injected into them.

I would imagine it would help with a number of issues, especialy with the new thin wall frames (both Al & steel) such as the following:

dampen vibration
increased structural integrity
help absorb light impacts so frames dent or ding less

I understand Bianchi now lines the inside of their "super thin wall" racing frames w/ some sort of foam.

Has anyone seen this or can anyone explain what I'm missing as to why this would not work? It would only add 2-4 oz to the frame.

I have half a mind (but even less money) to go buy a used cannondale frame and spray in one of those self expanding foams just to see what would happen.

The down tube and lower half of the seat tube would be accesible in most frames. The head tube obviously would not work and the top tube may be inaccesible as well.

Thanks in advance for any info you might have.