Has anybody ever tried to replace any of the tubes on an aluminum bike with carbon fiber tubing? I'm talking about say an old Cannondale with a damaged downtube, would it be possible to replace the down tube and maybe others with carbon tubes? Years ago I really wanted a Trek carbon fiber bike. A friend of mine had one, I think it was a 2300 might have been 2400 or 2500 I think it had Shimano 600 components. I wanted one but didn't have the money. I inquired about just buying a frame but the cost was almost as much as the entire bike. Anyway, I like the idea of mixed materials and I always loved the looks of the aluminum and carbon frames. Specialized made one too and I'm sure several other companies did too. So I would like to make one out of an old CannonDale or I could buy a different frame but I wouldn't want to spend too much on my first try. So if anybody knows anything about doing this please let me know. I've searched different sites and I have never seen one online. I have no experience with carbon but I have worked a little with fiberglass.