Originally Posted by unterhausen

I take it you have never done any engineering work with carbon? I was mostly addressing people's examples of vintage carbon that wasn't much lighter than contemporary steel frames. Designers were being conservative because they weren't sure there were directions where they could live with lower strength. The benefit of steel is that it's isotropic and the downside is that there isn't much you can do about it. Making isotropic carbon is heavy, much heavier than necessary for bicycles. Look at cheap carbon forks on hybrids for some good examples of this. I'm sorry my post was too subtle or I was unclear. I was aware of what could be done with carbon back then. Everyone knew the trick was designing a structure that used carbon wisely. To be perfectly honest, I was at a loss at what was really safe to do on a carbon bike frame. I was sure I would have to over-build or suffer some failures or both. I'm sure I wasn't alone in this, it's a fundamental problem and you can look at examples of vintage carbon frames to see it in play. A lot of this knowledge is pretty common now, but it wasn't in the early '80s.

As far as analyzing a bike frame well enough to optimize it in any way, my deck of fortran cards was about 3" thick for a flat 6x6 sheet of carbon with various layups. Extrapolate that to a bike frame, and that would be a very large deck of fortran cards. I had to be careful how much I ran it or it would have affected my grade, computer time cost real $ back then.

The examples you give have large loads that can be optimized for carbon and have no need to be isotropic Maybe in the early '80s the military was having stuff designed like an F1 car, but not on any of the fighters I worked on. For example, the F16C/D was designed about that time and the only carbon I remember was in the horizontal tails (stabilators) that were essentially just flat plates glued to an aluminum honeycomb. There was probably more, but I never had to fix anything else that was carbon.