Sorry...I don't mean to derail things...but my understanding of aluminum and carbon fiber and fatigue is a bit different. It doesn't matter how much thicker the tubing is, EVENTUALLY aluminum and CF will both fatigue into uselessness. We learned about fatigue factors with aluminum from airplanes...after so many flights, they'd always tear apart. Making it thicker, stronger, etc (which adds weight to the point where it has no advantage over steel) just means it fatigues later...it still eventually fatigues. Maybe that time period with aluminum and CF is now so long as to be irrelevant, but crashes, every impact...etc...are all just a little less life it has left. Also...when steel fails, you usually see it bending before it goes. Aluminum is more likely to just fail without warning.
Steel either breaks with a stress or it doesn't. There's no combined wear issue. To me that means light weight CF isn't really a long term tubing material. For folks who change bikes every three seasons, it probably doesn't matter...but I tend to want mine to last.
I'm NOT an engineer and could definitely have this totally wrong.
Last edited by KonAaron Snake; 03-17-10 at 10:12 PM.