I voted none since this is road cycling, and the only frame I ever had fail was a steel wal-mart mountain bike frame I snapped doing things I shouldn't have been when I was 15...snapped it in half during a jump that went wrong. Needless to say I had a rather impressive set of injuries.

Anything can be broken by a 15 year old with too much testosterone and too much time on his hands


edit: oh and for the record, I'm pretty much aluminum only. Both my bikes (road and mountain) are 7005al, and both are darn good rides.