Low weight is fine, but unfortunately there are no standards for how well these light components have to work. At least in most automobile racing, there are standards to protect the drive and the pit crews (and the spectators).

There were some riders injured in the last two Tour de France because of broken stems. In Armstrong's famous 2003 crash, his frame had a big crack (chain stay?) and he almost didn't make it. The accident wasn't all that hard on the bike IMO, but you can't be sure.

Theough Armstrong has back-up bikes, sometimes they can't get one too him in time and the rest of us don't have the back-up bike luxury.

Al