Upon inspection after the break (of the crank), it was apparent that there was a micro crack that probably could have been spotted if one checked it over every day with a magnifying glass. Seriously, who is going to do that, especially for a part like bars that are under tape. It's not common, sure, but my point is that there were no obvious warning signs and it was a catastrophic failure. Carbon may be more prone to it, and the warning signs more hidden, but aluminum is not immune.