Originally Posted by
79pmooney
It's not that aluminum frames break more often, it is the failure mode. I've heard a lot more stories of diamonds braking and causing crashes with aluminum than steel. Welds failing. Front ends detaching. In all my steel failures, the bike has remained rideable after tubes severed completely (barring that one metulurgy oops). Yes, they broke quietly. No, I hadn't been checking the frames prior except my racing bike which I knew full well was on its way and was assured that I could ride it to failure, no big deal.
Setting aside the fact that, as explained in detail above by cyccommute, the true failure modes of steel and aluminum are very different from what you think they are, you hear more stories of aluminum failures (however few they are, and they are very few) than of steel failures because steel bikes, despite the impression given by steel bike lovers on BikeForums, have essentially barely registered above the level of statistical noise in the annual worldwide sales of bikes for the last 30 years.
By the way, I've noticed that, as a rule, C&V steel apologists seem to think that steel frames fail
despite being steel, whereas aluminum frames fail
because they're aluminum.
If anyone has wondered why aluminum took over the market from steel so quickly (despite the understandable initial reluctance of bike companies to invest in such a massive transposition), one clue comes from a chance conversation I had with a Trek sales rep in the early '90s. I asked what the effect of introducing their aluminum frames had had on Trek. The rep immediately said, "Warranty costs are down. We're spending much less money replacing frames under warranty because the failure rate is much lower with our aluminum frames."