Among cyclists I know, many ride steel bikes and a good number have experienced frame failure of some sort. Really, I hear stories about it all the time. One woman described pedaling through town when suddenly her bicycle felt wobbly and loose. Turned out the seat tube had cracked, just above the bottom bracket. Another had a similar experience with his first bike: The downtube detached right at the bottom bracket joint and he had a bad fall. I have also heard multiple accounts of snapped chainstays.
Anecdotes like this make me think about frame failure in relation to frame material. We know that steel bends, whereas carbon fiber snaps. Steel fails gradually, whereas carbon fiber fails suddenly and catastrophically. And this is why we consider steel a safer material for frame construction. But what I am wondering is: How does this difference translate into real world experience?
What gets me about the stories of steel frame failure, is that the cyclists never see it coming. From their point of view, these too are sudden failures. In reality, I do not doubt that the failures were in fact gradual - but save for checking for evidence of stress with a loupe before every ride, how does the cyclist benefit from that gradualness?
Based on my limited experience test riding roadbikes, I am not attracted to carbon fiber frames. I prefer the ride quality of steel and titanium. But I am not sure I share the safety concerns about (quality) carbon fiber frames that some voice. Sure, in theory the frame can fail suddenly and catastrophically. But in practice, how would this differ from the gradual failure of steel that to the cyclist feels equally sudden?