Originally Posted by
GuessWhoCycling
2010 Trek 2.3 broke at the bb, from under around to the upper section of the down tube. Almost as if it were cut with a pipe cutter.
2007 Lemond Chambery. Snapped at the rear section of the chainstay just before the dropouts. Spine design carbon top tubes and alum lower chasis configuration.
Edit, what am I thinking! Lemond was a 2007 not a 2014. My current roadie is a 2014.
Interesting - the two that broke were close kin.
And I'll bet they were both driveside chainstays. All of the bikes that I've ever seen "wear out" - ridden into fatigue failure - were cracked in the right chainstay.
I would guess the beefiest aluminum stays are more proof against this.
Originally Posted by
cyccommute
Crashing a bike seldom breaks frames. If you crash into something, the chances of any frame material surviving it is minimal. But just falling over or even crashing on a mountain bike doesn't break frames. In my experience, frames break through usage, i.e. metal fatigue. I've broken 3 of them that way and I've broken one because I made a wrong choice on a seatpost.
Your first sentence and second don't seem to match.
The idea we are discussing is that "crashing the bike" means that bike received a major wack, not just the rider. And in those cases where there is an impact against the frame, thinner tubes seem more likely have an impact that makes the frame structurally unsound. Thicker tubes can shrug off impacts that will dent or tear a thin tube. The "beer can" problem.
There are also places where dimensional limits prevent the material from being used to its full strength - like steerer tubes and dropouts. Aluminum dropouts aren't thick enough to not have replaceable derailleur hangers, but steel and ti are.