Recently I found I had cracked my 3-year old Aluminum frame CX bike. Pretty bad. Both the down tube and seat tube, just above the bottom bracket. Shit happens, I know. Damn glad it wasn't carbon, but if it was carbon maybe it would not have failed, I know. But it got me to thinking
- With an aluminum frame, are there certain failure modes to be looking for? Should I be looking for cracks in areas X or Y more so than Z, for example? Do certain manufacturers have stress risers around the BB while others might have issues at chainstays?
- Does aluminum have a short life expectancy? Should I just plan on replacing an Al frame every couple of years?
Also I know I need to take into consideration that I ride everything with my cross bike - cross races, practice, fire roads, MTB trails (and a handful of MTB races), road miles... so I have certainly gotten some use out of it.
Of course the simple answer will be "you should have went with carbon fiber/steel/Ti" et al. I am not a metalurgist but I am guessing different metals will have different failure methods/rates and it's all dependant on frame design, tubes/butting, etc. While I am thinking that perhaps a steel or Ti may be better for my, ahem, uses, maybe I just got a bum aluminum frame and shouldn't write them off.
What say ye?
3 years seems pretty early. Depends on how thin the tubes were and the quality of the bike. I've seen them crack sooner but most manufacturers are better than that.
AL usually cracks at the welds if it's going to crack. Certain bikes are known to crack in certain areas but it's just a matter of which weld, usually.
Depends on how thin the AL is. The really thin stuff maybe you get a season or two. I have some low end Ridleys from 2007 that I am still racing.
All frames will break or have a failure mode. Just a matter of knowing what you're getting, what to expect out of it and inspecting it often.