Lifespan of Parts
 

After having my crankarm snap in half this morning on my 'cross bike, I started wondering about the lifespan of certain critical parts such as stem, handlebars, cranks, etc.. These cranks were about 11 years old and saw some pretty heavy use, but I didn't think about them ever breaking. I have had what if thoughts run through my head of my bars or stem snapping though. Do any of you think that after x-many miles a part might need to be replaced due to fatigue even though it is not showing any signs of immanent failure?

11 yrs is pretty good use out of a crank. I think you got your money's worth. Hope you didn't get hurt.

That musta sucked a lot.....good thing you didn't impale your shin or something.

Actually I tore a chuck of flesh out of my calf from what was left of the crank still on the bike, then it started to rain for the walk home. Catastrophic Failure would be the saying of the day for me.

Ah, ouch. Sorry to hear that.
I've definitely heard stories of old stems suddenly snapping during riding.. so I don't know, I guess if I were you I might want to be safe and get a new one or something. They're not too expensive, and you'll be able to get a little peace of mind.

It would be quite easy to make parts basically indestructable for maybe a pound or two more of very carefully placed material per group. Once you start buying high end stuff though it's so close to the limit of current design and manufacturing that it's bound to eventually break.

Aluminum is especially prone to this due to its finite fatigue life.

sorry to hear about your mishap. typically parts don't fail until after they reach their cycle life or the point of plasicity. alum has a fatigue cycle life, but parts should be designed for use for many years. I always worry a little when I go down a steep hill or go around a tight curve.

I wouldn't go buying new parts just because they are old as long as its performing well go with it. Like my daddy says "ride it till the wheels fall off"

Good thing you were not injured badly, now snapping a crank? That's a Badge of Honor. Frame that puppy :D

I don't think it would be a bad idea to replace the stem and bars. You've obviously ridden them hard and the peace of mind might be worth the relatively small cost.

It's possible that a crack in one of those parts could grow from "too small to detect with the naked eye" to "catastrophic" over the length of a ride or race, so just inspecting your bars and stem before riding might not be enough to keep you safe.

I have been told that wear parts like chainrings, casettes etc. are good for 5000 miles. I know lots of riders have gotten much more out of these parts. Any comments on mileage of these parts? Broken crank arm would be from material fatigue not just wear. If your really concerned about parts failure a product called Magnaflux, used to find defects in welds & magnets, etc. can be used. It is a dye that reveals small defects. Do not know if it is safe to use on carbon parts.

Chainrings, cassettes, chain etc. are far easier to check though as visual inspection certifies their condition. Cranks and especially handlebars are far more dangerous.

Having a stem or handlebar snap in half during a 45 mph hour descent would probably not be too much fun.

Yup. See Hincapie in the Paris-Roubaix this year.