10 October 2011

Ride 48km and what do you get?

Proof that bicycle components are lamentably fragile, that's what.

 Brand new SRAM Rival crankset; failed at kilometer 48 of its first ride.  Given that the Apex crankset has 1380 km on it, I'm going to suppose that this particular chain ring made it out of QC and should not have.
I don't think it's spalling, as such, since it looks like some kind of ductile failure making the teeth smaller, but it's certainly not good.

And I was nearly stopped, too, with one foot down and turning to get out of going down an unhelpful bit of bike path in a park.  Not a high stress situation.


Janice in GA said...

Huh, that's wild. Did you buy it at a local bike shop? I hope you can get $$ back for that.

Graydon said...

I did buy it locally, they're great guys, and I'll be taking it in tomorrow whole and entire, possibly so the guy who does ordering can beat the SRAM rep with it. (I should remember the Kona gloves while I'm at it.)

Not the first chain ring I've bent, either, though the first one from a "good" grade of part.

Janice in GA said...

I've never even IMAGINED bending a chain ring in use. But I'm wimpy and smallish and not very powerful on the pedals.

Graydon said...

I'm quite sure it was a manufacturing failure; about a fifth of the chain ring -- which is supposed to be hardened -- had a ductile failure, which is really inconsistent with having actually been hardened. Especially since the actual load was low when it went. (I'm kinda pleased about that; having it go while trying to bounce a rail underpass and doing ~45 kph in the near-dark would have been *much* worse.)

I won't say I'm not thinking about Ti chainrings now, because this whole thing makes me anxious, or that I haven't bent chainrings (or crank arms) before, but those were much lower on the food chain and not meant to deal with someone heavy. (the Apex chainrings, one step down, worked fine through ~1400 km and are not even showing any particular wear.) So I'm pretty sure it's just that this one slipped the QC.