Dérailleur Fail

Huh How’d that Happen? Dérailleur broke apart at the elbow. No crashes or big hits. Just failed. I’ve never seen anything like it. This is Pam’s Travel bike, so it could’ve been damaged in transit, but nothing noticeable.

The only other epic fail I’ve seen is a chain ring.

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8 Comments

Failures like this are why I quit using Shimano in the early ‘80’s. I use them now, but only if I have to. I expect by the logo on the wheel this is a Shimano derailleur, yes?

I’m going to go with structural damage from travel. I put my bikes in cases all the time, and there is tremendous pressure on the derailleur most times. It’s also in a corner of the suitcase which is where baggage handlers tend to drop them.

That bike travels folded in an S&S case with the derailleur removed. I’ve also seen a really old campy derailleur spring fail.

Naw, that’s just a fluke—the derailleur is probably 3 years old or so. There’s no pattern here and I’ve traveled thousands of miles with Shimano. Any manufacturers has rare failuers like this. It’s just weird that it failed there on the elbow.

I had this happen twice! Both times a stick or some kind of debris got into the chain and pushed the dérailleur into the spokes while I was in high torque mode. This pulled the dérailleur around until it couldn’t rotate anymore and snapped at the weakest point.

I’d contact Shimano regarding failure. There may be a problem in the casting. I have had other failures (the last due to an attacking stick), but the failure of a casting on a front derailleur due to a metal void is the closest I’ve had to this.

I’ve seen this many times - it’s the classic “JRA” failure.  The way that the cable is wrapped around the frame indicates that the rear wheel was involved; let me guess, it happened either just after shifting into the large cog, or when standing up and putting sudden extreme force to the rear wheel.  The first thing I would look for on the rear derailleur is some sort of mark on the cage or on the pulleys that was made by a spoke.  The usual scenario is that the derailleur hanger gets slightly bent, so that the cage catches the spokes of the rear wheel when that final shift is made, or the cage rides close enough to the spokes that when they flex under extreme stress (and they do flex) they move enough to catch the cage.  At this point, the hanger is pretty much guaranteed to be bent, but I have a feeling that it may have been slightly out of alignment before this happened, as well.  Val

Epic fail on any bike part?  I can think of several—maybe there’s a pattern of vintagey stuff with way too many miles.  I snapped one of those fluted Campy posts right at the solid part, near the top.  Also broke a Mavic SSC bottom bracket almost in the middle, for no apparent reason other than age.  The bb only had about 20,000 miles on it, the post probably a lot more, lol.

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