Unusual (for me) chain failure

[Slioch]

Was doing some routine maintenance today with the bike up on the stand. Whilst slowly turning the cranks to check for any problems there was a slight "thunk" each rotation.

Closer inspection showed this

Not sure how long this has been going on for, so I guess I'm lucky that the chain didn't fail on me whilst out on a ride. I'm surprised that I didn't "feel" it whilst riding.

It's the first time I've experienced a chain doing this. Has anybody else had this happen to them?

 

[HLaB]

Yip, its happened to me a few times. Touch wood it only happened on less well maintained 8speed chains. I've never had it happen with my 10 and 11 spd chains.

 

[Slioch]

It's a 9 speed chain, which is about 50% worn according to my measuring tool.

 

[Yellow Saddle]

It is a crack in the outer sideplate. This happens when the heat treatment goes wrong or, the plating goes wrong. It could happen on just one plate due to a little malfunction where one plate doesn't go through treatment or, skips the quencing. It could also happen where an entire batch goes wrong such as when there's bad pickling in the plating process. I have one chain in my arsenal of chain maladies where just about every plate has such a crack. It only happens on the sideplates, even though inner plates can also get the wrong treatment. This is because of the expansive force of the rivet which only acts on outer plates.

It has nothing to do with wear and use.

 

[sleuthey]

I had it 3 months ago with a KMC nine speed chain. It got a bit clicky one ride then snapped when I rode up a ramp.

 

[silva]

Which brand and model chain is this?

 

[Slioch]

'Tis a 9 speed KMC chain that failed.

Interestingly (or not!) when trying to source a replacement earlier today, both Wiggle and Chain Reaction were out of stock of KMC 9 speed chains. And when I tried alternative sources which did have them in stock (SJS Cycles/Ebay/Amazon) they were selling at a more "premium" price - I.e. supply & demand effect. 9 speed Shimano chains though were available everywhere.

Are 9 speed chains falling out of fashion, or are KMC having production problems and the main on-line retailers are switching provider?

 

[the_mikey]

Are 9 speed chains falling out of fashion, or are KMC having production problems and the main on-line retailers are switching provider?

KMC have recently rationalized their range of chains, meaning they still sell 9 speed chains but no longer offer a multitude of different versions, it's possible old stock is being flagged up as being obsolete or of unknown availability, and you could be overlooking the new KMC chain in your searches...

 

[cyberknight]

cant say i have ever had an issue with 8 or 10 speed and i generally use kmc

 

[Nigelnightmare]

I had exactly the same thing last year!
Interestingly enough it was also a 9 speed KMC chain, Repaired using a quick link.
It broke again a week later (same thing, different link).
A *few* of the local kids (10-15Yr olds) came to me with the same problem (Also KMC chains)!

Now I use "Connex" by wippermann.
*It's amazing how popular you get when you help out and teach them how to work on their own bikes.
Saw a couple of the older ones helping the younger kids with their bikes this summer.

 

[Slioch]

Hmmm. That's three people on this thread who have had a 9 speed KMC chain fail like this (strokes beard and looks thoughtful).

 

[Ajax Bay]

Go SRAM then:
https://www.wiggle.co.uk/sram-pc951-9-speed-chain/