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Chain plate cracking?

alp777alp777 Posts: 211
edited March 2010 in Workshop
I fitted a new chain on my winter bike about 2 months ago because the first one cracked like in the photo below. My current chain (pictured below) has done exactly the same thing. It was fitted correctly, is the correct length and none of the sprockets or chain rings are worn. I run a compact (50/34) with a 12/26 block on the back. Anybody have any ideas why this might be happening?



chain%20001.jpg

Posts

  • koppenbergkoppenberg Posts: 32
    That is a Sram chain,this is a big problem with Shimano first time seen on Sram? Something is going on very bad out there?
  • Monty DogMonty Dog Posts: 20,614
    How do you clean the chain? Some chains are susceptible to hydrogen-embrittlement due to them being cleaned in aggressive solvents, or perhaps there is a faulty batch out there?
    Make mine an Italian, with Campagnolo on the side..
  • will3will3 Posts: 2,173
    oh my, I just took out a link on my PC951 chain with exactly the same failure :?
    (though I had ridden 100miles with a strange clicking through the pedals, which turned out to be the bust link!)
  • balthazarbalthazar Posts: 1,565
    Great picture. It looks like the crack in the bottom side of the plate was completely through some miles ago, judging by the grime that's accumulated in it. The tiny distorted nub at the top right edge of the top crack implies that that area was the last soldier, so to speak.

    To my knowledge, these chains aren't known to be unreliable, so I'd guess simply that you've been unlucky, or that there's a faulty batch. Maybe try a different make next time? The same failure was reported with KMC a while back but I've not heard of anything recently. KMC are probably as common as any other among the bikies here.
  • alp777alp777 Posts: 211
    Monty Dog wrote:
    How do you clean the chain? Some chains are susceptible to hydrogen-embrittlement due to them being cleaned in aggressive solvents, or perhaps there is a faulty batch out there?

    I use GT85 and standard citrus chain degreaser.
    To my knowledge, these chains aren't known to be unreliable, so I'd guess simply that you've been unlucky, or that there's a faulty batch. Maybe try a different make next time? The same failure was reported with KMC a while back but I've not heard of anything recently. KMC are probably as common as any other among the bikies here
    This is the second chain it has happenned to the first chain was a Shimano.

    My next question is do i need a new chain or can i just replace the link?
  • keef66keef66 Posts: 13,123
    If the chain is still fairly new and close visual inspection reveals no other suspect plates you can just replace the one link. Push out both pins and insert a KMC missing Link or the SRAM jobby.
  • DomProDomPro Posts: 321
    That shouldn't be happening at all. It can only be a faulty chain so I would take it back to the shop, preferably for a refund or shimano chain instead.
    Shazam !!
  • redddraggonredddraggon Posts: 10,862
    I had a batch of KMC chains, and they all did this:

    3336041638_a8d04ab98e.jpg
    I like bikes...

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  • crankycrankcrankycrank Posts: 1,830
    Hmm. This is very interesting. I never heard of so many chains having cracked links until 10sp came around. Obviously this is not a rampant problem but with SRAM, KMC and Shimano all having a few failures like this I'm beginning to wonder if maybe the amount of metal used in narrow chains is getting a bit too thin and higher standards of quality control should be used. Again, I realise most people haven't had any problems but there are too many failures by too many mfrs to ignore IMO. Anybody have any insight on this??
  • will3will3 Posts: 2,173
    crankycrank wrote:
    Hmm. This is very interesting. I never heard of so many chains having cracked links until 10sp came around. Obviously this is not a rampant problem but with SRAM, KMC and Shimano all having a few failures like this I'm beginning to wonder if maybe the amount of metal used in narrow chains is getting a bit too thin and higher standards of quality control should be used. Again, I realise most people haven't had any problems but there are too many failures by too many mfrs to ignore IMO. Anybody have any insight on this??

    Um the 951 is a 9 speed chain.
  • jermasjermas Posts: 484
    Are you changing gear a lot under high load - when climbing. This is when chains are subjected to most stresses.
  • koppenbergkoppenberg Posts: 32
    The same things is happening on Shimano chains this year!!!

    KMC & Shimano-from same factory or sourcing same materials?
  • Monty DogMonty Dog Posts: 20,614
    AFAIK KMC do make some of the Shimano chains.
    Make mine an Italian, with Campagnolo on the side..
  • TheStoneTheStone Posts: 2,291
    Had exactly the same problem with a Shimano 6700 (new ultegra chain), after no more
    than 400km.

    Been using 10 speed for a long time without it happening before.
    exercise.png
  • andrew_sandrew_s Posts: 2,511
    crankycrank wrote:
    Hmm. This is very interesting. I never heard of so many chains having cracked links until 10sp came around. Obviously this is not a rampant problem but with SRAM, KMC and Shimano all having a few failures like this I'm beginning to wonder if maybe the amount of metal used in narrow chains is getting a bit too thin and higher standards of quality control should be used. Again, I realise most people haven't had any problems but there are too many failures by too many mfrs to ignore IMO. Anybody have any insight on this??
    I'd be inclined to blame the peening of the rivets (driving a punch into the end to expand it against the hole in the outer plate). It's probably a fairly critical process - expand too much and you overstress the chain plate so it cracks after a bit, don't expand enough and the rivet pops out. I'd guess that the problem surfaced at the same time as 10 speed because a new improved peening process was introduced for the 10 speed chains.

    Another point may be that there is more communication of the problem than there used to be, what with increased internet use and cheap digital cameras with good macro capability.
  • John.TJohn.T Posts: 3,698
    jermas wrote:
    Are you changing gear a lot under high load - when climbing. This is when chains are subjected to most stresses.
    +1 for this. Full power changes put large side loadings on the chain.
    My Fleet.
  • John.TJohn.T Posts: 3,698
    jermas wrote:
    Are you changing gear a lot under high load - when climbing. This is when chains are subjected to most stresses.
    +1 for this. Full power changes put large side loadings on the chain.
    My Fleet.
  • koppenbergkoppenberg Posts: 32
    Funny thing is-are you not meant to be changing gear at these times? :wink:

    I have seen this now on several bikes used by some Elite riders who do know what they are doing-One group of riders has seen 4 chains go within a short space of time on a ride!

    Never has the chain snapped at the joining link,or cracked here either.

    The max life of these chains when used in training is 800 kms,but they are getting replaced at 500 kms.
  • freehubfreehub Posts: 4,257
    John.T wrote:
    jermas wrote:
    Are you changing gear a lot under high load - when climbing. This is when chains are subjected to most stresses.
    +1 for this. Full power changes put large side loadings on the chain.

    My chains never had these problems due to changing gears like this.
  • kettrinboykettrinboy Posts: 613
    ive been using a SRAM PC951 chain on my winter bike for just over a year and 3200 miles and ive just had a look at it carefully and theres no signs of it cracking, perhaps as others have said a faulty batch has slipped out, in 10000 miles ive only had to replace the chain once, the OE Shimano HG50 lasted 6800 miles until a link plate split and then ive had this SRAM PC951 since with no bother so far
  • will3will3 Posts: 2,173
    Just had another look at my chain. seems it's worn past 1% dammit - only had it on about 3 months.
    Kettrinboy- when you say 'lasted' do you check for chain wear?
  • balthazarbalthazar Posts: 1,565
    Even though 1% wear is over the sensible limit for replacement, that limit is determined by sprocket longevity, not the durability of the chain itself. This kind of fatigue failure is unacceptable even for a heavily worn chain.
  • kettrinboykettrinboy Posts: 613
    yeah when the shimano HG50 chain broke it was around 1% worn measuring over 24 links with a vernier caliper, it didnt snap but i could hear and feel a clicking through the drivetrain and then found the split sideplate, the Shimano Ultegra chain on my Scott CR1 has done 6600 miles and is 0.75% worn so that shows that chains can last if they are cleaned and lubed every 100 miles or so, well thats what i do anyway and its worked so far on the chains ive used
  • will3will3 Posts: 2,173
    kettrinboy wrote:
    shows that chains can last if they are cleaned and lubed every 100

    That'd be cleaning it every other day :cry:
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