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    What could be the possible reasons for this??

    I am using shimano 105 groupset. I had to replace the RD and chain. Since it is a second hand bike.

    I upgraded the 11-30 cassette (Shimano) to 11-32 Cassette (SRAM). And chain was KMC-X11. After 4500 km of ride the chain broke. (One of the link was broken) I removed the broken link and used the chain for another 300km. But it broke again.

    So i replaced it with Shimano CN-HG601-11 chain.

    I have only used this for, like 6 ride (around 350km). But the chain broke again. When i checked the broken chain i could see multiple cranks on different links.

    What could be the possible reasons for this?

    My observations:
    1.Most of the cracks are on the same side of the chain
    2.First time KMC chain link broke (twice) on the same side
    3. The chain broke on a small climb, may be when i can using 3rd 4th or 5th cassette ring
    4.Previous day when i was washing and lubing the chain i didn't noticed any cracks

    by pa_ava_m

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    17 Comments

    4. semyorka7 on

      >I have only used this for, like 6 ride (around 350km). But the chain broke again. When i checked the broken chain i could see multiple cranks on different links.

      first question: where’d you buy it?

      Amazon? Aliexpress? Or a real bicycle retailer?

    6. BrycenWilliams on

      Is it an 11 speed? having mixed chain/cassette causes issues due to sram and Shimano sprockets having different widths

    7. Antti5 on

      It could be a fake chain, as these are not uncommon. I wouldn’t buy chains from e.g. Amazon for this reason.

      But even genuine chains sometimes have cracked side-plates, evidently due to failed heat-treating in the manufacturing process. There was an epidemic of failing SRAM chains some years ago.

    8. TheLandTraveler on

      KMC is garbage.
      I bought one of their most expensive chains directly from their website and it immediately started shedding its coating and then snapped after a few months. Contacted them and they basically made it impossible to get any help and pretty much told me to get bent.

    12. Clbrosch on

      Simple green will also make a chain brittle. I have only run a few kmc chains but they were 9 speed

    14. 510519 on

      I had a sram do this. I think during the pandemic there was some bad steel in the supply chain or a problem with the heat treating process. I got mine at a LBS and when I told them about it they said they’d never seen this happen before.

    15. -DangerNoodle- on

      Working in a bike shop and have seen this a handful of times over the past couple of years with no obvious explanations. Someone previously mentioned bad steel/heat treating and this is the only logical explanation imo.

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