I rode for a little while longer then I should have with my old chain, so I replaced the old chain and cassette. But now when I ride in the big ring, the drivetrain makes a horrible sound and the chain falls from the big ring to the small ring. The teeth on the chainring are looking a bit shark-tooth like.

I don't know if this is related but I am using this new ceramic chain-lube.

I don't know if I have to re-adjust the derailleur as it seems to shift up and down properly.

2 Answers 2


At the point where the chainring teeth look anything like a sharktooth, they won't really work with a new chain without skipping and other issues. Even if it wasn't as extreme as that, it would still be accelerating wear on the new drivetrain parts. Replace the ring.

  • Correct - its hard to be sure without a photo, but if its description is "shark fin" then its worn. The old elongated chain was probably okay on the worn chainring, but the new one is functionally shorter on each link so only one or two teeth can take the whole chain load. The chain will wear faster if you don't change the chainring.
    – Criggie
    Commented Nov 1, 2017 at 0:39

Changing your chain before it wears beyond an acceptable limit prevents premature wear of the other parts of your drivetrain, which are typically more expensive to replace. If you bike a lot, invest in and learn how to use a chain wear gauge (usually less than 10 euro), or drop into your local bike shop and make friends!

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