I want to know if my cassette is worn. How can I tell as when I change gear it looks like the chain rides ontop of the sprockets rather than connect with them properly. I had to change the chain not long ago if that helps.

  • 1
    Without numbers this is impossible to answer. Do you have ideas of how much mileage everythig has done? Photos might help too
    – Criggie
    Nov 2, 2021 at 3:10
  • Does it shift properly? Are you sure the rear derailleur is properly aligned?
    – Michael
    Nov 2, 2021 at 8:04
  • 2
    " I had to change the chain not long ago if that helps." If this was due to excessive chain wear, the worn chain may have prematurely worn the cassette. Sometimes when a new chain is put onto a worn drive train, one will experience chain slipping, especially under load. The chain riding higher than normal may be a prelude to this slipping and implies a worn cassette
    – Jeff
    Nov 2, 2021 at 11:36
  • 1
    Pictures will allow you to get much more specific help. You say the chain "rides on top sprockets" which could also be the wrong size of chain or the deraileur out of alignment.
    – DWGKNZ
    Nov 2, 2021 at 12:03

2 Answers 2


If you waited too long before replacing your chain, your cassette needs replacement. The cogs on your cassette wear with your chain, and as your chain stretches, the valleys between the teeth of a cog will widen. Your most-frequently used cogs will exhibit the most wear. If you have recently replaced your chain with the correct spare, and this is a new problem, then replace your cassette with a new one. Keep your new chain clean and lubricated, and monitor chain wear with a quality chain checker. If the chain wears to stretch greater than 1% of it’s overall length, replace.


A crude way to judge the wear on cogs and chains is to grasp the chain at the back of the cog and attempt to pull it backwards. The distance you can pull it away from the cog is a measure of chain and/or cog wear (depending on which has more wear).

This works even better when judging chainring wear.

  • i think this answer, while imho correct, would benefit if you could state how many millimeters the chain may be pulled away before the parts should be considered worn
    – Burki
    Nov 18, 2021 at 10:12

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