How can you tell when the chain's/cassette's/chainring's worn out?

Discussion in 'Bicycle Mechanics and Repairs' started by Maz, 17 Dec 2007.

  1. Maz

    Maz Legendary Member

    First off, by 'cassette' I mean the cogs on the rear wheel (don't know if that's the right word).

    what are the tell-tale signs of wear? if you catch it early enough, can you get away with only having to change the chain?

  2. fossyant

    fossyant Ride It Like You Stole It!

    South Manchester
    If you put a new chain on and the chain 'jumps' then the cassette is worn - that's the main indicator of a knackered cassette.

    Usually the teeth on the cassette will start to look like a shark's fin, although it's not always easy to tell as the tooth profiles vary on hyperglide casettes.

    You'll most likely wear out specific sprockets, but it's near on impossible to buy single sprockets these days - so a whle new casette it is.
  3. OP

    Maz Legendary Member

    Many thanks, fossyant. I'll keep an eye out for any 'shark's fins' that start to develop.
  4. andygates

    andygates New Member

    As a rule of thumb with modern systems that are reasonably well maintained, you get about 2500 miles from a chain, 5000 from a cassette and 10000 from a chainring. Ish. The filthier you are, the less long they last.
  5. Stick on a Giant

    Stick on a Giant New Member

    Maz, if you change the change reasonably frequently you may get 3 chains use out of one cassette. I think the chain is considered worn when it measures over 12.25 inches for 12 links (I think, and apologies to the pedants for mixing imperial and metric). As always, I'm sure Sheldon Brown will offer guidance - don't have the actual link but good old Google...
  6. goo_mason

    goo_mason Champion barbed-wire hurdler

    Leith, Edinburgh
    Here's a photo of my front chainrings when I took them off to replace them. The large outer ring's teeth are in pretty good nick, but you can see how worn the middle ring's teeth are - showing fantastic shark's teeth wear !

  7. OP

    Maz Legendary Member

    @goo_mason...I see what you mean. Did the teeth on the middle ring used to have flat tops like those on the largest ring?

    Also, the slopes on the left of the 'peaks' seem slightly gentler than those on the right - like a shark's. Or is that just my eyesight playing tricks?

    Thanks for the picture.
  8. OW!
  9. andrew_s

    andrew_s Guru

    When the chainring teeth get like that, the chain sits up on them so you can see daylight between the chain and chainring

    His jockey wheel was even worse - you could see daylight through that too.
  10. goo_mason

    goo_mason Champion barbed-wire hurdler

    Leith, Edinburgh
    Mine were getting like that too, and I was about to replace them when I had my icy fallings-off last week and knackered the derailleur. I got a new one at a sale price (£16 - SRAM SX4), which was good considering it was going to cost me £8 plus p & p for just the jockey wheels !
  11. I feel sick.
  12. ash68

    ash68 New Member

    looks like you got ya monies worth out of that chainring :becool:
  13. goo_mason

    goo_mason Champion barbed-wire hurdler

    Leith, Edinburgh
    Oh dear. Get well soon ! ;)
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