Help adjusting gears. Could it be new chain length?

Discussion in 'Bicycle Mechanics and Repairs' started by RhythMick, 16 Jul 2012.

  1. RhythMick

    RhythMick Über Member

    Location:
    Barnsley
    Recently bought Yeti Arc 2nd hand. Unfortunately the chain broke first ride out. Now replaced that with SRAM 951.

    Think I've got the chain length right using the Park Tools web page on the matter. Biggest front cog 44, biggest rear 32, chainstay 16.9 inches. Formula calcs that as needing 54 inches which I have on (inc the master link). Attached pics show it in small/small and large/large gear combos. Looks right to me but as I've never changed a chain before I'm checking here.

    Turned upside, or on the stand, the indexing works perfectly in all gear combinations. sweet as. On the bike though (under load) it's jumping gears when on the smallest front cog. Other two fine.

    I've been through the process several times. Always same result. I wondered if the chain length could be causing it if it's not quite right (but I do think it's right).

    BIGGEST COGS
    uploadfromtaptalk1342473231078.jpg

    SMALLEST COGS
    uploadfromtaptalk1342473319624.jpg
     
  2. OP
    OP
    RhythMick

    RhythMick Über Member

    Location:
    Barnsley
    The swift-sighted among you will notice the presence of TWO master links.

    :blush:

    Having never changed a chain before I went through the process but assumed I'd got it wrong when I noticed the skipping. I wrongly thought the chain was too long and was jumping when the chain was at it's slackest. So I shortened it. That didn't solve the problem and I later realised it was skipping gears, not chain slipping. I rescued the 3 links and rejoined them with a master. The whole thing measures 54" ... I checked several times.
     
  3. Perfect chain length (and very awesome bike BTW) but the old chain was allowed to get so old that it trashed the cassette sprockets. Thats why its jumping. The fact that the chain broke is the very best evidence that it was effed.
     
  4. OP
    OP
    RhythMick

    RhythMick Über Member

    Location:
    Barnsley
    Bugger. If you don't mind me saying. Likely new cassette then. But thanks for the response.
     
  5. Can i just say..... Those pedals are an abomination.
     
  6. OP
    OP
    RhythMick

    RhythMick Über Member

    Location:
    Barnsley
    Actually likely cassette AND cogs I assume.
     
  7. HovR

    HovR Über Member

    Location:
    Plymouth
    Please.. let's try not to start another pedals argument. :rolleyes:
     
  8. OP
    OP
    RhythMick

    RhythMick Über Member

    Location:
    Barnsley
    oh yeah no question. Temporary until my Wellgo MG-1s arrive.
     
  9. OP
    OP
    RhythMick

    RhythMick Über Member

    Location:
    Barnsley
    Looking at this ... Seems a decent price ...

    http://www.chainreactioncycles.com/Models.aspx?ModelID=5213

    Another job I've never done before, but I'd prefer to tackle it if possible. Doable ? Or just get it to a proper mechanic.
     
  10. OP
    OP
    RhythMick

    RhythMick Über Member

    Location:
    Barnsley
    Forget that ... It's a Shimano Deore XT set up.
     
  11. OP
    OP
    RhythMick

    RhythMick Über Member

    Location:
    Barnsley
    Do I need to replace the whole chainset including cranks or can the cogs be replaced?
     
  12. guitarpete247

    guitarpete247 Just about surviving

    Location:
    Leicestershire
    I'd say the outer chainring needs replacing, at least. Some of the teeth look a little shark tooth like.

    You should be able to but just the chainrings if they bolt on. If riveted of the whole lot including crank arms. But you can keep the pedals :whistle:.
     
  13. HovR

    HovR Über Member

    Location:
    Plymouth
    With it being a Deore crankset, I imagine the chainrings are removable, meaning you will be able to replace just the rings and keep your cranks - Although it is hard to be 100% by looking at the pictures. The four silver circle things on the largest chain ring should in fact be an allen key style bolt to remove the medium and large chain ring. The small chain ring should have a similar fixing mechanism.

    Regarding changing the cassette - It is an easy job to do at home, however you will require a chain whip and cassette lock-ring tool if you do not have one already. YouTube is your friend - Search it for video tutorials.
     
  14. Cubist

    Cubist Still wavin' Moderator

    Location:
    Ovver 'thill
    Just do the cassette for the time being. Those rings look ok. You can get separate chainrings no probs. the cassette change is a simple task, as long as you hae the right tools.
     
  15. OP
    OP
    RhythMick

    RhythMick Über Member

    Location:
    Barnsley
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