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New Chain/New Cassette

  • 28-03-2012 12:38pm
    #1
    ROK ON
    Closed Accounts Posts: 6,831 ✭✭✭


    I took the good bike down from the attic last night and fitted a new chain and cassette.

    The measured the chain like normal and then added two links (as normal).

    The chain keeps skipping in the middle of the cassette. Fine high and low, but jumping all over in the middle (whether in the big or small front ring).

    This has only ever happened to me on an old chain/cassette combo (ie a sign that the chain has stretched).

    Can I fix this thru gear indexing, or is it likely that I have cut the chain too long?


Comments

  • #2
    cdaly_
    Registered Users, Registered Users 2 Posts: 6,440 ✭✭✭cdaly_


    Skipping gears as opposed to slipping off the teeth? Bent hanger is a likely culprit. I'm currently getting something like that on mine, no amount of indexing will fix it...


  • #3
    ROK ON
    Closed Accounts Posts: 6,831 ✭✭✭ROK ON


    cdaly_ wrote: »
    Skipping gears as opposed to slipping off the teeth? Bent hanger is a likely culprit. I'm currently getting something like that on mine, no amount of indexing will fix it...


    No its slipping. When a middle gear is chosen it wont stay on that gear, but wont immediately drop down to the next either. Keeps jumping so to speak, and eventually slips down to the next one.


  • #4
    CramCycle
    Moderators, Sports Moderators Posts: 25,917 Mod ✭✭✭✭CramCycle


    Is it possible the tension screws need to be adjusted slightly?


  • #5
    ROK ON
    Closed Accounts Posts: 6,831 ✭✭✭ROK ON


    CramCycle wrote: »
    Is it possible the tension screws need to be adjusted slightly?


    Maybe, but in which direction.

    It strikes me that I have following options (none of which are appealing for someone that is not a fan of DIY and has no patience).

    Fiddle with gear adjuster, up and down.
    Fiddle with tension screws * 2 both up and down.

    That gives too many possibilities for me to make things even worse, and only a slim chance of actually fixing the issue.


  • #6
    C3PO
    Registered Users, Registered Users 2 Posts: 3,814 ✭✭✭C3PO


    ROK ON wrote: »
    Maybe, but in which direction.

    It strikes me that I have following options (none of which are appealing for someone that is not a fan of DIY and has no patience).

    Fiddle with gear adjuster, up and down.
    Fiddle with tension screws * 2 both up and down.

    That gives too many possibilities for me to make things even worse, and only a slim chance of actually fixing the issue.

    I'll have a go at most things on the bike but gear indexing/adjustment always seems more like an art than a science ...... I'd go to my trusty LBS!


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  • #7
    CramCycle
    Moderators, Sports Moderators Posts: 25,917 Mod ✭✭✭✭CramCycle


    Turn the bike upside down and look at the position of the derailleur in both large and small cog, making sure you change the front gears as appropriate as well. Just because it is not popping out in the large/small cog does not mean it does not need to be adjusted. This should give you an idea of which way to adjust if it is necessary.

    I would only do this after checking everything else though, as if it was fine before it seems strange it would suddenly need a change.


  • #8
    Tayto2000
    Registered Users, Registered Users 2 Posts: 597 ✭✭✭Tayto2000


    Obvious one, but are you sure you got the right cassette for your shifters? A long time ago a certain now defunct bicycle shop sold me a new machine with 8 speed shifters and a 7 speed cassette, I didn't know anything about bikes and assumed the problems such as you are describing were normal (I used to 'trim' the shifter with a bit of pressure to complete shifts). A different LBS spotted the problem when I had left it in for a service.


  • #9
    lescol
    Registered Users, Registered Users 2 Posts: 648 ✭✭✭lescol


    Likely to be cable stretch. Pop the bike on the turbo, manually turn the cranks while gradually adjusting the cable tensioner until you hit the sweet spot. Then double check that all gears are available to you. Leave the limit screws alone!


  • #10
    Chips Lovell
    Moderators, Politics Moderators, Sports Moderators Posts: 24,269 Mod ✭✭✭✭Chips Lovell


    Limit screws shouldn't need to be adjusted once a deraileur has been fitted.

    What's more likely is that the indexing is out due to cable stretch. That's fairly simple to get right once you follow instructions.


  • #11
    Mycroft H
    Registered Users, Registered Users 2 Posts: 9,313 ✭✭✭Mycroft H


    Watch this, its the best video going about on it.



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  • #12
    Lumen
    Registered Users, Registered Users 2 Posts: 31,245 ✭✭✭✭Lumen


    The best time to adjust limit screws is when there's no chain on the bike and no cable tension (cable end popped out of the stop). You can then move the derailleur by hand and make sure the jockey wheel aligns with the end sprockets at the limits.


  • #13
    Mycroft H
    Registered Users, Registered Users 2 Posts: 9,313 ✭✭✭Mycroft H


    BX 19 wrote: »
    Watch this, its the best video going about on it.



    Limit screws are dead handy to adjust, its no harm turning them slowly to make sure they are correctly adjusted. They can vibrate loose over time and if your hanger is slightly out of alignment, the two of them can combine (worst case senario :D) to throw the chain off the top cog and eat your spokes. Loctite blue if they have a habit of turning by themselves.

    However, the limit screws will not affect the middle of the range shifting, that's down to index adjustment.


  • #14
    Mycroft H
    Registered Users, Registered Users 2 Posts: 9,313 ✭✭✭Mycroft H


    Lumen wrote: »
    The best time to adjust limit screws is when there's no chain on the bike and no cable tension (cable end popped out of the stop). You can then move the derailleur by hand and make sure the jockey wheel aligns with the end sprockets at the limits.


    +1, its simplicity itself to do it then. I usually check it when I have the chain off to clean.


  • #15
    irishmotorist
    Closed Accounts Posts: 1,268 ✭✭✭irishmotorist


    I'd be inclined to agree with the cable stretch theory. I find when my gears are acting maggoty, it's often down to the cable and it just needs to be replaced.


  • #16
    Mycroft H
    Registered Users, Registered Users 2 Posts: 9,313 ✭✭✭Mycroft H


    irishmotorist wrote: »
    I'd be inclined to agree with the cable stretch theory. I find when my gears are acting maggoty, it's often down to the cable and it just needs to be replaced.


    Is it not the housing rather then the cable itself stretching ?


  • #17
    ROK ON
    Closed Accounts Posts: 6,831 ✭✭✭ROK ON


    Thanks for all of the advice.

    I think I have found this issue. When I fitted the new chain, the link did not close completely, so the chain was only being held together by half a link so to speak.

    Removed link and fitted a quick link.

    Have had the bike on the turbo and have moved through all of the gears several times.

    So while I have wasted 2 hours of work, it would seem as if everything is ok.

    Cable stretch - I thought it might be that - but the cables were replaced last April, and this bike was used only a handful of times over the summer and it has been in the attic since September.


  • #18
    Mycroft H
    Registered Users, Registered Users 2 Posts: 9,313 ✭✭✭Mycroft H


    ROK ON wrote: »

    So while I have wasted 2 hours of work, it would seem as if everything is ok.


    Don't think of it of a waste, your more the wiser the next time round :D


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