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Gear Indexing Conundrum

DezzaDezza Posts: 155
edited November 2012 in Workshop
Hi all

Sorry, this is another gear indexing based problem. I've used the search function and found similar issues but not quite what i'm after.

I have a 4 month old bike with ultegra front/rear mechs and 105 cassette. I can get it to index smoothish on the workbench using the barrel adjuster and a few swear words. Yet, when I then take it out for a ride, shifting up a gear (smaller sprocket) needs two clicks. The first grinds then the second skips a sprocket (double shift), this means i have to then drop down a gear. So the first click is like 0.5 change and the second 1.5 changes.

Down shifting is fine.

I'm at a loss to what to do next. Shifting was working okish before I adjusted it, but I was getting a regular 'ticking' because the indexing was slightly out. Is this due to my own incompetence or could it be something more drastic like a misaligned rear mech, bent drop outs or dodgy freehub unit?

Dezza.

Posts

  • As the bike is only 4 months old.. unlikely (unless you've dropped it / kicked it / crashed it) to have a misaligned rear mech or bent dropouts.

    when you are trying to set up the indexing - have you made sure that you've tightened the cable? it will stretch and cause the indexing to go off.

    http://www.parktool.com/blog/repair-hel ... derailleur

    The link above should have all the info you'll need to start from scratch as it were.
  • DezzaDezza Posts: 155
    Thanks for the link, looks very helpful. So you think this is beyond a simple barrel adjustment then? It seems a bit strange that I can get it indexing on the bench but it goes mental on the road.
  • the barrel adjuster is really only there to take up a little slack and make minor adjustments allowing for smooth indexing.. the cable stretches through use and the barrel adjusters aren't meant to compensate for this. I would read through the park tools page and follow their instructions. you should find that solves the issues. Also make sure that you read the manual for your rear derailleur and check that the cable is passing though the clamp on the derailleur in the correct path - get that wrong and each click will pull the derailleur the wrong distance making it impossible to get accurate indexing. i would check this before starting to adjust the indexing.
    let us know how you get on.
  • drlodgedrlodge Posts: 4,825
    If gear changing is inconssistent, which appears to be the problem here, I would first check that the cable is moving freely as the only thing that's pulling the cable tight is the spring on the RD. If the spring is quite weak, the cable can easily stick. You might also check that the "B" screw is adjusted properly so that the jockey wheels are no too far from the cassette.
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  • DezzaDezza Posts: 155
    Cool.. thanks for the pointers chaps!

    I probably wont get the chance to give this a go until after the weekend so I'll let you know how I get on when I do.
  • smidsysmidsy Posts: 5,273
    the barrel adjuster is really only there to take up a little slack and make minor adjustments allowing for smooth indexing.. the cable stretches through use and the barrel adjusters aren't meant to compensate for this. I would read through the park tools page and follow their instructions. you should find that solves the issues. Also make sure that you read the manual for your rear derailleur and check that the cable is passing though the clamp on the derailleur in the correct path - get that wrong and each click will pull the derailleur the wrong distance making it impossible to get accurate indexing. i would check this before starting to adjust the indexing.
    let us know how you get on.

    Oh yes they are. The barrel adjuster (the thumb turn on the rear mech) is the only way to compensate for cable stretch (until it runs out) then it's undo cable, return adjuster barrel to its minimum (all the way clockwise) and re-install or fit new cable.

    Sounds to me like cables are sticking, are the inners and outers still OK - no stragly bits or cuts, caked with dirt etc.

    Try cleaning and lubing the cables.

    If the gear moves correct for one click then it should move correct for all of them, that's what indexed gears means.

    Do not touch the high and low limit adjustment screws either, these do not affect indexing in any way, only mech limits.
    Yellow is the new Black.
  • centimanicentimani Posts: 467
    Smidsey has it about right, I'd check the following (mostly covered by himself)...
    Cables routed correctly, have you connected, then disconnected any ?..I've routed a cable incorrectly from the rear derailleur barrel adjuster to the clamp once, and it caused a mare when trying to set it up.
    Cables free ? No stickiness.
    Have you had the wheel out ?...had this before as well. Tried in vain to index gears on an old bike, struggled like hell and couldn't understand why. Had the wheel out for another reason, back in...and away it went, set up like a dream. Must have been slightly skewed

    If the indexing worked well before, as smidsey says, don't touch the limit screws, if you do so unnecessarily, you'll end up in a worse pickle and have to start right from scratch (which actually isn't a bad thing, but you have more to think about)
  • andy_wrxandy_wrx Posts: 3,396
    Yeah, like Smidsy says, the barrel adjusters are designed exactly for cable stretch

    (note that the wire strands don't stretch as such, they're not springs, but the cable is multiple strands all wrapped around oneanother - as you first use a new bike, they'll move slightly relative to oneanother and bed-in, so after a few weeks the cable will have stretched just a fraction and the adjuster allows you to take-up that little bit of slack)

    As Smidsy also suggests, it could be a bit of muck in the cable - particularly that tight rear loop at the back of the bike.
    Get the bike in your lowest gear, on the biggest cog at the back, then click the shifter all the way to top gear without turning the pedals - the cable will go slack. You can now unclip the cable from its guides at the back of the bike and slide the outer along the cable. Check it's clean and lubricate a bit with chain oil, then reassemble.

    If it were an older bike, it would be possible that the cable itself is fraying at the other end, in the shifter.
    With the cable loose as just described, if you pull the brake on slightly so the lever is part-open and push the loosened inner cable up the outer towards the shifter, you should be able to poke the 'plum' on the end out of its recess in the shifter. If you have loose strands poking out of the plum, time for a new cable.

    But if it worked before you, ahem adjusted it (started fiddling with it :D - never mind, got to learn sometime), it probably is just adjustment.

    Best is to set the indexing up from the middle of the cassette, i.e. so it shifts cleanest from 5th to 6th and back again.
    If you do it at one of the ends (1st to 2nd, or 9th to 10th) then any issues are magnified at the other end of the cassette
  • DezzaDezza Posts: 155
    Ok, ive cleaned and chain lubed the rear outer cable. With the bike on the stand ive adjusted, i mean fiddled :P with the barrel adjuster and it indexed ok. However, the shift was really harsh (seemed to jump out of the sprocket - if you know what I mean?). The double shift had gone.

    I then gave it a spin on the rollers and the shift action felt really hard (cable too tight?), i could feel it through the bike. The shift also took about half a sec to catch then moved over - a slight delay. If i rotate the adjuster anti-clockwise (looking from behind bike), the change softens but the double shift reappears.
  • deswellerdesweller Posts: 5,175
    Take a look inside the shifter. Cables can sometimes come to pieces quite quickly; not often, but it does happen
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  • drlodgedrlodge Posts: 4,825
    A hint for checking RD shifter operation, this is what I do to ensure there is proper alignment of the RD with the cassette.

    - Put bike on stand and take the chain off
    - Move the RD by changing gear, then pull the RD so that the top jockey wheel is touching the cassette. The top jockey wheel should be in exact alignement with the sprocket that should be engaged
    - this way, its easy to see how good the alignment is, and you can adjust the barrel adjuster and stop screws until you're satisfied.
    - Once the chain is back on and you test ride it, gear chaning should be perfect. If not, just make 1/4 turns on the barrel adjuster
    - If alignment is not good on all sprockets, when changing up and down, then investigate the problem. If for example, changing to larger sprockets is fine, but smaller sprockets the RD lags, then the inner cable is probably getting caught.
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  • smidsysmidsy Posts: 5,273
    drlodge wrote:
    A hint for checking RD shifter operation, this is what I do to ensure there is proper alignment of the RD with the cassette.

    - Put bike on stand and take the chain off
    - Move the RD by changing gear, then pull the RD so that the top jockey wheel is touching the cassette. The top jockey wheel should be in exact alignement with the sprocket that should be engaged
    - this way, its easy to see how good the alignment is, and you can adjust the barrel adjuster and stop screws until you're satisfied.
    - Once the chain is back on and you test ride it, gear chaning should be perfect. If not, just make 1/4 turns on the barrel adjuster
    - If alignment is not good on all sprockets, when changing up and down, then investigate the problem. If for example, changing to larger sprockets is fine, but smaller sprockets the RD lags, then the inner cable is probably getting caught.

    Do not do this. The limit screws will not affect indexing in the slightest. They simply ensure that the rear mech does not over shift either extreme of the cassette. Once that is correct and set it does not need touching.

    Indexing is purely down to cables. Tension, routing, condition, lubrication etc.
    Yellow is the new Black.
  • drlodgedrlodge Posts: 4,825
    smidsy wrote:
    drlodge wrote:
    A hint for checking RD shifter operation, this is what I do to ensure there is proper alignment of the RD with the cassette.

    - Put bike on stand and take the chain off
    - Move the RD by changing gear, then pull the RD so that the top jockey wheel is touching the cassette. The top jockey wheel should be in exact alignement with the sprocket that should be engaged
    - this way, its easy to see how good the alignment is, and you can adjust the barrel adjuster and stop screws until you're satisfied.
    - Once the chain is back on and you test ride it, gear chaning should be perfect. If not, just make 1/4 turns on the barrel adjuster
    - If alignment is not good on all sprockets, when changing up and down, then investigate the problem. If for example, changing to larger sprockets is fine, but smaller sprockets the RD lags, then the inner cable is probably getting caught.

    Do not do this. The limit screws will not affect indexing in the slightest. They simply ensure that the rear mech does not over shift either extreme of the cassette. Once that is correct and set it does not need touching.

    Indexing is purely down to cables. Tension, routing, condition, lubrication etc.

    Er, yes the limit screws will affect indexing if they don't allow sufficient movement. However I agree that as long as they are not restricting movement, they won't affect shifting. Good practice, is once indexing is working well, shift to the largest sprocket and then gently press inwards on the RD. It should not move to touch the spokes, if it does then adjust the limit screw to stop it moving any more than it should.
    WyndyMilla Massive Attack | Rourke 953 | Condor Italia 531 Pro | Boardman CX Pro | DT Swiss RR440 Tubeless Wheels
    Find me on Strava
  • zx6manzx6man Posts: 1,092
    And...take it to a shop for a tenner :-)
  • smidsysmidsy Posts: 5,273
    drlodge wrote:
    smidsy wrote:
    drlodge wrote:

    .

    Er, yes the limit screws will affect indexing if they don't allow sufficient movement. However I agree that as long as they are not restricting movement, they won't affect shifting. Good practice, is once indexing is working well, shift to the largest sprocket and then gently press inwards on the RD. It should not move to touch the spokes, if it does then adjust the limit screw to stop it moving any more than it should.

    No they don't, you are mixing up two issues.

    If the mech does not allow sufficient travel THAT is a travel issue not an indexing one.

    Indexing is the process that allows the chain to move from one sprocket to the next. This requires a set amount of cable pull per click and has nothing to do with the limit screws.
    Yellow is the new Black.
  • OuijaOuija Posts: 1,386
    Sounds like cable binding, as is usually the case when the derailleur jumps to some gears fine but not others. If the cable was too tight or too loose you'd find the derailleur doesn't want to jump properly up ALL the gears or down ALL the gears, not just one or two. If the shifters feel stiff to operate it's usually and indication of inner cable not sliding freely through the outer cable. If your dérailleur is not a direct pull design (which it looks like it isn't) then it's usually in that tight curve of cable that goes from the frame to the back of the dérailleur. One of the best upgrades to smooth out that problem is to ditch that loop of cable and use a avid rollermajig instead (Rose bikes also make them too, called the easy roller) which converts the derailleur into direct pull.
    561068_1.jpg
  • smidsysmidsy Posts: 5,273
    Ouija wrote:
    Sounds like cable binding, as is usually the case when the derailleur jumps to some gears fine but not others. If the cable was too tight or too loose you'd find the derailleur doesn't want to jump properly up ALL the gears or down ALL the gears, not just one or two. If the shifters feel stiff to operate it's usually and indication of inner cable not sliding freely through the outer cable. If your dérailleur is not a direct pull design (which it looks like it isn't) then it's usually in that tight curve of cable that goes from the frame to the back of the dérailleur. One of the best upgrades to smooth out that problem is to ditch that loop of cable and use a avid rollermajig instead (Rose bikes also make them too, called the easy roller) which converts the derailleur into direct pull.

    This. As stated previously if the gear shifts one step fine (up and down) it is not an indexing issue, as each jump is the same, so if it works once it's indexed.

    Cables my boy, cables. Routing or condition, has to be.
    Yellow is the new Black.
  • Monty DogMonty Dog Posts: 20,614
    Sounds like a rubbish install - could be down to gear hanger alignment, poor cable install / incorrect lengths or clamping the cable on the wrong side of the screw. I'd suggest an experienced mechanic takes a look.

    As for 'cable stretch' - it doesn't - but outer cables and ferrules do settle into the frame stops thus creating the impression that the inner has got longer.
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  • DezzaDezza Posts: 155
    After a few weeks of being away I was able to have a bit of a fiddle with the bike. Still couldn't remedy the problem.

    I gave up and my LBS sorted it for a tenner. Apparently the hanger was a tad out and it needed more than a newb to tweak the indexing. Well at least I tried! Thanks to all those who advised.
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