105 Indexing Problem

herb71
herb71 Posts: 253
Hi, have a problem with my RD indexing. Have followed all of the set up guides, but cannot get the rear to index properly up and down.

Set up is Shimano, 105-5700, 10 speed.

Have fitted a new chain, gear shifter cable and cassette and the issue persists.

I can adjust it so it runs cleanly up the cassette, but then wont index back down. If I adjust tension so it indexes down the cassette, it wont go back up.

The new cable seems to pull properly and there is no undue friction. Any ideas? Worn RD? Worn brake-shifter? At my wits end with this.

Comments

  • webboo
    webboo Posts: 6,087
    Bent gear hanger
  • herb71
    herb71 Posts: 253
    Hi Webboo, I should have added, I have checked the gear hanger and its spot on. There is play in the RD, but I am not sure how much is normal, so I need to look at some mates bikes when I get the opportunity, to compare.
  • arlowood
    arlowood Posts: 2,561
    herb71 said:



    I can adjust it so it runs cleanly up the cassette, but then wont index back down. If I adjust tension so it indexes down the cassette, it wont go back up.

    By "running cleanly up the cassette" I am presuming you mean shifting from the smallest cog to the largest. If that is the case, it means that you have applied enough tension to the shifter cable for it to counter-act the resistance of the RD coil spring that controls the position of the hanger. Once you've reached the largest cog and flick the inner paddle to move back "down" the cassette to the smallest cog, then the derailleur coil spring should be strong enough to push the hanger across smoothly as it moves from cog to cog.

    If this is not happening then one explanation is that you have too much tension on the shifter cable or secondly, that there is something obstructing the smooth release of the cable. A third possibility is that the coil spring on the derailleur is knackered and does not have enough strength to push the hanger back smoothly to its default position.

    If I were you, I'd revisit the cable routing and double check that there is nothing obstructing or fouling the cable. Detach the cable from the derailleur and release it from the shifter and try pulling it back and forward. If you can get any lubricant into the cable outer then this should help.

    If the cable appears to be OK then I'd concentrate on the derailleur. Either the coil spring is Kaput or maybe it just needs a good clean and soaking to allow it to work as it should
  • herb71
    herb71 Posts: 253
    edited November 2020
    The cable moves freely. The inner is also new.

    If I set the tension on the barrel adjuster so the chain just moves one position (say smaller to larger), when I then click the inner paddle, it wont drop down again. If I back of the tension so it just drops down (large to small), it wont index back up.

    It can work smoothly across all 10 gears, but in one direction only.

    On the point of binning the lot and buy a new bike!
  • david37
    david37 Posts: 1,313
    is there any reason why you havent changed the cable outers?
  • herb71
    herb71 Posts: 253
    Hi David, no reason, other than there does not seem to be any issues at the cable that I can see. The new cable moves freely through the old outers. I didn't want to have to get new bar tape. I am going to look at my sons bike tonight, see how much play is in his RD. The more I look at mine, the more this looks like it could be contributing. The play seems excessive.
  • webboo
    webboo Posts: 6,087
    When it is in tension so it goes up from bottom to top on the cassette. If you do several clicks in order for it to go down the cassette, when it doesn’t do this. If you wiggle the cable does it the drop down the cassette.
  • herb71
    herb71 Posts: 253
    If you click the inner lever to drop from larger to smaller, it will move down if you click more than once, but you have to click down 2, and up one to get it to drop down one sprocket, or you get noise, where it is trying, and failing to drop down to 2 cogs.

    Hard to explain, sorry If I am not making things clear.

    The RD does seem to move freely with good spring tension. Just won't index in both directions at the same time. I can adjust to move up, or down smoothly. Just not both.
  • webboo
    webboo Posts: 6,087
    It sounds like it’s dragging on the outer cables
  • herb71
    herb71 Posts: 253
    David, Webboo, I will change the cable outer tomorrow, see if it makes a difference.
  • webboo
    webboo Posts: 6,087
    I had this recently I could get to change perfectly but only one way or the other. Changed the outers and it works fine.
  • masjer
    masjer Posts: 2,613
    As above, changing the outers might improve things. The final loop that enters the RD is particularly susceptible to wear/dirt.
    Another possibility is -have you installed the inner cable on the correct side of the cable clamp bolt on the rear derailleur? This can cause the problem you've described.