Not shifting into 2nd smallest cog??

thebigman
thebigman Posts: 58
in Workshop
Hi folks. I've got a gravel bike with grx shifters and ultegra mechs, and I can't get it to shift onto the 2nd smallest cog as well as the others.
I've changed cable, checked hanger was straight, even used another cog from another cassette which I know was fine, but problem still persists.. changes fine all the way from the top until I get to the 2nd smallest and won't seem to pop down. Click it again and it'll go to the bottom..

Comments

  • MidlandsGrimpeur2
    MidlandsGrimpeur2 Posts: 2,123
    Do you use that cog a lot and is the chain worn? Sometimes I get shifting issues on heavily used cogs when the chain is worn, it will shift into all other gears perfectly but skip on the well worn cog.

    If not, and you have changed cables and checked RD alignment, as you say, it is usually an indexing issue. I have had it where everything is fine bar one or two cogs and it just takes a bit of fettling and fine tuning with the barrel adjuster to get everything perfect. The overshifting onto the next cog is usually a sign of this IME.
  • PMark
    PMark Posts: 160
    Could also be the angle the cable is going into the RD (if this is a long term issue with bike) I have heard of others with similar issues with shimano 11 speed. Have a look for some guides for your bike/rear derailleur to make sure it is done correctly.
  • MattFalle
    MattFalle Posts: 11,644
    all ok on the lkmit screw adj?

    sometimes a 1/4 turn here or there solves it for no understandeable reason at all.
    .
    The camera down the willy isn't anything like as bad as it sounds.
  • trevor.hall12
    trevor.hall12 Posts: 493
    edited September 2022
    Sounds like a limit screw
    Disconnect the cable and see if the RD goes down the range far enough if it it dosnt its the limit screw if it does its a cable / shifter issue
    Is it an 8000 RD as the cable route on it is essential ,seen a few bikes with people routing it the wrong side of the screw
  • Munsford0
    Munsford0 Posts: 680
    If it drops into the smallest sprocket on the next click it can't be the limit screw that's to blame. Fiddling with the barrel adjuster might do it.

    Isn't the latest DA / Ultegra / 105 meant to have the extra flexible outer cable at the RD? Has yours got this? If it's bog standard SP41 it could be too stiff

    https://www.totalcycling.com/en/Shimano-OT-RS900-Rear-Derailleur-Outer-Cable-Housing-240mm/m-24466.aspx
  • pblakeney
    pblakeney Posts: 27,416
    As it drops to the smallest sprocket I'd be looking at the cable as the likely culprit.
    The above may be fact, or fiction, I may be serious, I may be jesting.
    I am not sure. You have no chance.
    Veronese68 wrote:
    PB is the most sensible person on here.
  • trevor.hall12
    trevor.hall12 Posts: 493
    If its going though the range of gears then it's a cable or shifter issue
    Do you have a pic of the outer to the RD ,might be a bit short
    As you've changed the cable it would suggest the outer having something in it ,though that would be strange it happening in the same cog every time .
    Have you tried spraying some wd40 into the shifter too ?
    As its happening in the same cog consistently it suggests its possibly sticking in the shifter more so than the outer casing as it would more likely be random
  • thebigman
    thebigman Posts: 58
    Thanks for replies. New cassette, new chain and new shifters. Munsford0 you may have nailed it, I'm using standard gear cable.. I'll get one of the more flexible cables ordered and try that..

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