Viewing 23 posts - 1 through 23 (of 23 total)
  • Arrrghh – I can’t shift down from the largest cassette cog?!
  • holdenc
    Member

    Hello!

    I have this persistent enigmatic problem that has defeated two bike shops and me! I would be highly grateful for any input.

    My rear derailleur (SRAM Rival 11) will happily shift into the lowest gear (largest cog), but it won’t shift to the next largest one unless I shift two or three gears up.

    Visually it just looks like the derailleur isn’t being given enough slack when I shift up from the lowest gear.

    I have replaced the inner, the outer, and removed all internal cable guide sleeves in a bid to minimise cable friction, but this theory doesn’t really make sense because the derailleur tension should be highest in the lowest gear anyway and it shifts into the highest gear no problem.

    I’ve taken the casing off the shifter to check that the cable is being pulled when it shifts down and indeed it is.

    The limit screw is certainly adjusted properly, and if I move the limit any more outboard I can’t shift into the largest cog.

    Mech hanger and derailleur look fine.

    The bike is 1 a 2019 Giant TCX (not that I think this might be relevant!).

    Any wild suggestions welcomed, this is driving me nuts!!!

    Premier Icon Tiboy
    Subscriber

    Tension screw? Had a derailleur get hooked on the cog if it’s too close

    Premier Icon matt_outandabout
    Subscriber

    Bent mech hanger or deraileur?
    SRAM mechs can also have a ‘feature’ slackness to the top pivot – grab the mech and wobble it… That slack can be enough to not shift properly.

    bigyan
    Member

    B limit set correctly? Hanger alignment ok? Chain length ok?

    It does seem to be a feature of recent Sram rear mechs. Quite a lot of warranty issues.

    If you completely remove the cable and shift the mech by hand does it stick?

    If the mech spring over centres you can sometimes “fix” it by putting a washer between the mech and hanger

    montgomery
    Member

    If it was a Shimano mech I’d suggest switching off the clutch as a diagnostic, but not sure you can do that with SRAM. Dry clutch can cause that symptom, though.

    Premier Icon scotroutes
    Subscriber

    Mech hanger and derailleur look fine.

    You’ve had it in two bike shops and neither have checked the hanger?

    Premier Icon simondbarnes
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    IME you can cure it temporarily by fitting a new sram mech or permanently by fitting a shimano drivetrain.

    submarined
    Member

    I had a similar problem on an X01 much. Took a link out, adjusted the b screw, no more issues.

    pdw
    Member

    I’d start by running a fresh, full length outer straight from the shifter to the mech (i.e. don’t try to run it through the frame or along the handlebars) and see if that fixes it.

    I’ve had a couple of bikes where the internal routing of the “exposed” bits of inner have caused problems, either due to the sharp angle where they go into the down/top tube, or at the bottom bracket. A bit of drilling and switch to full length outer have completely fixed it.

    A third bike (with SRAM) has had the full length outer treatment which improved things, but it was still very sensitive until I switched rear mechs (Force 22 to Rival 11). The cable routing on the SRAM hydro levers is inexplicably crap, and taping the outer to the bars creates a tight bend and lots of friction. The up-shifting problems I had were at the other end of the cassette (smallest cogs).

    SRAM inners are nominally slightly smaller than Shimano ones, so might be worth checking that you’re using a SRAM inner, although switching to SRAM inners was one of the many things that didn’t fix my problem 🙂

    holdenc
    Member

    Okay, thanks for all the suggestions.

    Will take a look at chain length, B screw and another close look at the hanger tomorrow.
    Fingers crossed!

    velocipede
    Member

    B screw adjustment will solve it…….

    ……probably

    Premier Icon Poopscoop
    Subscriber

    Bike ships should really have checked B screw etc. Odd if they didn’t.

    Waderider
    Member

    Sticky cables normally affect sprockets closest to the dropout.

    Check b-tension screw adjustment, alignment, and ability of mech to cope with the tooth count on the big sprocket.

    Premier Icon martymac
    Subscriber

    B screw is quite a likely culprit.
    You won’t be able to tell visually if the hanger is bent, (well, not unless it’s massively bent anyway) a hanger alignment tool is definitely required for that.

    holdenc
    Member

    Thank you for all the help!

    Adjusted b-tension. I got it working shortly by winding out the b-screw so far that the derailleur was nearly touching the cassette, but couldn’t find a consistently working solution. It’s like the derailleur is moving a variable amount which each up/down. Weird, cause it’s only 1 year old.

    I’ve ordered a new mech hanger so that’ll be the next thing, and then a new derailleur if still no luck.

    Premier Icon 40mpg
    Subscriber

    I had similar, new jockey wheels sorted it. Play in the old ones combined with sram wonkyness and a fairly tired chain combined was sufficient to cause the issue.

    Premier Icon matt_outandabout
    Subscriber

    It is SRAM. They come with enough play on the top pivot and jockeys to create that issue.
    Warranty it.
    Buy Shimano.

    Premier Icon welshfarmer
    Subscriber

    I have the same issue with a nearly new Shimano XT 11 speed so it is not exclusive to Sram. What did help (though hasn’t completely cured it) was a chain degrease. Although pretty clean it had a fair build up of wax (Squirt) which seemed to be hindering the lateral movement of the chain. A good soak in degreaser, wash and dry and a fresh coat of lube and it worked much better. I still think it is a slight compression in the cable outer where one of the frame clips was done up a bit tight, though pulling the cable back and forth seems to have no resistance.

    Premier Icon neil the wheel
    Subscriber

    I have solved similar issues in Shimano mechs by replacing the jockeys with non-floating ones. Makes them shift like Campagnolo!

    Premier Icon survivor
    Subscriber

    What a coincidence.

    Have a bike at work with exactly this problem. Sticks in 1st and won’t drop to higher gears as described.

    play on pivot and a bit on the jockey wheels, mech hanger is fine

    Was doing my nut in so was gonna ring customer tomorrow to recommend new mech.

    We don’t see much SRAM stuff but every time we do is usually a ball ache!

    holdenc
    Member

    Replaced the mech hanger (it looked fine, but needed a spare anyway!), and no change.

    I’m going to replace the derailleur and will report back.

    pacerc100
    Member

    Check the cable is routed correctly at the mech end. From memory it goes about half way round the black quadrant and then through the hole and bolts up. I had one set all the way round the quadrant and it displayed these very symptoms.

    holdenc
    Member

    I’ve sorted it!

    It was a second-hand bike I bought recently and it turns out the chain was a couple of links too short. Apparently SRAM 11spd needs 2 spare inches of chain not 1. Swapped the chain over and it’s shifting down nicely now!

    Thanks all for your help.

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