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My inline front mech barrel adjuster unscrews itself while riding. It's on the down tube so I can tweak it on the move, but when I realise it's moved isn't always an ideal time. For example I shift from the big ring to the middle ring, nothing happens, but I know that clicking the lever again will put me in the granny ring. In gloves I can only adjust it in the granny ring anyway as that's when the tension is least.

It has a spring but that doesn't seem to help; in fact it may make things worse. I've tried loctite (a not-too-hard variety I got as a sample from a loctite rep years ago, but effective on other things). It doesn't seem to help, but that may partly be because the braze-on is likely to have grease in it despite my best efforts. Ideally I'd fit a locking nut but there's very little space, it would have to be knurled, and the thread doesn't look like a normal one.

Barrel adjuster - see the freehand circled part

Yes, it's filthy, but that's mostly from yesterday's 200km ride.

So how can I lock off this adjuster (until I need it of course)?

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    Pics to follow. It's been slightly bugging me for a while but I was prompted to actually ask by Why are barrel adjusters different for brakes and gears?
    – Chris H
    Apr 8 '19 at 20:01
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    You might try some "adjustable" Loctite. It can be a little hard to find, but I know it saved me once, years back, when I was having trouble with the adjustments on my ski bindings. Apr 8 '19 at 21:17
  • @DanielRHicks according to the loctite rep a few years back their threadlocker is all adjustable to some extent (loctite also make retaining compounds that definitely aren't). The one I've got gives quite a tight hold when properly cured, but the residual friction after that hold is broken isn't all that much. But in this case it seemed to do nothing at all.
    – Chris H
    Apr 8 '19 at 21:23
  • No product rec - but I found this "vibra-tite.com/threadlockers/removable-reusable-threadlockers/…"
    – mattnz
    Apr 8 '19 at 23:04
  • @mattnz that's interesting. While they make no claims as to grease tolerance their approach should be inherently better at handling greasy threads on the female thread than a traditional bonding threadlocker
    – Chris H
    Apr 9 '19 at 5:45
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One option is to tighten the existing adjuster completely, turning it into a stop. Then fit an in-line barrel adjuster which will sit in a length of outer (ie, not against a stop)

enter image description here enter image description here

Some 2 pot epoxy mixed, or a metallic paste like JB Weld would make short work of the existing adjuster moving.


Option 2 might be to replace the adjuster completely. New ones are relatively cheap and look something like this:

enter image description here

Just be sure to get gear adjusters, not brake adjusters because they're based on a different diameter of the outer cable, and a gear cable will be sloppy in a brake adjuster.

You'll want to chase the threads in the frame stop with the correct sized tap too. If there's not a lot of metal material left in the frame, then it may come down to replacing the cable stop, or finding some way to use a small nut and bolt the adjuster on through the now less-threadded hole.


Option 3 - swap out that cable stop for a loop, and run a single length of gear outer housing from shifter down the down-tube to the front mech. May need to resort to cable ties to hold the outer to the bike. Depends if you have a way to stop the cable further down. There's a Problem Solver's stop that may help, but this would need the in-line adjuster already mentioned too.

enter image description here

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    Maybe next time I'm changing the inner cable I'll remove the spring, bottom out the existing adjuster, and fit an inline one. I've just changed it though so it might be a while. The frame and all braze-ons are steel and the adjuster is brass so the female threads should be good, but I have a funny feeling it's not a standard thread
    – Chris H
    Apr 9 '19 at 12:48
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The thread on that looks pretty worn in the photo, so I'd give up on that barrel adjuster entirely. The thread on the frame is probably simlar, so replacing it with another like it might not be worthwhile.

Your other option is a new inline barrel adjuster like this one further up the cable. To fit it, you need to unhook the cable from the derailleur, to get the outer cable section between the shifter and current barrel adjuster off the inner cable. You then need to cut the outer into two pieces. When reinstalling the outer, slide one piece on, followed by the barrel adjuster, then the other piece. The rest is the same as before, only now you can leave the old adjuster wound right in so that it can't slip any further. Gear adjustments will be done through the new inline adjuster.

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  • You can't see the thread. That's the spring that's supposed to apply a force against vibration. The thread looks brass like the knurled part
    – Chris H
    Apr 8 '19 at 21:19
  • ... But your conclusion might be the right one anyway. The rear adjuster doesn't move by itself, but has had at least as much tweaking, as I've got through a few rear derailleur cables.
    – Chris H
    Apr 8 '19 at 21:25
  • If you have a rear adjuster, could you loctite that one in place and just use the rear?
    – mattnz
    Apr 8 '19 at 23:03
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    If you wind the existing one right in, then the loctite won't even be necessary. It will wind itself in under load, but won't wind back out once it's screwed all the way in. Apr 8 '19 at 23:15
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    @ChrisH oh yes sorry, delay. I was thinking that if you were to have two adjusters for the rear and none for the front, that could be a way to have one adjuster for each. If there’s no adjuster on the rear mech then it falls over.
    – Swifty
    May 12 '19 at 9:53
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I have the same issue, and I also have a Genesis Croix De Fer with these brass adjusters. Apparently when the cable moves from just turning the handlebars - the adjusters also move around - it really seems like a design flaw, albeit I've known CdF users that don't have this problem for some reason. So, any time you screw them out for your desired tension, they eventually just turn back in and ruin the shifting. My front/left one always behaved like this, I bought the bike used. As for the right one, I just use the adjuster on the derailleur itself. Interestingly, the left (bad) one moves much deeper into the frame than the right one and is a bit loose, especially the more it is moved outwards. Maybe the threading really IS bad, as some other commenters noted.

Some things that can be done:

Replacing the adjusters with something similar - I'm pretty sure the threading is an M5.

Dropping some Loctite Blue or similar on the threads and selecting the desired tension.

Adding an inline barrel adjuster - that's what I did, and it mostly eliminated the problem. It makes the cockpit a little less clean though. I'm currently in progress of replacing the flawed brass adjusters with something else that won't slip as much.

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    I wonder if having a longer run of outer from the stop up to the bars might help? More length to absorb the bar's rotation.
    – Criggie
    Oct 6 '20 at 21:58
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    Probably. My housings were pretty long to begin with, though. Either way I've got a set of pretty fancy looking M5 adjusters on the way. When they arrive I'll test them and see whether or not they're any better than the default brass ones.
    – Cheremenin
    Oct 6 '20 at 22:22
  • I've considerably shortened my cable runs, and early indications are good. The more direct run seems to get less twist in it
    – Chris H
    Oct 22 '20 at 12:42

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