Gonemad

Recently I had a new shifting cables installed, and used the barrel adjuster on the STI brifter to tune the shifting for the front derailleur (as one normally would). The only problem is during a ride, that barrel adjuster loosens up on its own, and then so much for that fine tuning (read: crappy shifting). Other than this problem, everything else is great. I am thinking of using some thread compound on that barrel adjuster to keep it from coming loose. Obviously, nothing that would freeze it up. Any thoughts or pitfalls on doing this? BTW, this is a 12 year old Klein road bike with a triple crank and 9 speed brifters. For about 9 of those years that bike was not ridden do to a neck injury. Thanks for reading

HillRider

I don't know of any road STI brifters with a built in barrel adjuster so is it mounted on the frame or in-line in the cable housing?

Frame mounted barrel adjusters typically have a spring to hold tension on the rotating barrel and ratchet teeth on it to prevent turning spontaneously. In-line adjusters either have a jam-nut or tight threads. Check your adjuster for missing parts.

Rowan

First of all, make sure when you are adjusting the barrel, that the cable outer on either side of it isn't turning or twisting as well. If the end hasn't been cut cleanly or trimmed, it can snag in the base of the barrel, and in short time it returns the adjustment back to or close to where you started.

Over quite a few years of travelling by air and on the road with bicycles, I've noticed that downtube barrel adjuster, complete with springs, somehow can loosen. A tiny dab of Loctite 242 is one solution to the loosening issue.

Also, if the cabling is new, did you instal it yourself, or someone else? And were the old outers used? Generally you need to pull hard on the levers several times after installation to ensure the inner cable finds the shortest route to the derailleurs, or bed in. Then readjust the barrels to get the right shifting. This is even moreso essential if the old outer sheath is retained because the old inner cable has worn a path through it.

Gonemad

Turns out my brifter description is missing key details. These 9 speed 105 STI's brifters have the shift cables coming out of the side of the unit, and at the point were it exits there is installed an in-line barrel adjuster (it is not shimano branded..my bad) between the end of the cable housing and the brifter. The adjuster has plastic teeth that should prevent it from loosening, but over the years those teeth seem to have lost their effectiveness. Shifting and vibration seem to be working it loose (takes about 20 minutes of ride time), so I'll try some thread compound as I was thinking and as recommended. If that fails I will replace the barrel adjuster (now that I've figured out I can). Thanks for the feedback.

joejack951

The only time I have experienced this (which I mistakenly blamed on the teeth not engaging enough at first) was when I had a cable ferrule bind in the adjuster from corrosion and/or accumulated grit. This caused the housing to wind up when the barrel adjuster turned and then, in time, about 20 miles, the housing would twist itself back to its starting point. I'm not sure why it took me several rides to get fed up enough to re-cable the bike but it did. When I removed that bit of housing I found the ferrule firmly stuck in the adjuster which made the real source of the issue very apparent. Needless to say the bike was fine after installing new cables, housing, and ferrules plus cleaning out the adjuster.