mara777

I've tried to research how to remedy this issue, but haven't been able to figure it out.

The barrel adjuster for my FD is very difficult to turn. The black piece (I don't know the name, but it's shown in the photo) turns WITH the adjuster. I have to hold or clamp the black piece to get the adjuster to turn. If I keep moving the adjuster, it loosens up a little (until next time), but still does not turn easily.

Kontact 

You can try putting a drop of oil in the mechanism, a tiny bit of glue where the cable housing goes in to give the ends traction, or just replace it with one that works right.

soyabean

This is one of those times it is safe to use household WD40.

Just needs a little lube and love

Iride01 

Till you replace it or fix it, you can try putting the chain on the big ring then activating the shifter to go to the small ring without moving the cranks. That'll relieve some of the tension on the inner cable that might be helping to make it hard to turn. A ¼ turn can be a lot.

You can also just loosen the pinch bolt and reposition the cable. But that is some trial and error in placement that can be tedious. And maybe even break a strand in the cable and start it fraying if you are one that tightens the pinch bolt like it's holding the rotor blades on your helicopter.

Andrew R Stewart 

The photo looks to show the adjuster being nearly, or completely, run out. If this was on a shop repair I would try to loosen the cable at the anchor bolt, run the adjuster down to its minimum and resecure the cable as I tugged it taught. I also apply a small dab of grease on the adjuster threads. Andy

maddog34

those things REQUIRE drag or they will readjust themselves... and it's time to readjust the cable instead of that inline adjuster.

Kontact 

The mechanism drag should be less than the drag on the housing ferrule so you can turn them with one hand.

tFUnK

Are you using adjusters meant for brakes for the derailleurs? There's a 1mm difference in diameter. You may try putting a layer of tape around the ferrule before seating the ferrule into the adjuster and see if that provides enough friction.

maddog34

and all machined parts should be perfect.... hint: nothing is perfect.

did you consider trying to do your "one handed adjustment" with the cable loaded by a derailleur spring's return force?

heck, i'd love to see a vid of this "one hand adjustment" with or without that loading......

Kontact 

Why not just try it yourself next time you're in a bike shop? I've worked on hundreds of these and they function as I stated.

maddog34

i'm in a "bike shop" right now. post that vid soon, ok? make sure it's a similarly short inline adjuster.

Andrew R Stewart 

In the casing outer diameter but not the ferule's diameter. Both brake and gear casing ferules are about the same outer diameter at about 5.8mm. The brake ferule will have a thin wall and is usually made of metal. The gear one is usually plastic with a thicker wall. Andy

Kontact 

No one cares about your demands. I was a service manager for years, and you dont know what you're talking about.

The black end grips the ferrule by design. End of story.

And that isnt a very short adjuster. Many are 50% shorter than that.

Kontact 

tFUnK

I have not measured the ferrules but I do know that my standard brake ferrules seat nicely inside my brake cable adjusters, whereas if I put a shifter ferrule in the same barrel adjuster, there is some slight play. Meanwhile, if I tried to put a brake ferrule into a shifter slot on my brifters, it gets stuck, but the plastic shifter ferrule seats nicely but does not get stuck 🤷‍♂️

tFUnK

To be fair I've had inline adjuster that were easy to adjust with one hand, and others that required the other hand to hold the non-rotating end in place. Whether this discrepancy is a product of design intent or matter of wear over time, I can't say.

maddog34

you care...

Kontact 

No one makes a barrel adjuster where you are supposed to hang on to a piece that disappears entirely into the body of the adjuster. The ones that take two hands aren't working right.

The side that recesses has something in it that is supposed to grip the housing ferrule - usually something rubbery. If that recessed part is turning, it is either because the mechanism friction is too great or the ferrule traction too low due to grime or wear. If the mechanism is bottomed out and you keep turning it, that will damage the rubber gripper over time.

There are also barrel adjusters designed to into cable stops or shifter bodies. Same principle - you can see the rubbery grommet on the narrow end that keep them from rotating: