am0n

Tried to search for this, but haven't been able to really get an answer, so turning to y'all.

On my bike, I have three different types of barrel adjusters. Two on the downtube, two on the brakes and one on the rear derailleur (actually two more on the interrupter brakes). All three are different. The RD and brakes look similar (black shrouds, the shroud has nubs at each quarter) but the brakes are larger and have a metal shroud that extends. The downtube adjusters are the smallest and don't look like the others (smaller, appear to have more nubs, still a black shroud).

What are the differences? All appear threaded into whatever they are attached to. Are the threads all the same size/count? Do they accept the same size outer? Are they universally replaceable? Or are there differences between each location?

I have a friend whose brakes have a different adjuster as well. Silver, smooth, with what looks like a lock nut. Can this be replaced by one of the black shroud ones? What would I need to look for if I wanted to replace it?

I've looked at, say, Jagwires website, but they don't seem to have the same looking ones, so I am trying to understand what would be a replacement and what I'd need to be mindful of if trying to replace them.

woodcraft

Brake cable & housings are larger than shifter cable & housings, so the adjusters are also different size.
I doubt that various ones with threads are interchangeable, and finding bit X to fit bit Y would be difficult.

am0n

Thanks. I am aware the cables are different, so I guess thinking a bit more it makes sense they may be different (although I wonder if the ferrule on the shift cable works result in the mating end being the same).

That said, how about the overarching question? What do I look for in the event I needed to replace one? How do I know if one is designed for brakes vs shifting? How can I confirm it'll fit in whatever I need it to fit on as a replacement?

Iride01 

Why do you want to replace it? Don't like the color? Don't mix and match adjuster pieces parts. Especially in-line adjusters. They are inexpensive enough, just order the complete new adjuster.

You might mix and match barrel adjusters. But why if the current ones are working.

Troul 

why do you have them now? If the system is set up correctly & maintained as it should be, then the aftermarket adjusters wouldn't need to be installed. I personally experienced it to be more hassle & work to have them, & when installing them, you're typically a few steps away from doing the work properly by replacing the junk cable/housing.

am0n

Assume one is broken and I need to get a replacement that fits into my RD, brake calipers, or frame.

Troul 

instead of dealing with another mistake, replace the entire length of cable with housing & set the tension. You'll be better off.

Geepig

It depends on several factors, and it is an interesting question.

Some of my brake levers have barrel adjusters while others do not, and the ones without use a cable with an extra loose cover on the housing end to fit into the brake lever mount.

All the barrels on my side pull calliper brakes seem to be interchangeable, at least the ones I have tried, and they are metric. Sometimes the adjuster suffers damage due to whacking into something, poor quality manufacture or corrosion.

Take the cable out, remove the barrel adjuster off and trying a known size nut on the adjuster or a bolt in the hole is a good first step.

andrewclaus

Shift cable adjusters with the movable plastic sleeve are self-locking. There's also a spring under the sleeve to engage the lock.

Brake adjusters have a lock nut. The brakes are life safety items and all components are larger and stronger--no plastic.