Explain Barrel Adjusters

[Onno]

This is probably a stupid question, but could someone please explain to me how those dumb adjusters work. I'm talking about the plastic ones that you turn and a small metal ferrule (or something) slowly slides in or out, effectively shortening or lengthening the cable housing. The latest set came with some replacement Deore shifters for my commuting bike. My issue is that in my experience with these things over the years, it seems that you can turn and turn it, and nothing seems to happen. The metal sleeve (or whatever it is) inside the barrel doesn't move one way or the other. Or it moves a bit and then stops even though I can still turn the barrel.

[idrinkwater]

Maybe it's at its limit? Detach the cable and see if it moves without the tension of the cable. If not, the metal "ferrule" may not be threaded in properly or at all. If it does move without cable tension, figure out how many turns it takes to get to the "middle" and re-bolt the cable.

[Kobe]

On some adjusters you need to pull up and turn on the plastic part in order for the plastic tab on the underside to disengage from the ferule.

[carpediemracing]

This is probably a stupid question, but could someone please explain to me how those dumb adjusters work. I'm talking about the plastic ones that you turn and a small metal ferrule (or something) slowly slides in or out, effectively shortening or lengthening the cable housing. The latest set came with some replacement Deore shifters for my commuting bike. My issue is that in my experience with these things over the years, it seems that you can turn and turn it, and nothing seems to happen. The metal sleeve (or whatever it is) inside the barrel doesn't move one way or the other. Or it moves a bit and then stops even though I can still turn the barrel.

If you turn it and nothing happens then you've probably unscrewed the metal piece from the boss all the way. Basically cable tension is holding the adjuster barrel in place.

If you try to turn it and it doesn't turn you've probably tightened it into the boss such that the metal ferrule is bottomed out.

There are variations.

If you unscrewed the metal ferrule all the way and didn't carefully thread it back in, you may cross thread it when you finally screw it back in. if that's the case you may be able to turn the barrel adjuster a turn or two but then the ferrule really digs into the boss and it stops moving.

The ferrule can break in two so the plastic barrel isn't moving the part that's in the boss.

For best practice what I do is tighten the barrel adjuster in all the way (metal ferrule is bottomed out). In order to isolate the ferrule threads I pull the plastic barrel up against the spring so the metal ferrule is exposed. Then I screw in the metal ferrule. It's very clear if I'm threading it properly or crossthreading it. Then unscrew just a touch, maybe quarter turn. Then I put tension on the cable and adjust as necessary. If the cable gets loose then I make sure it's not because of housing failure or something weird like that. Then I'll bottom out the barrel adjusters, minus quarter turn, and retension the cable. Then adjust as necessary.

[eddief]

Put derailleurs in small on front and rear, releases tension, adjuster easy to turn that way. If they are not tightening or loosening cable tension, then you do have faulty adjusters.

[thwart]

Bear with me here... Campy's approach is superior.

Avoid overboard engineering.

Or if you prefer... K.I.S.S.

;)

[Ralph]

After you get your derailleur stops set...front and rear....taking the slack out of the cables and housing is how to make your bike shift correctly. Barrell adjusters make fine tuning easier.

[suissecheese]

On some adjusters you need to pull up and turn on the plastic part in order for the plastic tab on the underside to disengage from the ferule.

Woah! have an old mountain bike I sometimes use and just realized this is why i can never adjust things on it. Feel dumb, but also happy

[Dead Man]

I ditched those things years ago.

Some say you need 'em for front ders (the rear has one already), but I haven't needed one for a grip. Stretch the cable, take up all the slack, cinch down.... should be good.

[tbike4]

Barrell adjusters make fine tuning easier.

^This. I just installed a FD-6800 on a friends bike and a FD-9000 on my bike and used an inline barrel adjuster. It makes it so easy to tweak the FD to the just the right position so you have all 4 clicks in there. I don't think I could get enough tension on the cable with FD 5800, 6800, 9000 with out the cable stop adjuster or inline. My 1.5¢ worth.

[dgauthier]

I always thought the point of barrel adjusters was to allow for tweaking the shifting while riding.

Proper use would entail screwing them all the way down (ie: as short as possible) when installing new shift cables the first time. Then, as the cables stretched over time (or as the housing compressed, or whatever the popular wisdom is about the process) one could unscrew the adjuster and lengthen the housing as needed on the fly while riding.

Over the life of the cables, if the adjusters ever got unscrewed all the way, the proper thing to do would be to screw them all the way back down and retension the slack cable at the derailleur. Repeat tweaking the barrel adjusters from time to time as required.

So a happy adjuster is one that's screwed almost all the way down. As others have mentioned, maybe yours are unscrewed all the way. If yours are broken and can't be screwed back down, hey, get new adjusters.