hhnngg1

I admit that I'm still confused about the barrel adjusters for my rear derailleur.

Very little seems to happen when I turn the barrel adjuster (near the horns). At least, I can't notice a significant difference in shifting, until the adjuster hits the limit.

I had this bike 'set up' recently, about 6 weeks ago, including cable changes - it was shifting perfectly (triple) until a hammerfest day where I chased some roadies up some big climbs, including sprints, and gradually noticed that the shifting was off a bit. I played with the barrel adjusters some, but after a tiny bit of improvement, I can no longer tell an effect even if I wind it maximally in either direction.

My LBS is happy to re-adjust this for me, but I'd appreciate Any tips before lugging it back to them for this minor adjustment.

GP

I just eyeball it, turn the barrel two turns and see how it works. If it's worse I turn it back two turns and start over. If its better, I fine tune it.

rsacilotto

If you're on the small gear on the back, and you have slack in the cable, you won't notice any difference. There should be a bit of tension on the cable even with the shifter all the way in the high-gear position and the RD on the small cog. Have you tried the adjustment with the RD in a middle gear? You should notice a difference within one turn or less. For fine-tuning, I usually go a quarter-turn at a time. What do you mean by the barrel adjuster "near the horns" - is that the one on the downtube cable stops? If so, have you tried the adjuster directly on the RD? Also, is the cable jamming in the housing? Sometimes if the wrong cable ferrule is used (e.g., one for the brake housing), some of the metal strands in the shift housing can work their way out of the housing and stick through the ferrule, adding friction to the cable.

tagaproject6

Define "a bit off". What are you expecting to accomplish by tweaking the barrel adjusters? Check first to see if there is a lot of play on the cables, then check if the cable end at the RD is properly seated.

Jed19

Barrel adjusters for the rear derailleur are very simple. A quarter turn or slightly less at a time towards where the issue is. In other words, if having problem/hesitation shifting towards the smaller cogs, then turn the adjuster clockwise, if the hesitation is towards big cogs, then turn counter-clockwise.

tanguy frame

check out park tools web site for instructions on settingup the RD.

hhnngg1

Actually, I haven't tried the barrel adjuster adjacent to the RD. That may work better - will give it a try.

Commodus

Well the spring pulls the derailleur to the little cogs. The cable pulls it up the big ones.

Turning the RD barrel adjuster out (counter-clockwise) lengthens the housing, in effect pulling more cable. So if you have lazy shifting up the cassette, you need more pull. This is probably the case here, cuz you may have compressed the housing.

Find out by shifting to small cog. Shift up one at a time. If it doesn't shift, or is sluggish, give it a half turn out. See if it improves. Keep doing this until you can climb up the cassette with no issues.

Now go back down. There should be no hesitation. If there is, you need to turn the adjuster in. Go for quarter turns.

You may find that you can't find a spot where you can go both up and down without problems. If this is the case, you need to have a look at your cables, probably replace them. Very rarely, it's the shifter.

Also, I've been drinking. Apologies for any inaccuracies.

Mtbnomore

If you've hit the point of diminishing returns on the barrel adjusters... Shift into your biggest chainring and smallest cog, then screw the barrels all the way back in (which is actually turning them left, NOT right), then back out a full turn. After that, loosen the cable screw and pull the cable tight again (not so tight to where it messes with your limits, but hand tight), then tighten the screw back up, making sure you're still in the cable groove. If you're still not shifting smooth from there, back the barrel on the derailleur a quarter turn at a time until you're set.

Or, take to your LBS and get the complimentary (at least it should be) post-install cable tightening.

doctor j

If you got new cables 6 weeks ago, they may have stretched a bit and need to be tensioned again.

Inertianinja

Don't just screw around with the barrel adjuster.

Here's what you do:

first, flip the bike over.

(1) shift to the smallest cog.
(2) release the cable.
(3) turn the barrel adjuster so it's all the way in (e.g. minimum tension), then one click out.
(4) using pliers, pull the cable tight (e.g. pre-tension) and then tighten the cable fixing bolt (5-7nm)
(5) shift one cog up. (the chain won't go, don't worry).
(6) add tension to the barrel adjuster until it shifts up to the next cog, then another ~4 clicks.
(7) look closely at where the chain is sitting between the cogs (the bike is flipped over, so you're looking at the bottom of the cassette). it should be sitting so there's equal space between the cog below and the cog above. use the barrel adjuster to add or release tension until it's centered.
(8) shift through the cassette. shifts should be instant, and there should be no rhythmic clicking. check that the chain is centered on each cog.

easy-peasy.

hhnngg1

I'll try this next time. The last time I tried to adjust my cables a la Sheldon Brown & Park tool, once I released the cable, I couldn't resecure it in a position that allowed good shifting and made everything worse. I used pliers, but felt like I might need an even better grip, with a third hard tool or something like that. Was I doing something wrong? (Not going to touch my cables now since LBS just adjusted it for me - they also checked the derailleur hanger.)

Inertianinja

i'm guessing that when you removed the cable, you forgot to reset the barrel adjuster.
even using pliers, there's a limit to how much pre-load tension you can add. the barrel adjuster adds a lot afterwards.

Daytrip

I hate to recommend buying more gear, but a bike stand is invaluable for this kind of adjustment. With a stand, you can play around with it until you understand how it works, and get it dialed in just right. Because everything is bass ackwards (clockwise turns loosen, rather than tighten the cable), it takes some concentration and trial and error to learn. JMO. BTW, I always use the adjuster on the der when using a stand.

Bear in mind that a "perfect" adjustment on a stand may not be as good under actual battlefield conditions, since you're putting more pressure on the drivetrain when you ride, and it will behave a bit differently. That's what the front barrel adjuster is for--making minor adjustments on the fly.

hao

It really isn't that complicated.

With no cable tension, derailleur goes to the most relaxed position. For the rear, it's the hardest gear.
Adding cable tension allows you to go up the cassette. The cable is "pulling" the derailleur up.

What does this mean? When there's not enough cable tension, the derailleur refuses to move up. So you need to increase tension.

How do you increase tension? Well, for small adjustment, use the barrel adjuster. For large adjustment, loosen the nut and tighten the cable.

nhluhr

Don't flip your bike over unless you want scuffed saddle and handlebars/brifters.

If you DO have to loosen the fastening bolt on the cable, make sure to do it in the smallest cog/chainring. This is where you won't have any tension on the cable and it will be easy to re-fasten it. It is uncommon to need to re-fasten a cable in a tighter position if it was indeed set up correctly. So-called "cable stretch" (actually just seating/wearing of the various housing/cable ends) is minor and can almost always be compensated by the adjuster barrel. You should be very certain something else isn't wrong before you do this.

Inertianinja

oh come on. he can put a towel down if he's really worried about that.
having the bike upside down is the easiest way to eyeball the chain's alignment on the bottom of the cassette.