Bicycle Shifter Adjustment Barrels

firebus's picture

Most bikes have adjustment barrels for the shifters right next to the shifters themselves. If you're riding along and you notice that one of the derailers is a little off, you should be able to twist the adjustment barrel a little bit to bring the derailer back in line.

I can never remember which way to turn the barrel to fix which kind of problem, and every now and then I spend some time to figure it out but because bicycle shifters are a wonderland of handednesses I can't ever remember, hence this article.

Rings and Sprockets

The first set of asymmetry is in the rings and the sprockets. If you look at the rings, you'll see that the small ring is closest to the inside of the bike. However, the sprockets have the big sprocket closest to the inside.

However, because the small ring in front is the low gear, and the big sprocket in back is the easy gear, in both cases the easy gear is on the inside.

Shifters work by tightening and loosening a cable that leads from the shifter to the derailer. The cable gets tighter to move to a bigger ring or sprocket. The cable gets looser to move to a smaller ring or sprocket.

Because the small ring is closer to the inside in front, and the big sprocket is closest to the inside in back, the cable gets looser to move the chain towards the inside in front, and looser to move the chain towards the inside in back.

Confused yet? Basically, there are two groups of attributes for the rings and sprockets - those that stay on the same side both front and back, and those that switch sides between front and back:

Same-side attributes

  • Inside/Outside (by definition)
  • Easy or Low gear, Hard or high gear

Switch-side attributes

  • Small ring or sprocket/Big ring or sprocket
  • Tight cable/Loose cable

Here are some diagrams:

Front RingsFront Rings

Rear SprocketsRear Sprockets

Shifter Adjustment Barrels

The left shifter controls the derailer for the front rings. The right shifter controls the derailer for the rear sprockets.

Following the universal principle of "Righty-Tighty, Lefty-Loosey", the barrels loosen the cable when turned clockwise, and tighten the cable when turned counter-clockwise.

But another way to think about turning the barrels is "away" from the rider, and "towards" the rider. Since the barrels usually mirror each other, one barrel will turn clockwise when turned away from the rider, the other will turn counter-clockwise when turned away from the rider.

Different bikes have adjustment barrels with different orientations. The bike in question here has a cable that enters the shifter from the inside of the bike, with a barrel between the cable and the shifter.

And, I'm going to consider clockwise and counter-clockwise from the perspective of someone looking down the cable at the shifter. YMMV.

Given these assumptions, clockwise for the left shifter barrel is "away", and clockwise for the right shifter is "towards". However, due to the asymmetry of the rings and sprockets, on both shifters turning the barrel away from the rider will move the chain to the inside, and turning the barrel towards the rider, will move the chain to the outside of the bike.

  • Clockwise loosens the cable
  • Counter-clockwise tightens the cable
  • Away moves the chain inside
  • Towards moves the chain outside

And some diagrams:

Left ShifterLeft Shifter

Right ShifterRight Shifter

Is This Useful?

The goal is to be able to have something easy to remember so that when your chain is slipping between gears, you can fix it while riding.

It depends on how you perceive the problem with the chain. If you can tell that the chain is lagging when you try to put it in an easier gear, then you want to move the chain more inside (since inside is always easier), which means turning the barrel away from you. And vice-versa.

If you can tell that the chain is lagging when you try to tighten the cable, then you want to make the cable a little tighter, so you should turn the barrel counter-clockwise. And vice-versa.


Comments

i'm dumb. where do the bread

i'm dumb. where do the bread and drink go...?


firebus's picture

okay, so you want a mnemonic then?

how about:

if it's hard to make it easy, twist the barrel down the streetsy
if it's hard to make it hard, twist the barrel in your nards


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