How to tune a rear derailleur

Tuning derailleurs have always intimidated me. Everytime that I mess with them, I make it worse. So I turned to RL, our resident master wrench, for some advice.

Here’s the basic procedure with illustrations. We used the Ibex Trophy with a Shimano Deore LX derailleur. Your bike maybe different but the same principle applies.

First, make sure that the tension on the cable is adequate. It should feel tight like a guitar string. If it’s there’s too much play, then tighten the cable.

Try shifting again. If you’re still having shifting problems, keep reading.

tuning a derailleur

Second step is to shift the chain on the front middle ring:
tuning a derailleur

Third step is to have the chain on the smallest cog:
tuning a derailleur

and then shift to the next cog up:
tuning a derailleur

Now turn the adjusting barrel all the way to the right:
tuning a derailleur

Start cranking the wheel and turn the adjusting barrel to the left while counting the turns until the chain jumps to the next cog.

tuning a derailleur

Once the chain has jumped to to the next cog, shift all the way down to the smallest cog. Turn the adjusting barrel all the way to the right.

Then turn the adjusting barrel 1/2 the number of turns, counter clock wise, you counted (for example, if it took 4 turns for the chain to jump to the next cog, then you turn it 2 turns).

tuning a derailleur

You should now be able to shift gears without hesitation. If you see that there’s a little hesitation, adjust the barrel slightly, taking half turns counter clock wise until you are satisfied with the shifting.

Hope that helps, we just saved you $20-$30!

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0 thoughts on “How to tune a rear derailleur”

  1. This is a great post Moe! When RL first showed me how to do this, I was amazed on how easy it was. And youre right, $20 – $30 saved each time you do this.

  2. HH says:

    Other things that might affect your ability to tune so you might want to check:

    * Any bent tooth on the cogs

    * Worn cogs – may need a full drive chain replacement depending on severity.

    * Bent derailleur hanger, especially after a crash. Many bikes now have replaceable derailleur hangers, especially if they are made with aluminum.

    * Bent derailleur cage, especially after a crash. Unfortunately, you’ll probably need to replace the derailleur.

    These problems are more troublesome to fix, so visiting a bike shop maybe the best course of action.

  3. Mike says:

    totally different technique to what i usually use, but i t is a damn site quicker! i wil give it a go tonight! THANKS

  4. Steve says:

    A terrific presentation. I have a bike repair book that also shows how to do this but your photos and explanation really simplify the process.

  5. bif says:

    I broke my bike in half but the real derailleur tuned like a champ. Hurts to ride it, though. Hurts to ride a bike that’s broken in two pieces. Like riding an electric floor sander or perhaps a puma.

  6. lp says:

    derailleur images for adjustment page are not showing.

  7. courty says:

    this sounds pretty straight forward, which is great, however I’m having some trouble with one important element: my barrel adjuster won’t turn. the one for my front derailleur will turn if given enough slack in the cable, but the one for the rear refuses to budge. Any suggestions?

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