Know How

How to Correctly Adjust the Rear Derailleur on Your E-mountainbike

18.11.2016
by


Once the chain throws its toys out the pram, jumping from cog to cog and making a racket as you’re pedalling, then it’s probably time to adjust the mechanism. Here’s our guide on how to put these tantrums to bed.

Difficulty

Medium

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Required tools

  • 2.5 mm allen key
  • 5 mm allen key
  • possibly a 25 mm Torx drive

How to

This is a complete how-to on setting up a SRAM EX1 drivetrain in particular, but the same steps will apply to all SRAM 11-speed derailleurs.
If the derailleur has already been fitted well but still isn’t working properly, it might be the case that it just needs a few tweaks in order to run smoothly. However, it’s wise to follow this guide from start to finish so that you can rule out other issues.

First shift down to the smallest chainring. If it won’t jump down to the smallest, then release some tension on the cable using a 5 mm allen key.
First shift down to the smallest chainring. If it won’t jump down to the smallest, then release some tension on the cable using a 5 mm allen key.
Adjust the outer stop with help of the inside screw on the rear mech. Turn the screw clockwise, and the derailleur moves inwards (i.e., limiting its outward movement) and vice-versa.
Adjust the outer stop with help of the inside screw on the rear mech. Turn the screw clockwise, and the derailleur moves inwards (i.e., limiting its outward movement) and vice-versa.
Once set up properly, the upper jockey wheel should be directly under the smallest cog.
Once set up properly, the upper jockey wheel should be directly under the smallest cog.
Now it’s time to set the inner movement. Slowly click up through the gears…
Now it’s time to set the inner movement. Slowly click up through the gears…
… and then adjust the inner stop with the outside screw. You should set this so that you’re not having to actually press against the inner stop to get the chain to move onto the largest cog. There should still be some minimal play in the gear lever after shifting – if you’ve set the stop too early, the gear shifter just won’t click into position. Too much play and you’ll force the derailleur into the spokes.
… and then adjust the inner stop with the outside screw. You should set this so that you’re not having to actually press against the inner stop to get the chain to move onto the largest cog. There should still be some minimal play in the gear lever after shifting – if you’ve set the stop too early, the gear shifter just won’t click into position. Too much play and you’ll force the derailleur into the spokes.
If the chain is on the biggest cog then you can adjust the chain gap (derailleur tension). The chain gap is the distance between the largest sprocket and the upper jockey wheel, and it should be about 12-14 mm. SRAM provide a gauge, which simplifies this adjustment.
If the chain is on the biggest cog then you can adjust the chain gap (derailleur tension). The chain gap is the distance between the largest sprocket and the upper jockey wheel, and it should be about 22 mm. SRAM provide a gauge, which simplifies this adjustment.
The screw for adjusting the chain gap is found on the back of the derailleur.
The screw for adjusting the chain gap is found on the back of the derailleur.
As loads of bikes have rear end lengths that vary depending on the suspension’s movement (and therefore the chain too when the shock compresses), you need to make sure that you set the chain gap in the sag position (i.e. when you’re sat on it).
As loads of bikes have rear end lengths that vary depending on the suspension’s movement (and therefore the chain too when the shock compresses), you need to make sure that you set the chain gap in the sag position (i.e. when you’re sat on it).
After you’ve finely adjusted the derailleur, then it’s time to adjust the cable tension. If the chain isn’t moving cleanly to the big cog, then add some tension by unscrewing the screw a little. If there are problems when you’re shifting down, then reduce the tension again (screw in).
After you’ve finely adjusted the derailleur, then it’s time to adjust the cable tension. If the chain isn’t moving cleanly to the big cog, then add some tension by unscrewing the screw a little. If there are problems when you’re shifting down, then reduce the tension again (screw in).
Now your shifting has been sorted you’re ready to hit the trails!
Now your shifting has been sorted you’re ready to hit the trails!

Possible issues

If you’re still having issues after sorting out the shifting, then here are some potential issues and how to tackle them:

– Gear hanger bent: If the gear hanger is bent, then the derailleur won’t be aligned properly with the cassette, which means you’re likely to have problems shifting and a chain that jumps off the cassette. So while you’re out riding, make sure you’ve adjusted the top stop so that the chain can’t jump into the spokes – but really, it’s time to fit a new gear hanger.

– Gear cables (inners and outers) are worn: If the gear hanger is bent, then the derailleur won’t be aligned properly with the cassette, which means you’re likely to have problems shifting and a chain that jumps off the cassette. So while you’re out riding, make sure you’ve adjusted the top stop so that the chain can’t jump into the spokes – but really, it’s time to fit a new gear hanger.

– Gear outer too short: If the cables are aged or corroded, then there’ll be friction and imprecise, awkward shifting or it just might not work at all. We recommend changing your gear cables once a year. (Plus, we’d lubricate them every couple of months, especially if you’re riding in the wet).

– Stiff chain links: If the chain does run smoothly over the cogs and there’s added noise, then it’s perhaps down to overly stiff chainlinks. These could have been bent through contact with a rock or just have rusted through lack of care. Check out this article on how to look after your chain so that you’ll avoid this one in the future.

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