Adjusting the B angle
Adjusting the B angle

How to adjust your rear derailleur

Adjusting the rear derailleur is really not that difficult. Three little screws and the cable tension bring precision back to your shifting. See for yourself.

There is nothing more irritating than a badly adjusted rear derailleur. The chain does not move smoothly from sprocket to sprocket, shifting becomes a lottery, not to mention the unnerving noise. This is bad news for all the components involved, as wear and tear increases. Apart from that, your fingers need more and more force to execute gear changes. However, it is not difficult at all to adjust a rear derailleur. We will show you in a few, easy steps how to set the limits of the rear derailleur and how to adjust the inner wire tension. The photos show a mountain bike, but the concept for rear derailleur adjustment is pretty universal. So dear roadies, bear with us, it works the same way on road bike.

Note

This short manual is intended for fully installed drivetrains. Hence the inner wire is already under tension and can be adjusted using the barrel adjuster at the gear shifter. Please turn the barrel until it is half-way screwed in. This way you can later use it properly to adjust the inner wire tension.

There are other factors that determine whether your drivetrain will perform gear changes smoothly. A bent derailleur hanger, wear and tear on cable housings, inner wires, derailleur, cassette and chain can make adjustments impossible. We will show you in a later post how to check for worn components that need replacement.

We worked with a new Shimano rear derailleur in this post. Other models and brands may vary in design and layout of the screws. However, their labelling and function is essentially the same.

Adjusting the inner wire tension using the barrel screw at the gear shifter

Adjusting the inner wire tension using the barrel screw at the gear shifter

How to adjust the rear derailleur?

To adjust your rear derailleur, you have to perform two tasks: Set the limit screws and the inner wire tension. We will start with the former.

Your derailleur has two limit screws. For the outer limit, you adjust the H-Screw, so your chain does not fall between the cog and the dropout and for the inner limit, you turn the L-Screw, keeping the chain from derailing towards the spokes. Let’s look at how this works exactly.

Setting the limits

Screw Direction Problem Effect
H clockwise Outer limit Derailleur moves to the left
H counter clockwise Outer limit Derailleur moves to the right
L clockwise Inner limit Derailleur moves to the right
L counter clockwise Inner limit Derailleur moves to the left

Outer limit

To adjust the outer limit, move the chain to the smallest sprocket. In this position, the upper pulley is supposed to be aligned with the smallest sprocket.

Left: Limit set correctly - Right: Limit set incorrectly

Left: Limit set correctly - Right: Limit set incorrectly

Should this not be the case, use the H-Screw to move the limit. Turning the screw clockwise, moves the derailleur limit to the left, turning it counter clockwise, moves it to the right. In the end, the sprocket and the upper pulley should be aligned perfectly.

Adjusting the outer limit

Adjusting the outer limit

Inner limit

Move the chain to the largest sprocket. Again, the upper pulley should be aligned with the largest sprocket. If the limit is set too far towards the spokes, turn the L-Screw clockwise and the derailleur moves to the right. Should the limit be set too tight and the chain cannot climb to the largest sprocket, turn the L-Screw counter clockwise until the sprocket and pulley are aligned perfectly.

Adjusting the inner limit

Adjusting the inner limit

Adjusting the inner wire tension

To adjust the inner wire tension, shift slowly through your gears back and forth. Pay attention to the chain and how it moves from sprocket to sprocket. If it falls immediately into place, all is fine.

Should the chain not want to fall easily onto the next smaller sprocket, you have to lessen the tension on the inner wire. Turn the barrel screw on the gear shifter/derailleur clockwise.

Should the chain not want to climb easily onto the next larger sprocket, you have to increase the tension on the inner wire. Turn the barrel screw on the gear shifter/derailleur counter clockwise.

MTB inner wire tension adjust

Road bike inner wire tension adjust

B angle adjustment

The angle adjustment determines the distance of the upper pulley from the largest sprocket. This distance has to be set to between 5-6 mm. Turning the B-Screw clockwise increases the distance between the pulley and the sprocket, turning it counter clockwise moves the pulley closer to the sprocket. The closer the pulley is, the harder shifting becomes as the sharper angle requires more force. Is the pulley too far away, shifting becomes unprecise.

Adjusting the B angle

Adjusting the B angle

Screw Direction Adjustment Effect
B clockwise Distance between pulley and sprocket is too small Derailleur moves down and back
B counter clockwise Distance between pulley and sprocket is too small Derailleur moves up and forward

You are done

This was it. If you have followed all the steps correctly, your rear derailleur should shift perform precise gear changes now. If this is not the case, there might be something wrong with one of the components involved. Don’t hesitate to contact us through the comment section in case you have doubts or questions.

If you want to find out how to adjust your front derailleur, click the following picture: