How to adjust rear derailleurs

Posted by tan xiao yan on

If your gears are jumping, or they are just not shifting smoothly and as quickly as you think they should, then you probably just need to adjust them. So, here’s article on how to adjust your rear derailleurs, and it should work for Camprgnolo, Shimano, and SRAM gears.

So here is how to adjust it. And if you are setting up your derailleur from scratch, then we’ve a video explaining exactly how to do that.

Limit screws

Before we get started with indexing, even if your gears have been set up before, there’s one check you should always make, and that is fort the limiter screws. So, those are these two here, and they limit how far the derailleur can move either outwards, so essentially stopping your chain from falling off this sides of the cassette, or inwards, essentially stopping your chain falling off that side of the cassette, and into the spokes. So, very simply move the derailleur by hand, then touch the shifter, and then you can see whether or not the derailleur is directly underneath the biggest sprocket and then at the back there directly underneath that one. And if it’s not, it’s simply a case of adjusting these limiter screws here. So if you turn in clockwise, this is the high limited screw, so that is the smallest cog here. And you can see the derailleur is moving simply by being delimited.


Now to actually index the gears, it’s worth bearing in mind that all indexing is done using that barrel adjuster there. So once the limit screws are set, we will leave them be. So, everything now is just going to be here. Okay so, we need to be in the smallest sprocket at the backs still, and then also stick it in your little ring as well. We will index it whilst the chain is on the little ring, and then we will check all the gears to make sure they are still working perfectly when it’s on the big ring. If there is any discrepancy between it might mean there’s an issue with alignment, but we will check on that later on.

Okay, so now, to get started, shift up one click. And you can see that nothing’s happening, it’s just making a rocket, so start turning the barrel adjuster anti-clockwise until the chain moves onto the next sprocket. Now, it’s still not going to be indexed perfectly there, but try moving it into the next biggest sprocket, and then turn the barrel adjuster until it moves into that one. And then change down and repeat the process. Still not quite there, so more tension, another anti-clockwise quarter turn, and you can see that in those three sprockets, it’s not working, so let’s try the rest of them. That looks pretty good. It is essentially as simple as that. Let’s try the big ring as well.

Remember that if the chain isn’t shift properly going up the cassette going to easier lower gears, then you need to screw the barrel adjuster anti-clockwise to make the cable tighter. And if it’s slow to go back down the cassette to into higher gears, then you unscrew it clockwise to decrease the tension and then move the chain back that way.

Sometimes it does not quite go as easily as that, so if you are struggling to index your gears, here are four tips that might help you.

Step one: replace the old cables

Now, first of all, if you can index it going up the cassette going to easier lower gears, but you are struggling indexing it coming back down, it’s highly likely that it’s down to your cable. So, when a cable gets worn, and it’s old, this gets loads and loads of friction in the system. Too much friction, in face, for the little spring in that derailleur to overcome, so the derailleur struggles to move the chain back down onto smaller cogs. So, in that instance, it is then just a case of replacing the cables.

Step two: down the worn chain

Now, second thing, if you are going to index your gears on the work stand but then when you get on the road, your gears are jumping around all over the place, then it is highly likely that it is probably down to a chain in your cassette being worn. So in that case, you probably need to replace either or both of those, which is a little more expensive, but it’s worthwhile.

Step three: change the wheel

The third thing to check is your wheel. Now, make sure that the wheel is aligned in the frame properly. That is quite a simple mistake to make, but then the other thing is if you just changed wheels recently, you might have to re-i8ndex your gears, particularly if it’s a different manufacturer. So obviously, you rely completely on the position of the cassette here. And if you change wheels and the cassette is in a slightly different place, then it is going to put your indexing out.

Step four: check as careful as possible

The final thing to check and actually, it crops up quite regularly, is the alignment of the rear derailleur is sitting straight. You can do it by eye, but the best thing to do is probably to head into your local bike shop, which will, in all like hood, have a tool like this which checks the alignment for you. So that is your gears indexed. Remember that to index and use the barrel adjuster at the back, turn it anti-clockwise to move the derailleur, ever so slightly, inboard and clockwise to move the derailleur outward. If it is not working, you need to check firstly your cables to make sure that they are running smoothly. Then if it is jumping around after you go out of the work stand, you probably need to look at your chain or your cassette for wear. Also, remember that if you are swapping wheels, then that might move your indexing in and out of line. And then finally, check the alignment of your rear derailleur and correspondingly the mech hanger as well.