How To Adjust + Index Your Gears – Mountain Bike Maintenance Tips

How To Adjust + Index Your Gears – Mountain Bike Maintenance Tips

Getting your gears shifting quickly and
smoothly should be quite an easy job to do, but it takes a little bit of knowledge
about how that system works first. A clean, well-lubed chain will make a big
difference to how easily that chain shifts up and down that block, so do that
first. Both front and rear mech work on the system of having the correct
cable tension so both your upshifts and downshifts are quick. So
let’s break that down to three parts. First your cables,
then we’ll look at the limit adjusters. Then we’ll actually
look at the cable tension. So, first thing to look at is the actual condition
of your cables. If they’re worn with loads of friction in them, you’ll never get
those gears to work very well. So, what I do, is I’ll feel for it on the shifter.
If there’s a lot of friction when you’re pushing through that shifter, that’s
a sign that you’ve got a lot of friction in there, or if it’s a bit slow going down
the block, that means the cable’s not returning nicely with the spring
on your mech. If there is any friction in there, now is the time to stick a
new inner cable in, if not the whole system. If the outers are kinked, you’ll
never get them working nice and smoothly either, so that’s when I just replace
the whole gear, cable in it and outer. So, going down to the rear mech, let’s
just have a quick look to make sure that that mech is nice and straight, also
that your rear hanger isn’t bent. So if you look down that cage, it should
be absolutely parallel to your cassette, you know, and nice and square to that back
wheel. If that’s still twisted or pulled out, that pretty means that you’ve bent
that hanger. That’s going to affect your shifting as well, so make sure that’s
straight first. I’ve undone that pinch bolt that holds the cable into that rear
mech, so now, pedaling the bike forward, just push that mech up and towards
the rear wheel and then let it go, and that mech should return nice and
quickly. If there’s a bit of friction in that mech as it drops back down, that’s a
sign that that mech might be a little bit damaged or bent, so that’s not
going to help your shifting either. So now let’s look at the limit screws.
Bear in mind that these don’t affect the actual shifting of the rear mech, they
just limit how far it moves up and down. So if you have that limit screw not set
tight enough, that’s when your mech can go too far and go into that rear wheel, so
that’s something to pay attention to. And the high and low works just like
a car, so a high gear is fast speeds, low is slow speeds. So that’s your
low gear and that’s your high gear, and you’ll have a high and a low
limiting screw on that rear mech. So if we start with the high adjuster,
remember to leave that cable unattached. And as I’m pedaling the bike forward, you
can see the chain is actually trying to jump off the bottom tooth on my cassette,
which means that this is mech is too far outboard. If I give that mech a little
push, now you can see it runs nice and sweetly. So, I need to wind that high
adjuster in clockwise slightly until I get that chain running nicely on there. It’s
not trying to pull it off the bottom of the cassette. On SRAM, the high adjuster,
confusingly enough, is the other side. So I’ll stick half a turn on there, and
see how that runs. Still wants a little bit more, so another half turn. There
we go. Give that mech a push, let it drop back down. If you wind it too
far on, you’ll notice your chain won’t come nicely down into the easiest gear,
so you want to take a little bit back off, just so your chain comes
into that gear, but no further. Okay, so now we’re going to look at the
low speed up at the top of the cassette. Like I said before, that’s going to stop
me from over-shifting and pushing that mech into that rear wheel. You can also
get that if it’s not adjusted correctly, maybe on a big landing or a big hit
on the bike, the mech can jump. If you’ve not got that adjuster set
properly, that mech can jump into that rear wheel, snap your mech, snap your
hanger, and do some damage to that rear wheel. So make sure this one’s set nice
and tight so the mech can’t go too far. So, pedaling the bike, I’m just going to
push that mech up towards that top, and as you can see, mine is going too far.
That chain’s jumped over the back of the cassette and going into that back wheel,
so I need to stick some adjustment, wind that low adjuster clockwise in to
limit that mech a little bit more. Okay, so I’ve put a couple of turns on
that low adjuster, pushed the mech up. By now you can see it’s not quite moving
far enough, so I’ve put too much on that low adjuster. So I need to back it off
half a turn to make sure that chain goes all the way up, but no further. There
we go. Okay, so now the mech is set up so you’re getting the
full range of gears, and it’s going no further. Now I’m
going to put the cable back on, and I’ll double check those again
once the cable’s back on. Okay, so, finally, we’re going to look at the cable
tension to get those gears working nicely. So, with your cables still unattached from
the rear mech, let’s go up to the shifter and just set this adjuster so it’s
clockwise all the way into the shifter, and then go back out one turn. So, you’ve
got a bit of adjustment both out and in, to just give those final adjustments
of tension on that cable. So, make sure your shifter is down into
the highest gear, so I’m all the way to the bottom of the block. Now, I’m just
going to pull ever so gently on that cable to give it a little bit of tension,
before I then tighten this bolt. So now, we’ve mounted the cable through the
rear mech, all the final adjustments come from this barrel adjuster up on the
shifter. So, let’s have a run through the gears. I’m pushing to go up to my
lowest gears, and I’ve given it a push, and it’s not actually moved the chain up.
That means I need to wind this adjuster anti-clockwise, to put some more tension
on that cable. Okay, so I’m going to give that barrel adjuster half a turn
anti-clockwise to put more tension on that cable. Still not quite doing it,
so let’s give it a little bit more. Try again, there we go. It’s
going up and into that lower gear. It’s still a little bit slow, so I’m going
to put a little bit more tension on, maybe a quarter of a turn. Try
again. There we go, nice and quick on those shifts
towards the lower gears. So, let’s now check the shifts back down
the block. If you put too much tension on that cable, yes, your shift’s going
to the lower gears might be quick, but that’s going to maybe slow down the
ones coming down the block. So let’s double check that. See how it’s a little
bit slow coming back down? That means I’ve got a bit too much tension on that
cable, so I’m going to give that barrel adjuster half a turn back clockwise,
take some tension off, and that’s better. So now, we can see we’re getting quick
shifts both ways, which means that that tension’s set nicely. I will double check
those stop adjusters by shifting it up right to the top, nice and quick, and make
sure it doesn’t go over the back of the cassette, and then fire it down to the
high gears, and then make sure that that chain, again, doesn’t jump off the bottom.
Just remember that you do need a nice, clean, gear cable in there. If
there’s any friction in that cable, you might get the gears working one way
nicely, but probably not the other way. So there you go, there’s setting up
your gears. It’s quite a simple process, really. Big one is just definitely make
sure you get those stop adjusters right, so you don’t risk any damage to your back
wheel, or an expensive one where you rip out the mech and do loads of damage, so
get that sorted. If you found this video useful, click “Like” down below, and
also for any of our other mechanicals, you can click our mechanical playlist up
here. Or for our pre-ride checks on your bike, click down here. Also, you can
always click on me to subscribe to GMBN.


  1. Thanks man
    Follow ur tips one by one all falls in place perfectly now
    Nomore stupid auto shifting while riding trails

  2. Whatever direction I turn my Low Adjuster, my casette is further limited to my higher gears. Am now single speed. Need help.

  3. Yet again, this has been invaluable sorting out the gears on my MTB, and my daughters! Cheers GMBN 👍

  4. Thank you Neil and GMBN! I finally set up my new bike thanks to your excellent instructions! It was much easier than some other videos on YT would make you believe! The B screw threw me off a couple of times (it has significant effect on a 1×11 set) but I finally got it right! 🙂

  5. You forgot the derailleur adjustment of the gap between the chain and the highest cog, if i may say so sir !

  6. wow, you seem to be the only who knows what he's doing. The other "professionals" constantly turning the barrel back and forth for every gear as if there is some kind of magic spell make it stay there for each gear

  7. Spot on!! No way was I taking my bike back to the dealer for such a simple task. Great vid as always. Thanks GMBN

  8. I noticed that at the end of the video you stopped the rear wheel with the left braking lever, why did you turn between them?

  9. I realize this is a older video. But do you have any issue when "back-pedaling" and the chain drops down the next cog? How do I remedy this, besides the obvious comment "to not back-pedal"? FYI; This is a brand new bike, YT Jeffsy, 1×11 e-thirteen cassette with SLX derailleur. I have performed this method on my other bike, a Airborne 29'er hard-tail, and it worked great! Thanks Neil.

  10. Best video out there explaining how to index your gears. Only thing missing was the B screw adjustment. I installed bigger cassette and had trouble adjusting the low limit screw. After doing some research I found out I needed to replace my B screw for a longer one. Purchased one for a couple of $$ online and replaced stock, shorter screw. Adjustment and indexing was a breeze after that. Thank you!

  11. Hey, I just upgraded my bike that has a 9sp I had a 11-34 but bought a sunrace 11-40t cassettes but I’m having trouble with I derailleur won’t go to the high gear I already was play with the screws and won’t go up? Do u know what derailleur will work with this set up 30t front and 11-40 in the rear if u know what derailleur works can u let me know thank you

  12. Excellent. Engineer for over 40 years but always dreaded 'doing my gears'. I watch this vid before starting, every time; life's much easier now. Marvellous.

  13. Just watched this to see if anything had changed in the last 20 years since I bought a new bike. Looks like not really. Excellent video lads,

  14. Gmbn are the only maintenance videos I trust! I finally got my derailleur working perfectly.. thanks! Can I ask why you prefer your rear brake lever to be on the left handlebar? Is that common?

  15. I get my gears all working when the bikes up in the air. Then when I put power through it in high gear the chain grinds and jumps

  16. I have a problem maybe y’all can help me fix! The cable that goes from my shifter, through the housing and to the derailleur keeps getting pulled back into the housing or on the shifter end and it gets super tight on the derailleur side and it obviously messes with the shifting during the ride. I do this pretty much every time I take it out for a spin. I pull the cable out from the housing on the derailleur end to give it slack and it works fine but after a few turns, jumps, etc it gets pulled back towards the shifter or into the housing and all the slack I gave it is gone again. Any ideas? Help please.

  17. I watched several videos while trying to adjust my Box Two derailleur, but this was the easiest to understand and worked perfectly. Thanks guys !

  18. Cheers GMBN this really really helped me, great explanations and didn't overwhelm us with information and big words. Best video on indexing and shifting issues I've seen. Thanks guys!

  19. I,d rather work on the Hadron Collider than my rear mech, its a complete mystery what goes on back there!!

  20. Having watched a few tutorials but did not clearly understand, this is the one that finally made me got it easily. Thank you

  21. I recognize this is an old video (so may not get an answer), but my indexing works excellently on the bike stand but really poor when riding. The gears struggle to move down the block. Any tips please?

  22. What happens if the deralier doesnt go down to the h8ghest gear mine sits on the 3rd highest does this mean all i jeed to do is adjudt the cable

  23. Only thing I felt was, during final index adjustment, he was turning the adjuster too much at once. I turn it 1/8 th of a turn and recheck, instead of the half or 1/3 he used. With the amount he turned, it would be easy to go too far each time and get confused as to what's going on.

  24. Hi I just got a new bike today( marcooltrip mz) but the gear at the rear end does not shift between the highest and lowest. It only moves between the middle five. What do I do

  25. So it took way to many pauses and replays than I'd like to admit but I FINALLY got my beautiful Uzzi with Shimano XT shifting perfectly
    Thank you guys for all the help, the tutorials, the challenges, all your videos are fantastic!

  26. The British invented the English language, so why do they speak it so badly? Just kidding, good video mate

  27. The GMBN site is great. I'm learning so much from various videos the site provides and it has helped me to move from a casual path cruiser to an interest in more difficult trails.

  28. excellent video.. u just made my rides back and forward to work alot more.enjoyable now that my gears are smoother.. many thanks!! 😉

  29. Thanks for the video. How is it that you make this sort of thing look so easy?! This morning, having replaced my shifters, I tried to follow this procedure. But, straight away, I have a problem! With the cable released from the pinch bolt at the rear mech, I can set the H-limit. Still with the cable loose, I tried to do what you did and move the mech by hand to shift the chain up onto the largest cog. But, try as I might, the chain just will not go onto that cog and there is no more movement in the mech! Any ideas as to what might be the problem? Many thanks

  30. What In love about this video is it makes what many believe is a perplexing job very easy. I just indexed my gears in 10 minutes and this was my first go. Thanks GMBN

  31. Thank God was watching Americans and was about to jump out my window but this was not complicated or prolonged like all the other videos thanks still missed my work but at least I can get there now👍

  32. I have new bike with 11×1, it changes gears nicely and without any issues but chain slips sometimes when I pedal hard, any ideas what can be issue please? Many thanks for any advices

  33. Just put new gear cable in cause it snapped on my last ride. Limit screws are properly set but now my 10speed sram shifter only have 7 clicks? Any subgestions?

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