Do you have to listen to this noise when you ride? Does your chain come off when
you try and shift into the big ring? If so, you need to adjust your front
derailleur, which fortunately, is, actually, a really simple thing to do.
All you need is a crosshead screwdriver and a 5 millimeter allen key. Then follow
these simple steps. All you need... Oh, [beep], screwdriver won't come out. Sorry.
Front indexing in a nutshell, there's two things to remember. Firstly,
that the limit screws adjust how far the derailer can move either out or in,
but to actually control the movement of the derailleur, that's all down to cable
tension. So limit screws limit the derailleur, but they don't adjust the
movement. That is down to cable tension. Firstly, we've got the derailleur clamp
bolt here, and that sets the height and the angle of the derailleur.
Once set, that should never move but it's always worth checking as part of the
indexing process to make sure it's in the right place. Then, we've got
two very important screws, the high-low adjustment screws.
Now, essentially, these stop the chain coming off or making noise whilst you
ride. This inboard one here, that's the L screw. That stops your chain coming off
when you shift into the little ring. And then this outboard one here,
that's the H screw, and that stops your chain coming off when you shift into the
big ring. Then, this final thing here, we've got the cable clamp bolt, and that
changes the cable tension in the system which is how your shifter relates to the
derailleur. We've got quite a crude adjustment here by loosening the bolt and
then putting the cable in, but we can do finer tuning.
Up here, we've got a barrel adjuster which means that we can dial in the
perfect amount of cable tension. As I said, if your shifting's already been set
up correctly, then the height and angle of your derailleur should be already okay.
But to check, the derailleur should sit about two millimeters above the outer
teeth of the outer ring when the chain is on the little ring. So, in this case,
we need to drop it down a little bit, and we do that just by loosening that screw a
touch there. Don't forget, any adjustment you make to the height of the mech will
therefore have a knock-on effect on the cable tension, so put your indexing even
further out. To get the angle of the mech, the plates should be parallel to the outer
chainring. Unlike the height of the derailleur, the angle actually can
sometimes move. If you ever jammed your chain quite violently in there, then it
can shift, so it's always worth having a good look at that. So once you're sure
of the height and angle, then it's time to turn our attention to the actual
indexing. I'm gonna start with this low-limit adjustment screw here.
So, first things first, put the chain on the little ring and then also on the
biggest cog at the back. Then, when the chain's in that gear, we need to turn the
L screw so that the derailleur is sitting one millimeter away from the inboard edge
of the chain. So we need to screw it anti-clockwise to move the derailleur
inboard and then clockwise to move it outboard. Now, what this does is it stops
that really annoying noise when you're in the easiest gear, and you're climbing and
also it prevents the chain from coming off when you're shifting into the little ring.
If, when you're turning the L screw here, and the derailleur stops moving,
that's because, in all likelihood, you've got too much cable tension.
So you can either slacken it off a little bit here or, better still, undo that bolt
completely and let the derailleur rest in its natural position, essentially,
starting from scratch. Next, we need to look at the cable tension, which is, as
we've said already, what actually controls the shifting part. So, while pedaling,
change down a couple of gears at the back and then try and shift into the big ring.
Now, if it doesn't go, that means you don't have enough tension in the cable,
so you can try and sort that out by using the barrel adjuster up here.
So unscrew it until it does change, or, if you don't have enough barrel adjuster to
move the cable far enough, then, again, loosen that bolt and pull the cable
tension in by hand. If it changes, or indeed overshifts, then the next step is
to turn our attention to the H screw here which limits how far out the derailleur
can move. So what we need to do is, with your chain on the big ring,
change down into your highest gear, and then we need to adjust the outer plate of
the derailleur so it sits 1 millimeter away from the outer edge of the chain.
There's a bit of a theme going on there that you can tell that.
We've now set our lower and upper limits, and we need to test it out.
So shift back into the little ring and then back into the big ring. If it won't
shift back into the big ring, because, don't forget, we've limited the movement
now of the derailleur, then we have too much cable tension in the system. So,
then it's a case of backing off our barrel adjuster here and allowing the derailleur
a little bit more leeway. Don't forget as well to test it out at different gears
at the back because that affects where the chain sits. Now, you notice that
in our smallest cog at the back in our little ring, there is still a little bit
of noise, because the chain is rubbing on the derailleur. Now, on Shimano, that's
just how it is, so they have added a little trim function into the derailleur.
It's like a half click that allows it to silence it. But, if I'm being completely
honest, I would never ever, ever ride in this gear, so it's not really a problem.
To sum up, if your chain falls off when you're shifting into your little ring or
it rubs when you're climbing on your easiest gear, then you need to tighten the
L screw. If you can't change into your big ring, then you need to increase your cable
tension by adjusting the barrel adjuster here or the cable clamp bolt there.
If, however, the chain comes off when you're shifting into your big ring,
then you need to back off the cable tension a touch and then also tighten the
H screw. Unfortunately, it doesn't always go smoothly. There is an element of trial
and error in sorting out your front indexing, but it also could quite likely
be something other than a problem with your mechanicing skills. So, here are the
most likely causes of problems with your front indexing. First things first,
sticky or gritty cables will ruin your shifting. Now, you'll feel it, because
your shifter will be really heavy, but what it also means is that the little
spring in the derailleur can't overcome all the grit in the cable.
So it struggles to move back down when you shift down, so that will manifest
itself by struggling to shift into your little ring. However, it could also be due
to corroded pivots in the mech itself, and that is because they get sticky, and then
that stops the derailer moving freely as well. If that's the case, you could
try spraying on a solvent-based degreaser and then a lube, but it's quite likely
that you'll actually just need to buy a new front derailleur. Sorry about that.
Then, finally, if both those things are working okay, and your shifting's accurate
but just slow, then it might be a problem with your chain and your chain rings.
Worn drive chain parts do mean that things slow down in the shifting department so
have a look to see whether your chain needs to be replaced and then also your
chainrings. We've got a video showing you how to do that. You can get to it by
clicking up there. Finally, it's worth saying that even the very best-adjusted
gears do have their limits. It's no coincidence why just about every
pro cyclist has a little chain catcher down there to stop the
chain coming off when they shift into the little ring. So, to get
around this problem, you just need to pre-select your gears before you
really need them. So, what I mean is don't wait until you're grinding to a halt up a
climb before you try and shift from your big ring to your little ring.
Think ahead, shift in advance, and just take a bit of pressure off the pedals when
you do try and shift, and that will help things no end. Now, your front indexing
is working perfectly. You also need to make sure your rear indexing is dialed as
well. So, to do that, watch the video up there explaining exactly how to do it.
But if you are in need of a change of cables to get your front dialed then why
not watch the video down there about how to change your cables?
Finally, so you don't miss another GCN video about maintaining your bike,
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