- Coming up, we've got five hacks
to make setting up your gears easier,
and also cure your shifting headaches.
First up, correctly setting the limit screws
on your derailleurs is a really important job.
Potentially saving you from some very
expensive mechanical disasters,
particularly here on the rear derailleur,
and our pro hack is to actually set our
limit screws before we even put a cable in.
Firstly, we will look at the high-limit screw.
Technically this bit will be no different
from normal when you've got your cable in.
You simply stand to the rear of the bike,
and you eyeball it from the back.
You want to screw or unscrew the high-limit screw
until the top jockey wheel is resting
just outboard of that bottom cog.
Shouldn't make any noise, but being just outboard
will help you shift into that smallest gear.
To set a lower-limit screw we're
gonna move the derailleur by hand,
pushing on that cage with out thumbs,
and shifting until we're in our largest cog.
That way, when we set the low-limit screw,
we know exactly where the limit of the derailleur is,
in respective of where the cable might be limiting it.
It's like an insurance policy, basically.
Pre-stretch your cables.
You want to do this before you actually index your bike,
otherwise, as soon as you get on
and ride around for two minutes,
you're gonna have to re-index it anyway.
The trick is, you clamp your cable and then,
holding your derailleur firmly with one hand,
to stop it moving, you click through the gears.
Only a couple, that's all you need.
You don't want to actually force anything.
Because technically we're not really stretching our cable.
What we're doing is making sure that all the
cable ferrules sit squarely and compress
as much as possible onto the cable outers,
and then they sit firmly in the cable stops.
It will be tempting if you've got external cables to
actually pull on the inner cable itself
in order to do this stretching.
But there is a risk that you actually kink the cable.
So, definitely safer to do it that way.
How about this for an indexing shortcut?
Making the whole process just that little bit faster to do.
Now we've got our pres-stretched cables,
I want you to shift from the smallest
to the second smallest cog at the back.
And then, shift back down, without moving the pedals
so that your shifter is effectively in it's hardest gear.
Then, you need to unclamp the cable and pull it tight,
not exceptionally so, but under it's own natural tension,
reclamp it, and then when you move the pedals,
the chain should go back down into your smallest cog.
At this point, while it might not be perfectly indexed,
it's gonna be pretty darn close,
and certainly much, much closer than
if you were to do it by guesswork.
Rumour has it, that this is in fact the way
that Mr.Shimano himself wanted people to index their gears.
Setting the cable tension correctly
on your front derailleur can be a fiddly process,
especially if you don't have some form
of barrel adjuster somewhere on the cable,
but this neat little hack gets around that problem.
Firstly, before you even clamp the cable,
I want you to put your bike in your lowest gear.
And then, we're gonna use our lower-limit screw.
You screw it in until the derailleur is just
starting to press the chain against your outer chain ring.
It's at this point which you clamp the cable, and then,
when you screw the lower-limit screw
out to it's correct position,
which is one or two mil, onboard of the chain,
then you should have almost perfect cable tension.
This one isn't so much of a hack as a headache reliever,
because it might be that no matter how hard you try,
no matter what you do, you just can't
get your gears to work correctly.
And if that's the case, it may well be because of alignment.
If you've had a crash, for example,
or your bike's just toppled over and landed gear-side down,
you may well have bent your gear hanger.
That's the bit that your
rear derailleur actually bolts onto.
To check, what you've gotta do is
put your bike in it's easiest gear,
and then standing behind it, you simply eyeball it to
see whether or not the rear derailleur is hanging straight.
Generally if it is bent, it will be bent
in the direction of the spokes.
And if it's bent badly, you probably already know about it,
because it would have bent so far that the derailleur would
have got caught into your spokes when you change
to your easiest gear and ripped clean-off.
You may well be familiar with that pain, I certainly am.
You can try, very carefully,
to bend your rear derailleur back.
It definitely works better on steel bikes,
or indeed heavier-duty and fairly durable bikes,
not necessarily top-end carbon.
Many top-end bikes, or mid-range bikes,
will have replaceable derailleur hangers,
which is a very good thing.
If you are gonna attempt the bend it back,
with a replaceable derailleur hanger, just make sure that
your rear wheel is tightly clamped in place.
Otherwise, you'll be putting quite a lot of pressure
on some fairly flimsy bolts that aren't really designed
to actually withstand much pressure at all.
It's gotta be said that really this may well
be a job for your local bike shop, if nothing else,
you hand the responsibility for the safety
of your frame over to them and their insurance.
And what they'll probably do is get out this tool here,
which is a DAG tool, the derailleur alignment gauge.
They'll take your read derailleur out,
bolt this bad boy into it, and then it actually uses
your back wheel to gauge what angle your
rear mech hanger is hanging at.
And then, once you've worked out
which direction it is bent in,
you can bend it back with your DAG tool.
Oh yeah, that's a good way to cure that.
There you go, five hacks that will
hopefully make setting up and maintaining
your bike's gear shifting system
just that little bit easier.
If you like maintenance videos then
make sure you subscribe to GCN.
We have a maintenance video every week for you,
every Monday, so if you subscribe
you will always be in the right place.
For a little bit more information
about the process of indexing,
either front derailleurs or rear derailleurs,
I've got videos on the subject.
Up there and up there.