- 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.
