How To Shorten The Chain On Your Mountain Bike

– Hello sports fans. Today we’re going to be
taking a look at our chains, how to ensure they’re the correct length and how to fit a new one. This is really important to optimize both performance and safety. (whooshing) (clanking) For this video, all you’re going to need is a chain-breaking tool as
well as a brand new chain. You do have the optional
luxury of quick link pliers, but they’re not strictly necessary. Now when we’re replacing our chain, we can potentially cut
it to the same length, but before we go rushing
in with our golden ticket to drive train bliss. (sparkling sound effects) How do we know that this
chain is the right length to begin with? What we don’t want to do is go off a chain that’s incorrect and then potentially cut a new chain too short. The way I like to do it is
we go off a thing called B-Tension. B-Tension is basically how
far away is the adjustment that affects how far away
that top jockey wheel sits from the teeth of the cassette. Now, B-Tension isn’t a
substitute for chain length, but it’s kind of a set and forget and it’s really important to
get it correct the first time. The best way to do this,
or my preferred way, is I go into the second
largest cog of the back and I’m going to look
through and what those teeth at the top of the jockey
wheel just a millimeter or two away from kissing the
teeth of the largest cog. This means when you ride
up into that biggest cog, that lowest gear, it’s going to be nice
and clear of each other. If you’re getting a
(trilling sound) as you go through the cassette, it
means that there isn’t enough B-tension, but conversely, if you have too much and
there is a country mile between the two, that is going
to have an adverse affect on performance and like
I said, B-tension is not a substitute for correct chain length. (upbeat music) Now, on this bike, the
chain length is actually already pretty good. There are two main ways
you can visually inspect to see if the chain
length is indeed correct. The first way is you go into largest cog and your biggest one in the front if you’ve got a double or a triple. This is when the system
is under its most tension. And you want to make sure
that the chain line is kind of perpendicular to the ground. The other way, and
personally my preferred way, is when you go into the
smallest cog at the back and the smallest cog at
the front, yet again, if you’re running a double or a triple, and this is where the system
is under its most slack, and you want to make sure its just coming under tension there. Now why would you want to run
as much slack as possible? Surely, devil’s advocates would
say that you actually want the shortest chain possible to
keep vibration to a minimum. However, full suspension bikes undergo a thing we call chain growth. Now what does this term mean? It means as the bike goes into its travel, the wheel base of the bike
extends, putting more tension on to the system. So, if you have the chain
as short as possible when you go into the bike’s travel, you can actually, really
have a detrimental affect on your suspension’s performance, which is obviously what we don’t want and under a large compression, especially ln these
bigger cogs at the back, you can either rip a mech clean off, or snap a chain, which
is going to leave you up a certain type of
creek without a paddle. (clicking chain sounds} (upbeat music) Now, as we can see, when
it’s in its smallest cog, the back and the system
is under the least amount of tension it will be under. It’s actually still, just
taking some load there lifting the chain off
that front jockey wheel. This is really, really important. If the chain is grounding out
on that jockey wheel there, it’s not under enough tension. Now, please do this sensibly. Don’t go cutting once and
worrying about it later. But, as the old adage
goes, measure it twice, measure it three times. There are no excuses not
to take it step by step and ensure it’s the correct length. (techno music) How long should a chain last? Well, there are huge amounts of variables: how you use your gears;
what you lube them with; where you ride will all have an affect on the life of your chain. There isn’t really a way
to inspect it by eye. You do need a chain wear tool, but those tools are really good and they can actually premeditate when you are going to start wearing out those cogs in the back. Anything over .75 is
getting into the territory where these will be so sufficiently worn that a new chain will slip up. So if it’s above .75,
really start considering to swap out that chain. Sometimes, it’s even .05, but check with your chain manufacturer. So, first things first,
let’s remove this chain. (rhythmic music) There are two ways to do this. We can either use quick link pliers. Just snip that one and open it up, or if we’re just throwing
the chain away anyway, we can use a set of chain breakers. To make your life easier, put
the clutch on the rear neck, so we pull the cage
forward and just activate that little button there. This gives us plenty of slack to work with and using our pliers here, we’re just going to snap it open and we can pull this chain like so and if we lift it behind the cassette, we can actually just pull it up. (uplifting music) So this is our brand spanking new chain. Now a couple of things
to really note here. First of all, this is a
correct speed for a system. A 12 speed chain going
on a 12 speed cassette. Secondly, some chains, mainly
Shimano, are directional. So, they do it, the writing
is facing out towards you on the drive side. I personally like to start at the front, so we can get it correctly meshed in with our narrow-wide chain ring. If you’re running a one
by, you can just drive it round there. If you’ve got a chain device, you’ll want to just gently feed it through. There we go. Now it’s also got a bit
of slack, just because there’s nothing more annoying
than pulling the chain as you get it through the cage here and then it comes off this end. The next thing is, rookie
error time, please make sure it goes the correct way. The amount of times I’ve seen
people loop it over there, under here, you know,
just got to go nicely through the stay and we’re going to drop our chain in,
straight through and down, the jockey wheels of the derailleur cage. Another thing that is
also really worth noting is a very rookie error, and
pretty much every mechanic in the world has done it at
some point, is you accidentally there’s a little plate here
and some people accidentally route the chain in front of
that plate, if you can imagine. And what that means is,
although it might shift, it might work, it’s going to
make a hell of a lot of noise and it’s incorrect and it
will cause you problems later down the line. This will recoil like a desert eagle. So, go easy, let it go gently, cause otherwise what will happen is you’ll get a lot of flick in the chain, probably lose an eye, it
will just be a disaster. So please be sensible. And then we’re going to visually line up which parts of the chain we break. So if you imagine along here
I’ve got the inner plates and the quick link access to outer plates, so I’m looking to break the
chain, that’s another set of inner plates such as that there. Now, please, I’d rather
you do this, kind of twice, and get it done properly
then just going too short out of some rush, we’ve
got plenty of time. So if I was to do it to
that one, well, that’s going to be too loose, I can tell
you that straight away. So the next we’re going
to go to isn’t this one, it’s actually this one, cause like I said, the quick links replace this
outer parts of the chain, those outer plates. So we’re going to break the chain there. That is, that’s the one. I’m not going to remove
my hands from there, you know you can prise this chain out of my cold dead fingers, I’m not going to lose that link. So, once you’ve got it,
please don’t lose it. And we’re going to put our chain into our chain breaking tool
and just drive it through. With your chain breaking
tools, please make sure that it’s sat in there properly, maybe check the instructions. There’s actually a lot
of force, you’re putting through quite a small rivet there. So what you don’t want to do is leave it so the chain isn’t actually
slotted incorrectly whichever orientation it is. It can basically damage
your tool, which is well it’s a bit of a nuisance really. I’m actually going to
put the clutch back on on this SRAM system to
make sure it’s all good and just gently, one at
a time, putting these quick links on and obviously
on different sides. We’re just going to,
very gently, we’re not, don’t feel we need to
snap it yet, we just need to hold it yet again,
holding the chain just so and gently, that’s the important bit, let our clutch take up the slack. And, well I’ll be, that
looks pretty good already. So, I want to really make sure, that this quick link is,
you know, engaged properly. Now what’s the best way to do that? Some pliers can force it back there, pulling the quick link apart. My personal way to do it is actually to spin the wheel, so just
gently going through the gears and once that quick links
you’re going to hear it click through the jockey wheels there. There’s one, two, and
then over the cassette and here it is here (clicking sound) and by holding the rear tire and applying a moderate
amount of force to the crank it just pops in. Something I would suggest doing, and it really, really can pay dividends when you’re installing a brand new chain, to absolutely confirm
beyond any reasonable doubt, that is correct can be
worth, letting the pressure out of your shock or
maybe removing it entirely and cycling the bike through it’s travel to make sure the chain
whilst in that largest cog in the back isn’t going
to cause you any problems or limit the drive train’s
movement in any way. And hey presto! What do you know? I have a brand, spanking
new chain ready to rip on my bike. Now if that quite hasn’t
satisfied your appetite for maintenance videos, click down here to see a really
comprehensive tubular setup where I go through the whole process from start to finish. And if that sounds quite up your street, I actually serviced this
very shock in real time in front of your very eyes. So do check out that video there and we will talk you
through the whole process. As always thank you
very much for watching. Please don’t forget to like and subscribe and get into the comments
below to let me know how you got on and perhaps
there’s something I’ve missed. Cheers guys!