- [Simon] You periodically need to replace the chain on your bike,
either because the old one is worn out, or perhaps because it's been damaged,
maybe even snapped.
- [Matt] Are you [beep] kidding me?
- Fortunately, it's a simple process. All you need is a new chain and then a chain
tool. To remove the old chain, firstly start by putting the gears in the smallest
cog at the back and also the smallest chainring in the front.
This gives you the most possible amount of slack in the chain to make removing the
old one easier. To create even more slack in the chain, I actually always unshift
the chain from the chainrings altogether. But if you've got a bike, and it works
unlike that, you can just pop the back wheel out as well.
There are actually potentially two ways to remove the chain from your bike,
and you need to inspect carefully what you currently have on there in order to find
out which one you can do. Now, what you're looking for is a link a little bit like
this one. Now, this is called a quick link, and technically you can remove
the chain without using any tools altogether. You just push the two
plates together slightly and then slide them apart. In reality, they're normally
quite stiff, and so you at least need a pair of pliers, but technically you can do
it. If there is no quick link then you're going to have to use your chain tool to
split the chain, but it's a really simple process. So simply put a link of the chain
into the chain tool and then wind the handle of the tool in towards the chain
which drives the chain tool into it and then pushes the pin of the chain out.
Now carefully pull the chain off the bike. Now, this isn't destined for the bin
quite yet. We need it for one last job, and that is to check the length of the new
chain and match it up with this one. Now over to the work bench.
Chain link varies from bike to bike because of a lot of different factors but
mainly because of the size of the gears. So you always need to reduce the length of
a new chain so that it fits your bike correctly. So take your old one,
stretch it out and then lay the new one out next to it. Now, I need to mark the
length of the new chain next to the old one and then break it using a chain tool.
But before you push the pin through, you need to make doubly sure that the two ends
of your chain are different. So by that I mean one end is a narrow end like that
then the other end is a wider end like that so they actually fit together.
Unless, of course, you are going to rejoin your chain using a quick link,
in which case both ends of the chain here need to be narrow. So, it sounds
complicated but it's not. Both ends need to be different unless you're
using a quick link in which case they need to be the same.
If for whatever reason you don't have your old chain to measure the new one against,
or you're changing the size of either your cassette at the back here or your
chainrings here. And so you need to adjust the length of the chain anyway to account
for a different of teeth, then you will find the optimum length with this method.
So you take your new chain, wrap the chain around the biggest sprocket at the back
and then the big ring at the front but bypassing both derailleurs.
Pull it tight and then add two links, and that is your optimum chain length.
See that? I'm pulling it tight, and then I've got to add two links,
so that's one link, and that's two links. So, that link there is my optimum chain
length. So now onto joining your chain. If you haven't already,
make sure that you shift your gears into the smallest ring, so down here at the
back and then down here at the front. And then thread your chain onto the bike.
Pay particular attention when it gets to the rear derailleur, so the chain goes
around the cassette like that and then loops back underneath, then over the
top of the first jockey wheel. And then pay particular attention to that pin. So
the chain has to go above that and then around the button jockey wheel, like so.
Onto rejoining the chain now. Shimano chains require a special joining pin like
this one. So, it's got a guide and then the actual chain link there.
So you start by simply pushing the thin end into the closed chain, and then take
your chain tool and push the actual link into the chain, exposing the guide pin out
the other side. And this can be quite stiff, but that is a good thing.
♪ [music] ♪
There we go. Drive it untill it's flushed, and then we leave it like that.
It's important to note that once you've used a Shimano joining pin,
you should never break the chain on that link there. Find one in many other hundred
or so links to choose from but don't break it there again. And then,
you then snap that off by using a chain tool or a pair of pliers.
♪ [music] ♪
If you're using a quick link, then you simply slide the two place together and
then lock them tight by applying pressure to the chain. It really is that simple.
And then the final point to mention is that you buy the correct width chain for
the number of gears you got. So chains are sold according to the amount of sprockets
that you've got on your cassette. The greater the number of gears you have,
the narrower your chain is going to be, so this is a really narrow 11-speed chain for
an 11-speed cassette. The other things, well, Shimano, SRAM and Campagnolo
will all tell you to only use their chains on their gears, the
idea being that they're not compatible. But third party chain manufacturers will
tend to make chains that are compatible with all three of them. So, go figure.
So all in all then, a pretty simple process, you break the old chain using
either a quick link or a chain tool. You then measure the new one against the old
one for length or use our special length checking method and reattach the new chain
using either a quick link again or the special joining pin, double checking
before you do so that it's threaded correctly through the derailleurs.
Now, two other mechanical processes that can seem daunting but are in fact simple
are replacing your bar tape and re-indexing your gears so making sure that
they work correctly. We've got videos explaining how to do both those things and
you can get to them just up there. Before you leave this video though,
do make sure you subscribe to GCN, because we have a mechanical video out every week
and you're sure to need it at some point.