- Ah, disc brakes. The hardest to look after
than rim brakes. Possibly just a little bit.
But the main reason for that is because
they are different to what most people are used to.
But with the tips and the hacks which are coming up
You should be well on your way.
[Upbeat Music Playing]
Firstly, let's have a look at the very annoying case
of disc brake rub, essentially where the brake pads are
rubbing against the rotor. A few things to check,
but the first one you should do is simply to loosen
the mounting bolts here.
Slacken them right off, then hold your front brake on.
This is the left brake front bike at the moment.
Hold it on nice and tight.
Do the whole system back up again,
preferably with a torque wrench like this,
and give the wheel a spin and see if that has solved
your problem. In a lot of cases it will have done,
but with flat mount discs in particular
it can be a little bit more complicated.
For the hack, you are going to need
some kind of business card. I've taken Si Richardson's,
And you're also going to need to take the wheel out,
which for this particular bike is a 6mm Allen key.
Drop it out briefly, then you're going to take
your business card and bend it over the rotor like so.
And once you've bent your card into shape,
insert it into the calliper.
Then, put your wheel back in.
(upbeat music playing)
Then we are going to loosen the calliper off again,
as we did before, and the width of that business card
should be just the right size
to space the pads out nicely.
So pull your brake on again. Should be all nice and centred
and then you can do it back up
with your torque wrench again.
Then you are ready to drop the wheel back out again
and remove your business card. And then hopefully...
And you put your front wheel back in.
And tighten the whole lot up. Everything should be
perfectly centred,
and no sign of any disc rub.
Perfect disc brake hack.
(music playing)
Now, it's fair to say that for the majority of us
disc brakes are relatively maintenance-free,
and that is a fair reputation, but if you ride a lot
in bad weather there is something else
that you need to know about and be aware of.
And that is sticky pistons. The pistons are essentially
what's inside the calliper here, which pushes the brake pad
onto the rotor, and they can occasionally become sticky.
They're in their own little oil bath,
and you'll be able to tell by looking inside them.
It won't necessarily be evident
just by pulling the brake lever on here.
So, to get access to them, you need to remove the wheel,
and also remove the brake pads.
Then once you've got the pads removed
and the pistons exposed, you want to pump the brake lever
a few times to pop them slightly out.
Make sure you don't go over the top when you're doing this
because it's very easy to pop the pistons out completely,
and that would mean a full re-bleed.
So, just a few times until you've got around
three to four millimetres exposed on both sides,
at which point you'll want to get yourself
some alcohol spray and a nice, clean rag,
and clean the non pad-facing side of the piston.
So, effectively, the bit that's around the edge
that needs to be nice and clean when it's going in an out.
[Upbeat Music Continues]
If one piston is particularly sticky,
what you might find is that the other piston has come out
and is exposed, but one is left hidden.
And that situation, what you want to do
is spend the first part of your time
cleaning the exposed piston, and then using something like
a plastic tyre lever, push that one back in.
And then with the fluid that's in the system,
it should be enough to push the slightly sticky piston out.
Then, once they're all cleaned and dried,
push the pistons back inside the calliper
using a plastic tie lever, and then give the brake
a few pumps, just to check that they are now moving up
nice and evenly.
Then you just need to put the brake pads back in like so,
and hopefully that will have solved your problem.
And then stick your wheel back in.
Looks nice and aligned already.
Perfect.
Right. Next up is a hack which comes from our very own
GCN mechanic Tom. Not Tom Last, you understand,
but someone that actually knows what they are talking about.
So, if your brakes are starting to feel a bit spongy,
The first point of contact with the pad at the rotor,
you can then pull the brake lever on it
significantly further.
Then it might be that the whole system
needs to be re-bled, which is quite a big job.
However, if that has been done fairly recently,
you might want to check this next hack out.
For it, you are going to need a bleed bucket,
and also some fluid which is specific to your brakes.
First up, you're going to want to put your brake-specific
fluid into the bleed bucket.
Fill it up around about a third.
And then put that to one side.
Then you want to expose the bleed port screw,
which would be underneath the rubber hood here,
and undo that with a 2.5mm Allen key
on the Shimano brake.
Pull that out, put it carefully to one side,
and then screw the bleed bucket in.
Right. And then to do the actual hack part of this
we're going to take the bike out of the stand.
And put it on the floor. Right.
Then, take the top of the bleed bucket off
and remove this plunger from inside.
Now, squeeze the brake lever on and off a few times.
Do it as tightly as you can.
And what you should be encouraging is any air in the system
to be coming up towards the top.
And you might, in fact, see a couple of bubbles
coming through the fluid in the bleed bucket there.
Now here's the actual little hack bit, though.
Take the top part of the bleed bucket and replace it,
and then just gently squeeze the brake
whilst also gently tapping the front wheel
up and down on the floor. And that will give
an extra bit of encouragement to any air
which is trapped in the system, which could be well be
the cause of your spongy feeling brakes.
And hopefully that will have solved your problem.
Don't forget, though, to put the plunger back in
before you unscrew the bleed bucket.
Otherwise, you're gonna get fluid everywhere.
Right. Then, back on with the screw.
It will need a quick wipe-over.
Hood back on.
And it feels a lot more solid.
Now, if it is the rear brake which is feeling spongy,
then when you are doing it you can do exactly
the same method,
but when it comes to bouncing the bike up and down,
use the gravity to your advantage
so that the air comes upwards.
The bike here, just bounce it gently at that point
whilst pulling the brake lever on it.
And those three hacks should solve a lot of your
disc brake problems. One more thing that you can try
if you are finding you're getting air in the system,
is to focus on the points where air might be getting in.
So, for example, the part here which connects
to the cabling parts here. Expose the bottom part
which normally got a rubber seal over it,
and on this case it is an eight millimetre spanner there,
and then a nine millimetre here, and just check that these
are nice and tight. You can also see
whether there's any fluid around there.
Wipe that off with a rag. Go out for a ride.
Because everything will still be safe,
and then expose it again and see if there is
any more fluid starting to leak out.
And another final tip, which you might not think about
if you are new to disc brakes as I was a few years ago,
And that is when you are travelling, you want to try
and prevent the brake pads coming together
and the pistons coming out. So to do that,
you can get specific spacers like this,
which you can put in before you go into your bike bag.
Or, if you haven't got one, you can simply use
a couple of business cards with a very thin coin inside.
And that should do the trick nicely.
I would love to know how you get on with all these hacks.
You can do so by letting us know
in the comments section down below.
And if you'd like to see Si Richardson
taking a first look at the Dura-Ace disc brake group set
a few months ago in 2017,
you can find that in the bottom corner just down there.
On the other hand, if you want 10 more
general cycling hacks, you can find them
in the top corner up there. And make sure you subscribe
to the Global Cycling Network. It is free to do so.
All you've got to do is click on the globe.