Brake lever "pump up"

ChingfordMarin

Hello

I have a set of Formula The Ones from 2009 and they seem to always need a good few pumps of the levers before the bite point is further away from the handlebar. Not exactly what you want out on the trail..

I've tried bleeding them but I suppose it could be air bubbles left in the hose or im not bleeding them properly?

Any ideas what it could be?

journey_man_pro

seems like they need a very good bleed. try tapping the line and caliper while bleeding to dislodge any stuck bubbles

nicklouse

So what is happening at the disc end?

Pads moving at the start? Rotors being moved?

A bleed is one of the LAST things you should consider. First see what is actually happening.

ChingfordMarin

The brake does engage but not until the lever is 3/4 of the way to the bar (and my middle finger gets in the way stopping from me 1 finger braking).

After 2 or 3 pumps of the lever the brake engages with a little pull on the lever. (and i can just use 1 finger).

I think it does need a proper bleed as there must be some bubbles in there still.

thegiantbiker

Have you checked the wheel for wobble on the bearings? Too much may mean it's pushing the pistons back.

The Rookie

As Nick said, look at the pads, are they moving as soon as you start moving the lever, in fact if you see them more than twitch they are too far from the discs and that is your problem, not air bubbles.....

Simon

nicklouse

ChingfordMarin wrote:

The brake does engage but not until the lever is 3/4 of the way to the bar (and my middle finger gets in the way stopping from me 1 finger braking).

After 2 or 3 pumps of the lever the brake engages with a little pull on the lever. (and i can just use 1 finger).

I think it does need a proper bleed as there must be some bubbles in there still.

sounds like set up.

what condition are the pads? if OK start from the begining with pad set up. cleaning the piston walls and calipers will not hurt.

As i said Bleeding is the last thing that should be done and in 99% of the time is not the solution.

ChingfordMarin

The pads are slightly worn but still have a lot of life in them. I will check if the pads move straight away.

What is good to clean the piston walls with?

Thanks guys I shall try tonight and report back.

Anonymous

nicklouse wrote:

As i said Bleeding is the last thing that should be done and in 99% of the time is not the solution.

+1 and another few to this.

Bleeding brakes never actually helped my brakes in the past, is messy, and possibly made things worse. If you think about it, they shouldn't really have much, if any air in there and unless the seals have gone or you've messed about with them they shouldn't get any more air in them.

The first reaction to brake problems is "bleed the brakes!", but I think this is what causes a lot of the problems. That and bike shops recommend it as it earns them some money.

Anyway, when pumping the brakes, is this required all the time or only just initially when going out for a ride? Do you take the wheels off for transport, and if so are the pads retained with any kind of stop?

Reason I ask is often a little knock on the lever when the wheel is out will push the pads in a little and when you get the wheel in (maybe you needed to push the pads back or maybe you are lucky and the disc still fits), the pistons basically need resetting.

Pumping the lever a few times resets the brakes. In my experience. That said, my old Juicys were never very good at doing this, whereas the X0s I have now take a few flicks and they're bang on each time.

386ka

Have you pressed the levers while the bike is upside-down?

Northwind

To be fair though, I agree with the comments on bleeding in general but pumping up like this often is a symptom of a bad bleed.

nicklouse

Northwind wrote:

To be fair though, I agree with the comments on bleeding in general but pumping up like this often is a symptom of a bad bleed.

But it depends on what is happening to the pads and the rotor. Pumping up on its own mean little. Unlike on a car wher there is little or no flex.

Northwind

Aye, definately agree with that, just think it's being ruled out a bit too decisively.

The Rookie

nicklouse wrote:

Unlike on a car wher there is little or no flex.

Try a RWD Escort on wide slicks, the struts bend and you get big pad knock off........also got the same on rally stages on certain types off 'roughness', washboarded gravel seemed worst!

Simon

nicklouse

The Beginner wrote:

nicklouse wrote:

Unlike on a car wher there is little or no flex.

Try a RWD Escort on wide slicks, the struts bend and you get big pad knock off........also got the same on rally stages on certain types off 'roughness', washboarded gravel seemed worst!

Simon

but not during set up and bleed.

and yes been there done that.

The Rookie

Not during static set up and bleed, no!

bobbygloss

386ka wrote:

Have you pressed the levers while the bike is upside-down?

This happens on my Deore brakes, pull the levers while upside down and the brakes go slack, but then turn the bike upright and the levers firm up after a few pulls. Doesn't seem to be a problem in use.

Northwind

Now that one, I bet you 50 scottish pence that it's a bleed issue- doesn't need bled exactly but does need the bubble of air taken out of the reservoir.

bobbygloss

Could be. I've never tried bleeding them, the brakes are about a year old and still seem to work normally. It's the first time I've had discs so maybe I just have low expectations, but they are good enough for me.

ChingfordMarin

So I finally had a look and the brake was filthy and the pistons were returning very slowly. I cleaned it all and they now return quicker but not fully.

Performance is a lot better (Thanks All!) but I am worried that if I replace the pads the piston not fully retracting could mean that there is not enough clearance for the rotor to move. Could the system be overfilled now?

The Rookie

It will only be overfilled if it's been topped up without the pistons being fully back....

Simon

surrpaul

You're don't strictly bleed brakes because air gets in them, condensation builds up in the brake lines and reduces performance. His issue might be that the fluid needs changing, but I suspect it's a caliper issue. Is the wear even on the pads?