Cable Disc brakes help!

[mxwill63]

Hi i have a giant brass (really shit i know) and the cable brakes on it have been mucking up

My problem is that when i adjust the brake tension by moving the cable slightly more through the thigy (sorry really hard to explain) the brake will then have enough tension that i can brake just using one finger (instead of having to use whole hand)

The problem then being that when my brake tension feels perfect, the pads then start rubbing against the disc, making it hard to get one rotation out of a slight turn of the wheel

So it goes in a huge circle that i take off the tension so that the wheel spins freely, but then no brake lever tension, so going in such a big circle is really pissing me off

So i was just wondering if you had any suggestions to help me or whether its back to the bike shop

Cheers, Will

 

[timedward]

There should be a pad adjust screw on the caliper of the brake. This will move one of the pads in closer to the disk to give you a more firm feel at the lever. Hence you can keep the cable where it was originally...

 

[mxwill63]

There should be a pad adjust screw on the caliper of the brake. This will move one of the pads in closer to the disk to give you a more firm feel at the lever. Hence you can keep the cable where it was originally...

Cheers i had a look at that, but ill have to give it a go tommorow

 

[smittyDH]

depending on how hard you have been on your brakes either as was said before the brake pads should either be moved in or you need new brake pads i advise moving away from cable disc brakes into hydraulic they are alot more efficent and have alot better adjustments on them

 

[tomacropod]

The average cable disc brake has brake lever throw adjustment, spring tension adjustment, inboard pad adjustment, outboard pad adjustment and lever reach adjustment.

Find me a hydro disc brake with this many adjustments.

- Joel

 

[smittyDH]

they may have many adjustments but notice how i said efficient not MORE adjustments all together

 

[tomacropod]

they may have many adjustments but notice how i said efficient not MORE adjustments all together

everything, no matter how unpopular, needs a devil's advocate. Rotorburn is a particularly important place for such a view.

to the OP, your cable disc brake can be made to work very well. It comes down to a few things:

Minimise resistance. This basically comes down to efficient cabling. If your existing cabling is shoddy, worn out, has dirt or grit in it, or is corroded (rusted), replace it with quality cabling. The normal Shimano cabling most shops have rolls of is good. If you think your cabling is OK, run some light oil along the inner cables and it should be good.

Make sure your rotor is straight. It can be straightened in many ways, but none of them require an engineering degree.

Only one pad is actuated with cable brakes - the outboard pad. As such, the brake relies on the deflection (bending) of the rotor in order to contact the inboard pad. As such, the brake should be set up to minimise deflection and to maximise pad contact area with the rotor. This means setting the brake up so that the inboard pad rests as close to the rotor as possible without actually dragging on it while riding. This will give a firmer feel when the outboard pad pushes the rotor across to the inboard pad and squeezes it, and more power.

Make sure the caliper is aligned, that the pads run along parallel to the rotor. You can usually see the gap between the pads and the rotor, make sure the gap is the same at the front and back of the caliper. You can also judge this by pulling the lever and seeing if the rotor twists upon contact of the pads. If it does, realign the caliper until it doesn't twist.

- Joel

 

[Anakist]

Only one pad is actuated with cable brakes - the outboard pad. As such, the brake relies on the deflection (bending) of the rotor in order to contact the inboard pad. As such, the brake should be set up to minimise deflection and to maximise pad contact area with the rotor. This means setting the brake up so that the inboard pad rests as close to the rotor as possible without actually dragging on it while riding. This will give a firmer feel when the outboard pad pushes the rotor across to the inboard pad and squeezes it, and more power.

The BB7 is designed to have twice as big a gap on the inboard pad as the outboard pad. I have a Clarkes CMD-6 and if I set it same as the BB7 it is ok, but if I set it so the inboard pad is close I get squealing.

I am struggling to get decent stopping power out of it with no squealing. Will have to go recheck parallel though I think.

James

 

[tomacropod]

The BB7 is designed to have twice as big a gap on the inboard pad as the outboard pad. I have a Clarkes CMD-6 and if I set it same as the BB7 it is ok, but if I set it so the inboard pad is close I get squealing.

I am struggling to get decent stopping power out of it with no squealing. Will have to go recheck parallel though I think.

James

I'm not sure how the BB7 is designed, I suspect Avid isn't too fussed how people set them up. Running the inboard pad close to the rotor minimises the angle at which the rotor hits the pad and the amount of lever force required to move the rotor over that amount. It increases power and gives a better lever feel. I've used BB7s extensively and have always set them up this way - in my experience, it works the best.

- Joel

 

[beno]

cable disks can also be improved heaps by using compessionless brake housing, or using gear housing in place of the std spiral squishy brake outer. This gives you more power, a firmer lever feel, as well as making them easier to adjust.