Adjusting brakes

Schoie81

Hi guys,

Just replaced/upgraded the 'factory standard' brake blocks that came on my Giant Defy. However, the rear blocks don't seem to sit parallel with the rims on the bike. I'd say the back of the block is probably 2-3mm closer to the rim than the front - ie. if I pull the lever until the block makes contact with the rim, the front of the block is still about 2mm away from the rim. Is this normal? If not, what can I do about it? I can't see any obvious way of adjusting the angle of the blocks? Do I just wait until the blocks wear down (I assume the rear of the block will wear down quicker than the front until the surface is level with the rim...)

The blocks on the front wheel seem fine - certainly nowhere near as much of a difference between the front and back of the blocks...?

keef66

There's usually some adjustment to be had by loosening the mounting bolts and aligning the blocks with the rim while tightening again. Some have a couple of dished washers in there to facilitate this.

Failing that, the old-skool way was to gently bend the caliper arms using a big adjustable spanner :shock:

Schoie81

keef66 wrote:

There's usually some adjustment to be had by loosening the mounting bolts and aligning the blocks with the rim while tightening again. Some have a couple of dished washers in there to facilitate this.

Failing that, the old-skool way was to gently bend the caliper arms using a big adjustable spanner :shock:

Thanks keef - the second option does look like the only one... but I'll have a closer look!

Manc33

Hold the brake caliper on the rim with some sort of clamp (another thing that needs inventing ) thus making the pads "adjust to the rim" then tighten the cable, then release the caliper. Don't forget to do all that with the barrel adjuster turned about half way out so it can be screwed in slightly to release the brake pad.

964cup

Don't try to bend the calipers. The toe-in of the blocks will be adjustable; there's a spherical washer between the brake carrier and the arm of the caliper. Just loosen the allen bolt, line the block up and then retighten. It can be helpful to hold the brake closed (have someone pull the lever) once you've got the block lined up, both to keep it in place and to be sure it's in the right place on the rim when the brakes are applied.

Manc33

It won't necessarily have a curved washer. My MTB brakes have them but not my road bike.

Schoie81

So how should the blocks line up with the rim? Should they be parallel, or should, as my own logic suggests (but couldn't be completely and utterly wrong) the front of the block make contact with the rim slightly before the rest of the pad?

Manc33

Schoie81 wrote:

So how should the blocks line up with the rim? Should they be parallel, or should, as my own logic suggests (but couldn't be completely and utterly wrong) the front of the block make contact with the rim slightly before the rest of the pad?

No it shouldn't.

Wait I got confused before, all you've got to do is loosen the brake pads, pull the brake, tighten the pads, but when you get it tighter you've got to tighten it up without the brake pad turning.

If you keep the caliper pressed on the rim, then tighten the brake blocks, but it is still touching at the front after that, I don't know.

Its true that it will just wear straight eventually, but you shouldn't have it misaligned to start with.

rafletcher

Manc33 wrote:

Hold the brake caliper on the rim with some sort of clamp (another thing that needs inventing )

It's called a "third hand tool" and has been around for donkeys years.

https://www.google.co.uk/search?sourcei ... 1ffFEK7Ygg

Schoie81

Manc33 wrote:

Schoie81 wrote:

So how should the blocks line up with the rim? Should they be parallel, or should, as my own logic suggests (but couldn't be completely and utterly wrong) the front of the block make contact with the rim slightly before the rest of the pad?

No it shouldn't.

Wait I got confused before, all you've got to do is loosen the brake pads, pull the brake, tighten the pads, but when you get it tighter you've got to tighten it up without the brake pad turning.

If you keep the caliper pressed on the rim, then tighten the brake blocks, but it is still touching at the front after that, I don't know.

Its true that it will just wear straight eventually, but you shouldn't have it misaligned to start with.

Thanks! Had a quick look just and I can see how the angle can be set now. Was too excited about having brakes that actually do something rather than just make a noise and didn't pay enough attention to what I was doing!! I made sure they were on the rim and not near the tyre sidewall, but didn't see that you could set the angle too. Will get them sorted before I ride it again! Thanks for talking it through with me!!

kajjal

To stop squealing and allow better braking a slight toe in is a good idea as it means the brakes are dragged onto the rim by the motion of the wheel. Just fold a small piece of paper, when you pull the brakes on put it at the very back of the block and the tighten. It is only a small difference and more noticeable in the wet or if you previously had the front further away than the back.

Schoie81

Kajjal wrote:

To stop squealing and allow better braking a slight toe in is a good idea as it means the brakes are dragged onto the rim by the motion of the wheel. Just fold a small piece of paper, when you pull the brakes on put it at the very back of the block and the tighten. It is only a small difference and more noticeable in the wet or if you previously had the front further away than the back.

That's what I meant earlier by 'my logic' - it would seem to my mind to make sense if the front made contact very slightly before the rear of the block. Thank you!