Bicycle brakes screeching - how do I fix this?

splishsplash

Hi everyone,
I'm not sure where to post this, feel free to move if it's in the wrong place...

I got my son a new bike a week ago, and the brakes have been screeching when he pulls them (front and back). They stop the bike, i.e. they are working, it's just that the noise is really loud. They're not rubbing or anything when they're not being pulled.

What can I do? Is there something really quick and simple that will fix it, or do I have to bring it back to the shop?

Any help would be appreciated

vwjo

I would try rubbing the braking surface with some fine sandpaper? Not sure if it'll work but..... worth a try?

coolagarry

http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3804

About halfway down the page is a paragraph titled

Brake squeal – 2002.03

splishsplash

vwjo wrote: »

I would try rubbing the braking surface with some fine sandpaper? Not sure if it'll work but..... worth a try?

All I could find was some very fine sandpaper - we gave it a go, but they're still screeching... I'll get some slightly rougher paper tomorrow and try again.

Thanks for the tip:beer:

splishsplash

coolagarry wrote: »

http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3804

About halfway down the page is a paragraph titled

Brake squeal – 2002.03

I'm not a bit familiar with bikes really, other than to sit on them and go! This seems to be telling me to toe-in the brakes a bit? I'll have a little search and see if I can find a step-by-step guide and give it a go tomorrow, if the sandpaper doesn't work.

Thank you:T

shown73

Surely roughening the braking surface with sandpaper is defeating the object, since that sort of friction works best on smooth shiny surfaces. Just look at your brake pads/discs, that's why they take a while to bed in. I've had the same thing before on bikes, and sadly, I don't know the answer, except that it seemed to cure itself. Maybe they just need more bedding in.

TimBuckTeeth

I wouldn't advise sanding the wheel rims either.
Try cleaning them with isopropyl alcohol (electronics cleaner) or meths to remove any grease and dirt from manufacturing, don't try white spirit or anything else as it can leave a residue on the braking surfaces.
Otherwise try adjusting the angle of the pads slightly, if after leaving them to wear and bed-in all else fails try a different brand of brake pads.

martindow

As the bike is only a week old I would go back to the seller and get them to have a look. If the brakes need toeing in, this suggests that they have not assembled or checked the bike over thoroughly before selling it to you.

uktyler

The brakes on a bike need to be set up carefully, the front of the block needs to touch the rim before the rest of the block, thus is the 'toe in'. Sanding blocks or rims is something I would not recomend. It is easy to adjust the brakes, loosen the block, and then wiggle it so the front touchs first, and this should solve the problem.

There is a discription and pictures here:
http://www.exchangecycletours.org/V-brake.htm

Look about half way down the page.

splishsplash

Ok, the sanding didn't help, nor did the cleaning .

The shop is thirty miles away and I can bring it back on Wednesday if all else fails - it's just less of a chore if I can do it myself.

Many thanks for the tips and the step by step guide, I will try it later when I'm back at home:cool: .

Idiophreak

TimBuckTeeth wrote: »

I wouldn't advise sanding the wheel rims either..

Don't think anyone's advocating that...I think by braking surface, vwjo was referring to the brake pads themselves.

And I, too, think it will probably sort itself out...the phrase is "squeaky clean" - normally, on the top of the brake pad there's a slightly glossier layer of rubber (or whatever they're made from)...with use, you'll get a bit of dirt involved and the pads will start to wear through this layer. I'd imagine at this point the squeaking should quit - this is why I don't think it's *entirely* counter-intuitive to suggest sanding them down a bit...