How do I know what is wrong with my brakes?

Question

My brakes are not powerful anymore, it takes a few meters when fully pulling my brakes for my bike to come to a stop. Which means that the brakes'pads are touching the wheels but not enough.

So, my question is: how do I know if I need to change the brake pads or give more tension to the cable?

Have you tried the barrel adjuster on your brake cable? It's highly likely it just needs a turn to give you back your brakes — Gordon Copestake, Jul 23 '15 at 09:30
@GordonCopestake - If the levers are bottoming out it likely would take at least two turns on the barrels to fix, and it may be time to tighten the cable where it's clamped by the brake. — Daniel R Hicks, Jul 23 '15 at 12:10
@Burn_E99 I dont want to tighten, as answer showed, it would make no difference. My rubber block has worn out... — Bruno Lubascher, Sep 08 '15 at 10:27

score 4 · Accepted Answer · answered Jul 23 '15 at 09:07

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How thick are the pads? Are these rim brakes or disk brakes? For rim brakes, the block (rubber) will get worn away over time so you should adjust the cable occasionally, but well before the block is so thin that the shoe (the metal backing) starts to scrape on the rim.

For disk brakes it's essentially the same but the pad is thinner and made of harder material. The manufacturers usually give a number how thin the pad can become, something like 0.7 mm.

answered Jul 23 '15 at 09:07

Stephan Matthiesen

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The problem was the the rubber block was so thin that the shoe was scrapping the rim. So, there was no friction, so not stopping. Thanks for answer. I changed my rubber block. – Bruno Lubascher Sep 08 '15 at 10:26

score 2 · Answer 2 · answered Jul 23 '15 at 11:41

2

With fully pulling you mean the lever touches the handlebars? Simply tensioning the cable and checking the pads should be enough.

You should also make sure the cable is properly clamped on the brakes.

answered Jul 23 '15 at 11:41

Michael

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score 2 · Answer 3 · answered Jul 23 '15 at 12:12

There are several things that could be causing the problem (in rough order of likelihood):

As others have pointed out, the shoes (or pads if you have disk brakes) may have worn to the point where they need to be replaced or the brakes need some adjustment.
The brake cable may have stretched or slipped.
Many caliper brake systems have a quick release to create some slack in the cable for changing the wheel. If the release is in the open position that you will have very little braking power from the affected brake (or none in the case of cantilever or center pull brakes). Common locations for the quick release are at the anchor bolt on side pulls, at one end of the straddle cable for cantilever or center pull brakes, or at the brake levers themselves.
Something may be contaminating the rim or disk preventing the pads from developing as much friction as they used to.
It is also possible that a part was damaged in a crash or during handling of the bike. Check that the brakes move freely and return easily when you apply the lever.

How do I know what is wrong with my brakes?

3 Answers3