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This is probably a really basic question but I'm confused by the whole brake mechanism so...

My left (front wheel) brake has to be pulled in really far before it actually starts to brake (I guess before the brake pads touch the wheel). What do I do to tighten it up? (diagrams would really help, I think)

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What brand and model of brakes do you have? –  Dana the Sane Sep 11 '10 at 0:20
    
Dana is correct, but a picture of your brakes and levers would also do. –  Neil Fein Sep 11 '10 at 2:19

4 Answers 4

up vote 11 down vote accepted

There are two basic adjustments that apply to all types of rim brakes (v-brakes, cantilevers, calipers):

Tension: The cable tension from the brake lever to the brakes adjusts how responsive your brakes feel. Tighten it up and both brake pads will engage sooner and the braking action will be harder. Loosen it up and braking will feel spongy and you may not get enough power. Normally you want to add tension; removing tension is only done when you put on fresh pads or if you set the tension too tight. Adding tension periodically is important since your pads wear down over time and the cable stretches a bit too.

The easiest way to adjust the tension is to use a barrel adjuster: they're usually on the brake lever or the brake or both if you're lucky. Add tension by turning the adjuster counter-clockwise (looking at it from the side where the cable housing goes in).

But whenever you adjust tension, you need to fix...

Balance: This controls how far each pad is from the rim. Adding tension will pull both pads closer to the rim, but usually one will move more than the other. So by adjusting balance you can move the closer one further away and the other pad will do the opposite. You want to balance the pads so that they're about the same distance from the rim and engage at about the same time. If it's skewed (like your brakes) then you won't get as much braking power.

For v-brakes and canti's there's a spring inside each brake arm. You can adjust the spring force by turning a small set screw on the side of the brake arm. Screwing it in (clockwise) will pull the arm away from the rim (which pulls the other one closer). It's best to adjust the two arms together: screw in the closer arm first by half a turn to start, and screw out the other one by the same amount. Check the balance and then repeat as necessary.

For caliper brakes (road bikes) there's normally just one set screw to adjust. Turn it to see which way the brakes move.

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Most V-Brakes have a little screw at the base of each 'arm' that adjusts the pre-load. To move the brake pad closer to the rim, I believe that you need to loosen the screw.

If that doesn't completely fix the problem, you might have to apply some oil to where the arm pivots.

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I would add, be careful not to get any oil on the brake pads or the rim of the wheel. (It seems obvious that this would be a terrible idea, but I was once advised to put oil on the rim to fix a squeaky brake -- no, really!) –  Neil Fein Sep 14 '10 at 3:12
    
At least for the braking surface on the rims, you can clean that with alcohol or brake cleaner. I guess the pads would be ruined if the oil soaked in though. –  Dana the Sane Sep 14 '10 at 12:42
    
I'd note that this adjustment is only really useful for moving one pad closer while moving the other further away. You need to adjust the brake cable to move both pads closer or further away. –  deemar Sep 21 '10 at 9:57

You can probably used the barrel adjuster near the brake lever itself to take up some slack in the cable. While looking from the cable towards the brake lever, turn the barrel adjuster counter-clockwise (to the left) a turn or so at a time until the distance of pull on the brake lever is reasonable.

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@darkcanuck has the right idea with his explanation.

Adjusting brakes is easiest if you've got a friend to help you or a "third-hand" tool that you can use to hold the brakes all the way in while you adjust the cable.

The basic process that I'd follow for setting up brakes is:

  • Check that the brake pads don't need replacing.
  • Get your friend or your "third-hand" tool to hold the brake closed so that both brakes touch the rim.
  • Wind the barrel adjuster on your brake levers in so that it is as far in as it can go, then wind it back out a turn.
  • Find the bolt that holds the end of the cable to the brake mechanism. Loosen this bolt.
  • Pull the end of the brake cable as tight as you can and while holding this tension tighten the bolt that holds the end of the brake cable to the brake mechanism.
  • Your friend / tool can now be removed from the brakes.
  • Wind the barrel adjuster on the brake lever all the way in. This should let the brakes out a little bit so they clear the rim.
  • Check the balance of the brakes (see @darkcanuck's post). If one brake pad is rubbing adjust the balance so that both brake pads are clear of the rim.

If your rim has a few wobbles to it, you may need to wind the barrel adjuster out a bit more when you set the tension.

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A cable tie can make a good “third hand” for this. –  Ian Oct 18 '10 at 9:25

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