Tuesday, April 21, 2009

How-To: Center your caliper

Lets face the facts. Almost all bikes nowadays come with disk brakes whether they be mechanical or hydraulic. One of the more common problems surrounding disks is that they need adjusting every once in a while to get rid of any brake rub. Brake rub is when the rotor contacts the pads while the wheel is spinning freely. As you might have guessed an easy way to test for this is to lift your wheel off the ground and give it a spin. It should make at least a few revolutions without stopping or making any noise. Note: if you have liquid sealant in your tires like Stans it will reduce the amount of revolutions, not to be confused with brake rub :-) Today I am only going to cover how to center hydraulic disk brake calipers. There are many myths and techniques surrounds how to do this. From experience I have found the following method to be by far the fastest and most effective. Keep in mind there is a lot more to disk brakes then just centering them. I'll cover stuff like sticky pistons, lever throw, rotor straightening, and piston centering in other how-to's.

First step is also the most important. Make sure your wheels is centered in the frame or fork!!! There is nothing worse then taking the time to center the caliper and then realising your wheel wasn't straight in the dropouts. It happens to us all. Hold the wheel tight against the dropouts to keep it square while simultaneously tightening the quick release. Or you can do it while the bike is on the ground.

For me, centering calipers has a lot to do with paying very close attention with my eyes and ears. I'm not going to tell you to squeeze the lever and tighten the bolts, or insert business cards yada yada yada. The process is pretty darn simple but requires a light touch. Be patient, it might be hard at first but gets easy quickly the more times you do it. First step, spin your wheel while looking at the gaps between pad and rotor. You should see daylight on each side, that is the cue that you are looking for. From this picture you can see that there is clearance on the right but not the left.
To reposition the caliper start by loosening the caliper bolts. Don't back them way off because usually the caliper is only off center by a little bit. If you loosen the bolts just a bit then the caliper should still be held in place but also be movable by hand.

This is what I mean by movable by hand. The caliper can now be moved to the left or right. Move it one side at a time.

You can see now that there is an even gap on either side of the pads on one side of the caliper.

Snug only the bolt on the side where there is now an even gap.

Now do the other side. Gently push the caliper on the other side to even up the gap between rotor and pads. Since you only snugged the bolt on the side you already adjusted and didn't tighten it down completely then you will still be able to move the caliper without messing up the proper gap you already have.

Now snug this bolt down. At this point your gaps should be pretty good and both bolts are snugged. Spin the wheel to see if there is any rub or noise. If there is then observe the spinning rotor moving through the caliper. If it rubs for only one portion of the rotation then you have a warped rotor. If it's not super warped then you should be able to readjust the caliper a little to compensate for this and still have no rub. If this isn't possible then you need to straighten your rotor. I'll cover this later :-)

Now tighten down the bolts to your recommended torque specs. Sometimes the tightening of the bolts can shift the caliper a little. Spin the wheel again when you are all done to make sure there is still no rub.

Note: I believe Avid's are the only caliper that are adjustable on 3 dimensions. This means they come with washers that allow you to rock the caliper. This is so that you can make sure the pads are completely square to the rotor in all dimensions. This makes adjustments a little more tricky but the technique stays the same. Adjust while looking for the gaps and snug the bolts when you feel you are getting close.
That's all there is to it. Practice makes perfect. Enjoy your drag free brakes and increased velocity!

Check this out for the super pro method of installing new brake pads and servicing a caliper.


  1. this was very helpful


  2. Very nice tips - thx! :)

  3. avid is shity, formula brakes is made in italy not asia like most products from sram, i like sram, but brakes is shity.