Today we will tackle the Pandora’s Box that is brake adjustments. Since there are several brake types in use out there we will bring our focus down to the typical mountain bike brake types: Cantilevers and disc brakes. Cantilevers include “V” or linear pull brakes, traditional cantilevers, and the odd “U” brake. There are others out there, but I find that these are the three most commonly seen types. Let’s take a closer look………

An example of a typical cantilever brake arm and shoe.

Cantilever brakes have been used on mountain bikes since the early days, and while being somewhat out of favor now, are still commonly seen. Note that there is typically two arms to a set, one on each side of the wheel. There is typically a “straddle wire” or yoke that forms two sides of a triangle that meet directly above the wheel. If the cables/yoke look fine, then generally an adjustment will either entail accounting for brake pad wear, and/or adjusting the shoe itself.

If you are simply accounting for brake pad wear, you might get away with a simple loosening of the anchor bolt on top of one of the cantilever arms and pulling through a little bit more cable. Retighten the anchor bolt and check for proper shoe alignment. If the shoe isn’t contacting the tire, hitting the rim at a weird angle, or isn’t making noise when applied on a test ride, you are done here. But……..it almost is never that easy!

Loosen that nut at your own risk!

Cantilever brakes have been known to give budding bicycle mechanics fits, so if you are short on patience, you may want to pass up adjusting one of these. If you are feeling lucky, proceed with caution! In the photo above you can see two important things. First of all, there is screw sticking out of the plastic spring retainer. This screw “balances” the arms by way of adjusting the spring tension either on one side only, as this Shimano canti does, or by using a screw or Allen head adjuster at the base of each arm. Usually turning the adjuster clockwise adds tension, forcing that cantilever off the rim further. Counter-clockwise adjustments do the opposite. You want to attain equi-distance from the rim for both brake pads if at all possible. That’s easy enough. (If the pad on one side is butted up against the canti arm and the opposite pad is sticking out from the arm on the pad’s post, you’ll need to use the fixing nut on the back side of the arm to account for that and get the pads set equally. See below.)

Now you will also see a nut in the above photo. That one unleashes all the ways you can adjust the brake shoe itself. In and out, vertically, and axially in three planes. Yup, it’s a multi-functional adjustment, and not always very easy. Look at the top picture again. Notice how the shoe sits against the rim along the entire length of the shoe. Two things need adjusting there. One: The spring adjuster screw needs to be turned to help this pad off the rim. (Check the other side first, obviously. If it is way off the rim, the adjustment will be the correct one.) Secondly, the “toe” of the brake shoe is off, and needs reset. This is most common with worn shoes.

So you will need to loosen that nut, the one that has all the functions, but here’s the trick: Don’t loosen it all the way! Just loosen it enough to move the shoe. Go back to the top photo and notice where the shaft of the shoe passes throgh the cylindrical pad holder. See that the end is a hex shaped Allen key recepticle? A five millimeter wrench will fit this one, and you want to line up the long end of a “L” bend Allen key with the post sticking out of the pad. Now this will be used as leverage to move the pad while the nut on the back side of the arm is loosened ever so slightly. The brake shoe should strike the front or leading edge of the pad first. (Thus the term “toe in”.) You will want no more than two millimeters of space between the back end of the pad and the rim when the leading edge strikes the rim, so only a slight move of the pad is usually necessary. Once you get the pad to move where you want it to, lock down the nut while holding the pad position with the Allen key. This may take several tries before a satisfactory result occurs. If you loosen the nut too much, you’ll have a handfull, so be careful to go a little at a time here.

If you get in over your head, no worries! Just head on down to the local bike shop, or hit up a buddy that is more proficient at it than you. It’s a good skill to learn though, so don’t give up.

Next time: Linear Pull brake adjustments and a quick look at a “U” brake.