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Adjusting Mountain Bike Disc Brakes – How To



February 25, 2021

disc brake on a mountain bike

All-weather control and cycling confidence have been revolutionized by the introduction of disc brakes on road bikes, but they require good synchronization to operate properly. Disc brakes provide excellent modulation of the brakes and plenty of power regardless of the weather. They also encourage bigger tires than rim brakes to be used even if the tire is a little twisted, they don't care.

However, the quiet, predictable, rub-free function relies on the clearance of fractions of mm between pad and rotor. There could also be some reasons if your brakes have started scratching, so we have added a menu to help check all the potential complications as well as change the callipers themselves.

It’s no longer odd to see disc-brake bikes on a trip—from hardcore roadie world-championship riding grinds, to the weekly store ride, to the townie bar crawl—the brakes that were once just a feature on mountain bikes have become the modern norm. Heck, even the purists at BICYCLING who vehemently opposed discs on artistic principle have acknowledged their excellent stopping power, exceptional speed control, and better all-weather efficiency on all styles of bikes.

Types of Disc Brakes for Bikes

There are two main types of disc brakes: electric, which operates with cables (just like rim brakes), and hydraulic, which in a fully enclosed line substitutes the cables with hydraulic fluid. See here how to bleed bike brakes.

 The friction causes the fluid to pass towards the calliper while you are braking, pressing the pads against the disc. You are definitely going to end up with automatic braking if you are interested in buying a disc brake-equipped bike for less than $1,000.

 You can pay less and still own a bike with stable, all-weather stopping power with this lower-cost alternative.

Some riders prefer cable-activated disc brakes, except for the price, since they are simpler to operate on at home and compatible with most mechanical brake levers. But there are more bikes available with hydraulic disc braking. It is normally more difficult for the home mechanic to sustain this pricier alternative.

Tools Needed

Depending on the brakes' locking bolts, you will need a 5mm Allen key or Torx T25 key.

For resetting the brake cylinders, a wide screwdriver, wide tyre lever or equivalent flat lever may be effective.

To straighten a bent rotor, you will need a slotted rotor straightening tool or a large, clean, adjustable spanner.

Inspect the calliper

mtb brake adjustment

Next, ensure that the axles are tight and that the wheels in the frame/fork do not wobble. Now, pull the brakes on either side of the rotor while looking down at the pads.

At the same point, they can all transfer the same number. With a flat screwdriver, tyre lever or special piston tool, if only one pad moves, you need to pop the wheel out and force the pistons back into the calliper.

Ensure the rotor is secured

If the brake works properly, by testing for wobble when it passes between the pads, verify that the rotor is smooth. Using a rotor straightening tool if you have one or, if you don't, a clean flexible spanner if you need to straighten it.

And if you don't want to bend it in the opposite way, just flex the rotor very softly and steadily.

 If you're unable to see the rotor over a light backdrop between the tires, position the bike. Even a sheet of white paper will do the same on the surface. Be sure that the rotor is firmly secured to the hub and the rub will obviously be triggered if the rotor shifts slightly.

Centralize the calliper

bake brake adjustment on a mountain bike

In most situations, the trouble would come from the minor change of the brake or from moving wheels to one with a somewhat different location of the disc. You need to gently remove the repair bolts to re-align the brakes so that you can just sideways move the calliper. Via the calliper, post-mount brakes are bolted.

 Flat-mount brakes are bolted from the frame's underside and often from the fork's far side as well. By pushing the lever to clamp the calliper onto the rotor, you will sometimes tighten the brake. And, alternately, you softly retighten each bolt and, theoretically, the brake is properly balanced and you're ready to fly. Sadly, this does not work about as well as most 'how to' manuals suggest it does, so be prepared to manually line things up.

Manually centre the calliper

Manually aligning the brake is just a case of turning the calliper fractionally sideways until when you turn the hammer, there is a consistently noticeable distance between the pad and the rotor Again, making minor changes easier to get the bolts at a tightness where you need to push relatively tightly to move them.

 A major aid to gauge a healthy brake position is also to use a light backdrop. Don't be disappointed if you have to make some minor repositions and modifications to keep the rotor running clean.

Looking from above, as well as being equally spaced, make sure the calliper is perpendicular to the rotor as well as looking down from the front or back at the brake. As long as the frame and fork are correctly balanced, this should not be a concern with flat-mount braking. Some post-mount brakes, however, use pairs of concave and convex washers, and these may shift sideways slightly. Again, to get the rotor running clean through the brake is just a case of tiny adjustments.

Tighten the calliper

Tighten the fixing bolts with small, alternating turns on each one until you are satisfied with the change, so that the tightening torque does not move the calliper out of alignment. Now, a few times, squeeze the brakes hard and then turn the wheel to verify if all is running smoothly and believe you're now able to fly.

 Tweak, if not secured, then retighten until it is. Before and after each ride, always check the other brake at the same time and make a fast spin of the wheel part of your daily ride routine as even a minor scuff can be very irritating while riding, especially in wet and/or gritty environments.

cyycling store

About the author 

Beastie Bikes Pete

Hi I'm Pete. I'm a passionate mountain biker in Australia. I enjoy writing about biking as much as doing it......almost!

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