Brakes are one of the most crucial parts of a mountain bike. Helping slow down and stop the bike whenever you need to, brakes help you avoid accidents. However, for brakes to be effective, they need to be in good condition, clean, and well adjusted.
Over time – and after putting numerous miles on the road – disc brakes do lose their effectiveness. This leads to less efficient braking, longer response times, and less bike control. The only way to eliminate these issues is by adjusting bike disc brakes. In this guide, we will take you through bicycle disc brakes maintenance.
A Detailed Guide on Checking and Adjusting Bike Disc Brakes
Understanding Disc Brake Assemblies
Before we show you how to check and adjust your disc brakes, we need to ensure that you understand the brake components. Disc brake assemblies include the brake pads, brake levers, and the brake calipers.
To stop your bike, the brakes use the calipers mounted to the frame in the back and fork in the front, and the discs (rotors) that are mounted to the bicycle wheel hub. When you squeeze the brake levers on your bike handlebar, the pads inside the brake calipers squeeze the discs to slow your wheels down.
The brake components do not always work as the rider would want them to. Sometimes, the assemblies could be installed incorrectly or they may get jarred out of the ideal position as a result of accidents or aggressive riding. Checking and adjusting bike disc brakes helps you ensure that the components are moving freely, perfectly positioned and that all the bolts are snug.
Adjusting Mis-Aligned Brake Assemblies
Checking the position of the brake assemblies involves visually inspecting both the rear and front calipers. You need to make sure that each rotor is centered in between the brake pads. Every time you engage the disc brake, each pad should make full contact with the rotor.
Mis-aligned or off-center disc brakes cause one side of the brakes to make full contact with your rotor before the other side does. This results in both noise and poor braking power.
In many cases, readjustments involve loosening the bolts and then moving the brake caliper slightly from side to side to position it properly. Some brake calipers will require that you remove or add shims to center the brake calipers over the discs.
Maintaining the Brake Pads
Over time, brake pads do wear down due to normal use. This often leads to longer brake response times and you will need more effort to engage the brakes. Part of bicycle disc brakes maintenance is ensuring that the pads are in good shape – this facilitates effective braking.
Check to see if the brake pads are significantly worn or glazed. To check your brake pads, you will have to remove the bike wheel and look into space where the rotor spins – our guide on how to change a bike tire can help you with removing the wheel.
If the pads are glazed, remove them from the brake calipers and scuff them lightly using a piece of sandpaper placed on a flat surface. If your pads are less than 3 millimeters thick, including the metal holder, you will have to replace them.
Pad contamination is one of the leading causes of squealing disc brakes. The brake pads can be ruined by oil from your skin and the tiniest amount of soil. For this reason, whenever you handle the brake pads, minimize contact between them and your bare skin.
If you touch the pads, use rubbing alcohol – or a product designed for cleaning brake pads – to clean them. After cleaning the bike brake pads, use sandpaper to rough them lightly.
Fixing the Brake Rotors
Check the brake rotors (discs) for debris and dirt. Also, look to ensure that the rotors on your hardtail mountain bike are straight and that they do not rub on your brake pads. If your rotors are dirty, use rubbing alcohol to clean them. Next, lightly rough them using sandpaper.
While checking the rotors, confirm that the bolts that attach the rotors to the MTB wheels are snug. Loose parts will vibrate and make noise while braking.
Checking and Fixing the Brake Levers
Part of adjusting bike disc brakes involves ensuring that the brake levers are functioning properly. The brake levers can get gummed up with dirt and grime over time. They can also slip out of position on the road bike handlebar. If your bike uses hydraulic disc brakes, you will need to check for signs of leaking brake oil near the brake levers.
To check the brake levers, you will simply need to squeeze them. When they are fully engaged, there should be approximately a 1-inch space between the handlebar and the inside edge of each lever.
The brakes should be able to hold solidly against the rider’s leaning weight. The levers should be firm on the handlebar – test each lever separately by pushing it laterally, down, and up – and they should move smoothly when a rider squeezes them, without squeaking or jerking.
Important: If you are working on hydraulic disc brakes, avoid squeezing the levers when the wheel is removed from the bike’s frame or fork. Doing so can cause the self-adjusting brake pads to clamp very tightly and you may find it extremely hard to separate them.
If you determine that the brake levers are not responding perfectly, you can use the following tips in your bicycle disc brakes maintenance routine:
Clean and Lubricate the Brake Levers
Apply a very small amount of lubricating oil to the pivot zones while squeezing the brake levers open and closed. If your bike uses mechanical disc brakes, wipe down, and then lightly lubricate the cables – this should be done every few months or whenever you seen any signs of rust and/or grime on the visible surfaces. When lubricating the brakes, be extra careful to avoid getting any lubricant on the rotors or brake pads.
Bleed the Brakes
If your bike has hydraulic brakes and the brake levers feel spongy every time you squeeze them, your braking system might have some air bubbles. In such a case, bleeding the brakes is the ideal solution – our guide on how to bleed Shimano brakes should help you out. Bleeding will purge your hydraulic hoses of any bubbles.
Reposition the Brake Pads
If your bike has mechanical disc brakes, the brake pads may not be close enough to your rotors. To reposition the pads, turn the adjustment dials located on the brake calipers to bring the brake pads closer to the rotors. The ideal distance between the brake pads and rotor will depend on the brake style – you will, therefore, need to consult the instruction manual that came with the brakes.
Note: Hydraulic disc brakes come with self-adjusting brake pads. Hence, you won’t find adjustment dials on the hydraulic calipers.
Inspect the Housings, Cables, and Brake Hoses
For hydraulic disc brakes, check for leaks on the fittings and hydraulic hoses. The leaks can sometimes be tough to detect. However, dirt often builds up where there are leaks – this is one of the signs to watch out for. If you can’t detect any leaks, taking the bike to a repair shop might be a good idea.
Just like rim brakes, mechanical disc brakes use cables and housings. The cables can fray, weaken, or rust over time. When this happens, the resulting extra slack can cause a slower response when the rider squeezes the levers.
The flexible housings that protect the brake cables can fray, clog up, break, or corrode over time. Fixing the housings ensures that the cables are moving freely through the cable housings. If the housings do have issues, taking the bike to a repair shop might be a good idea.
Q: Do Disc Brakes Need Adjusting?
Disc brakes do require adjusting. The disc brake assemblies can get jarred out of their ideal position as a result of aggressive biking riding, crashes, or accidents. Adjusting the brakes on your road bike helps you restore them to proper working condition.
Q: How Do You Adjust Rear Disc Brakes?
To adjust the rear brakes on your commuter bike, you need to ensure that the rotors are positioned perfectly between the brake pads. If the brakes are miss-aligned or off-center, loosen the bolts and then move the caliper side to side to position it properly.
Q: How Do You Adjust Hydraulic Disc Brakes on A Bike?
If you have hydraulic MTB brakes installed on your bike, adjusting them will involve fixing the brake levers, aligning the rotors properly, replacing worn brake pads, and bleeding the brakes to remove air bubbles. In this guide, we have explained how to do this in detail.
Globo Surf Overview
The majority of modern mountain bikes come equipped with disc brakes, and more and more commuter and aluminum road bikes now feature these brakes. This means that understanding the process of adjusting bike disc brakes is extremely important.
This guide takes you through bicycle disc brakes maintenance. Through regular checks and adjustments, your disc brakes should maintain perfect braking power.