The brake of a bike is not only there to stop you, but also for control and, funnily enough, speed. All of which are integral when riding off-road.
A brake that provides an effective modulation of power is what you should be looking at. The lever pulls and releases should feel smooth and in control to boost the confidence you have on your riding. The components should also compliment the type of riding you do. Brakes that provide you with great efficiency and stopping power even on the most technical of tracks, should all be within the comfort of your reach.
Disc brakes provide just that and thus are a staple in the mountain biking scene. Its many components are catered toward power and the control of that power. The two major components that primarily affect these are:
- The Rotors
- The Braking Pad
Buying Brakes for your Mountain Bike
But before we dive in further on what to look for on a good MTB disc brake, let’s get this small question out of the way…
Why Not Rim Brakes?
On the same playing field, rim brakes do not differ that much from disc brakes in terms of performance. But we are not in one. Our focus is on general mountain biking conditions; and as such, there are certain aspects of the rim brakes that make it a slightly worse choice for this biking discipline:
- Rim brakes perform very poorly in wet and muddy conditions. They have no mud clearance, meaning mud will accumulate around the brakes rendering them virtually useless.
- Rim brakes can wear through the rim of the wheel over time. More braking is involved in mountain biking, which means more wearing. Wheels are expensive, changing them regularly is something you should avoid.
- Most MTB bike frames are built with disc brake mounts nowadays. Cyclists and manufacturers have caught up with the added benefits that disc brakes provide for mountain biking.
However, you can still find rim brakes on entry to some mid-level bikes. But high-end bikes will always have disc brakes.
A Deeper Look Into Disc Brakes
Disc brakes are substantially more powerful than rim brakes. Thanks to the presence of rotors, the brake pads can engage on a completely separate surface that is specifically designed to provide greater stopping power.
Greater Control or Modulation
The brake engagement is instantaneous. This makes every pull of the lever highly responsive giving you the feeling of greater control. Thanks to its quick responses, tacking more technical tracks are that much easier. This can also directly translate to riding confidence.
Since the braking surface is separate from the wheels, the system becomes naturally more reliable in almost all weather conditions. Not only does this mean better performance but also lower maintenance and in turn lower costs.
Brake Features to Consider
1. Mounting Systems
Unfortunately, you can’t just buy a disc brake and slap it on your bike. The mount of disc brakes on your bike’s frame can vary. This mount size is measured as the distance between the centers of the mounting holes in millimeters. There are two types:
- IS mounts: 51mm
- Post mounts: 74mm
It is very important to have the correct type of mounting system to the disc brake you want to purchase.
If, by chance, the brake that you chose does not match the mounting system of your bike, then you may have to invest in a mount adaptor to make things work.
Rotors are what sets the disc brakes apart from the traditional rim brakes, and is also its namesake. These are strong and light discs of metal attached to either front, rear or both wheels of the bike.
When you pull the lever brakes, the tension is transferred through the brake line and on to the calipers. Here, the calipers squeeze the brake pads against the rotor to produce friction which results in braking.
There are two aspects of rotors that you should be aware of when purchasing a disc braking system:
Rotors come in multiple sizes: 140mm, 160mm, 170mm, 180mm and 200mm.
Larger rotors will have greater mechanical advantages which directly translates to more braking power.
Bigger rotors also have a larger surface area, allowing it to dissipate heat more effectively.
However, larger rotors will add extra weight to the entire system.
The build of the rotor also plays an important part to the overall performance of the brakes.
Usually, rotors are made of a single type of metal, generally stainless steel.
Newer models take the construction a step further by heat treating two different metals, which has a steel braking surface installed onto an aluminum central carrier. This can help reduce the weight of the rotor significantly.
Many premium and competition ready rotors also have aluminum fins to further help dissipate heat.
The added features will of course have added costs.
3. Brake Pads
Can you even think about brakes without the brake pads?
Don’t think so.
Brake pads are what completes the entire system of braking. They go on to the calipers and squeeze against the rotors to produce friction.
But an important thing to note: the shape and size of the brake pads must fit your calipers. The pads won’t matter much if it doesn’t fit the calipers in the first place. So make sure to get the correct pads for your brakes. Get a few spares beforehand, just in case.
With that out of the way, let’s get into the meat of the brake pads, or should I say, compounds.
In general, there are three types of pad compounds out there:
1. Metallic or Sintered
+ Great power. Thanks to it being made of a metal compound with copper shaving, it gives out a lot of friction against other metal braking surfaces. More friction equates to more stopping power.
+ Long lasting. Since it’s metal, chances of these pads wearing out is that much lower.
+ Performs best in messy and rough situations. The weather and environment has nothing on these pads. Be it winter, rain or mud, whatever elements are thrown at it, it can take.
+ They don’t ‘glaze’ over. Metallic pads have higher resistance so they don’t glaze
Note: Glazing: Too much heat can smoothen the pads. Ruins the texture/surface.
– Louder. Metal pads against metal rotors, you do the math.
– Harder on the disc. These pads can wear out the discs over longer periods of time.
– Transfers more heat to the rotors.
2. Organic or Resin
+ Common brake pads. Carbon, Kevlar, rubber and glass, all of it mish mashed together. And very cheap too.
+ The material is soft which allows for great modulation.
+ Less abrasive. Not very hard wearing on your discs.
+ Works great in the cold weather. No preheat required like the metallic pads.
– Initial bite is very good, but not as powerful as the metallic.
– They can glaze over on longer descents.
A middle ground to both metallic and organic brake pads. Offers some of the benefits of both but also some of the drawbacks as well.
- Not as noisy as the metallic pads
- It can glaze over on longer descents, but not as fast as resin pads.
- Has a lot of variety. Different manufacturers have their own take, so it is best to try out a variety until you find the perfect one for yourself.
Being able to comfortably reach your levers is very crucial to your overall braking experience and performance. Having the option to adjust the spacing between your hand and lever is a must, especially if your hands are of a smaller nature.
Bite Point Adjustment
Some brakes allow you to adjust the position of the pads. While it does not bring the pads closer to the rotor, it does however make you feel like it did. This adjustment is unique to each manufacturer: Shimano has its Freestroke and SRAM has its Contact Point Adjustment.
Mechanical or Hydraulic?
There are two types of braking mechanisms available for the disc brake: Mechanical or Hydraulic.
Each has their own merits and disadvantages. From a general perspective, the difference is how the tension is transferred from the lever to the brakes which impacts the overall performance of the brakes.
Hydraulic disc brakes do stand above in performance when compared to its mechanical counterpart, but so does its cost and complexity.
Be sure to read our in-depth breakdown of Mechanical and Hydraulic Disc Brakes
Frequently Asked Questions
Q1) What size of brake rotors do I need for my MTB?
Ans.: With the options of rotors sizes available, it can be confusing to choose the perfect rotor. It really boils down to the type of riding you do.
- For descents and technical tracks you will need more power, meaning larger rotors.
- If you are a heavy set person then more power is warranted, meaning larger rotors.
- For climbing or weight optimization, you should consider smaller rotors.
At the end of the day, rotor size will only see slight improvements to your overall performance, so it is best to stick to the size that you feel most comfortable in.
Q2) How long do mountain bike brake pads last?
Ans.: There are a few factors that will determine the longevity of your braking pads but no concrete indicator exists yet:
- Type of material. Sintered pads last the longest, over 1000 miles before needing a change. Resin pads can last around 600 miles in good weather conditions.
- Weather conditions. On drier weather pads are more likely to heat up faster, meaning that they will also wear out faster.
With all things said and done it is up to you, the cyclist, to determine the best course of action for your bike.
Consider the information that you have gained here today and combine them with your own experience of cycling in your desired environment. Consider the weather conditions you will be riding in, and the type of track as well. Finally, also consider your budget and your own level of cycling.
We hope that the answer should now be clear to you.