Disc brakes are a feature that has existed for decades for vehicles, but has only recently popped up in the world of cycling. In 1997, Hayes created the first bicycle disc brake, intended for mountain bikes. It didn’t hold. Nobody wanted an overpowered new brake, when V-brakes were working perfectly well. Hayes kept on pushing their products, though.
People didn’t accept the fact that disc brakes were the next logical step, just as they had been for vehicles. They preferred to get along on age old technology that didn’t even function well. While the V-brakes were indeed serving the masses quite well, they had a number of significant disadvantages, especially on mountain bikes.
Then the bike company Trek installed a Hayes disc brake on their 8900 hardtail mountain bike. With a company as famous as Trek (and Fisher) backing their product, the Hayes Mag disc brake finally got its big brake (pun intended).
Disc Brakes in the World Today
In the present day, nearly all mountain bikes use disc brakes. The V-brake has been relegated back to road and touring bikes, and even then it is going out of style. People have finally come around and realized that the disc brake is simply better in every way.
Of course, some cyclists still use the old brakes on their mountain bikes because they want to stay “old-school” or simply because they can’t be bothered buying a new mountain bike that is compatible or comes installed with a disc brake.
This is however one of the best choices you can make in terms of stopping power, control, and safety. Since disc brakes are a relatively new technology, not many people are sure how exactly they work, even though most people have some sort of basic understanding of the entire thing.
How a Disc Brake Works – The Technical Jargon
The science behind how disc brakes work isn’t that difficult to understand. However there are some technical terms that you should get familiar with, especially if you plan on working with disc brakes a lot. You need to know exactly what to ask for at shops and what to talk about when whining about your bike with other cyclists.
In the same way that non-cyclists have trouble understanding what a fork is, you will have a little trouble getting the technical jargon of disc brakes down your throat. A few commonly used terms that you will need when dealing with either type of disc brake are right here.
Types of Disc Brakes
There are two main families of disc brakes, both with their own specific sets of perks. People elect to ride with either one of these, depending on their requirements when they go mountain biking. The two main types have both been around for a while:
- Mechanical Disc Brake – These are currently the more popular type of disc brake for the average mountain biker. Mechanical disc brakes operate on the same principle as normal cantilever and V-brakes. They use traditional cables and cable housing to actuate the brake.The mechanical disc brake offers a number of advantages over its counterpart. One of the main perks of the mechanical disc brake is that the cables are far easier to install, since everyone has used V-brakes at some point in their life with bikes. Adjustment of these cables is also easier. Replacements to the cables can be found very easily, at any bike shop around the globe, because the same cables are used.The disadvantages to cables in mountain bike disc brake systems is their exposure to environmental conditions and their vulnerability. The cables and their housing can be very susceptible to rust, especially when biking across wet conditions a lot.
Another drawback is the fact that cables can stretch with prolonged use. This means that they require constant adjustments to make sure that the brake is always in tension. You don’t want to be going downhill and find out that the brake has a little lag to it.
- Hydraulic Disc Brakes – The hydraulic disc brakes are a more recent addition to mountain bike disc brakes. Instead of cables and their housings, the hydraulic system uses hoses, reservoirs and hydraulic fluid (brake fluid) to actuate the calipers of the disc brake.The advantage of the hydraulic system is that it is closed off from the environment. The seal prevents dirt and debris from the off-road trail entering the brake fluid or the hose and cylinder. They offer far more power and control when it comes to the actual braking process than their mechanical counterparts.They do have a couple of drawbacks. They have to be professionally fitted. You can’t just install a hydraulic brake at home if you are an amateur. The smallest air bubble in the system could cause the lever to lock. Removing the air is called “bleeding” and it must be done with precision.
How Disc Brakes Work
Disc brakes work in a very simple way. Normal V-brakes grip the rim with the brake pads when squeezed. The friction of the pad on the rim causes the kinetic energy of the bike to be converted into heat energy, and the bike slows down and stops.
The disc brake works in pretty much the same way. However, it does not attach to the rim. Instead a circular disc is attached to the wheel hub. The fork has calipers with brake pads attached to it and linked to the actuation system, hydraulic or mechanical.
When the brake lever is squeezed, the calipers compress and touch the brake pads to the disc at the bite point. The same principle as the V-brake is applied, except all the friction and heat energy is generated at the disc instead of the rim of the bike wheel.
Mechanical disc brakes use the standard brake cables everyone knows and loves to actuate the calipers. As you know, these offer advantages mainly in the terms of cost and simplicity, but are also not that great in extreme weather and terrain.
Hydraulic disc brakes use a plunger to push brake fluid down the hose when the lever is pulled. This pushes the caliper onto the disc. While this is a very basic explanation of hydraulics, it is how the brake works. This makes for a far smoother braking process than mechanical braking.
Whether hydraulic or mechanically actuated, disc braking offers a number of significant advantages over the older, industrially accepted V-brake, especially when it comes to mountain bikes and their need for durable all-terrain components.
The Advantages of the Disc Brake
- Strength – Disc brakes are stronger and more durable that normal V-brakes. This is because they are a separate attachment to the wheels, instead of being in tandem with them. The discs are made out of a stronger material (like steel) than the rim. This means they are less prone to cracking.
- All-Terrain effectiveness – The main selling point of mountain bikes is that they can be used in any kind of conditions. With the right kind of tires and the right equipment, they can be ridden in slippery, wet trails, muddy off-road tracks and even on snow and ice.Because they are used in nearly every terrain known to man, mountain bikes need to have brakes that aren’t affected by the weather. While rim brakes can start rusting due to exposure to wet terrain, disc brakes that have sealed housing do not have this problem. The wetness does not affect their efficiency or stopping power.The same goes for muddy or icy terrain. A V-brake would start slipping in mud because the rims would be covered in the stuff. In snow, the cables could ice up and crack. However, in a disc brake (and mainly a hydraulic brake) the mud does not affect the disc as much because it is nearer to the center of the wheel, attached to the wheel hub.
While mud does get onto the rotor, the larger surface area of the brake pads on disc brakes allows for them to be more effective even in these conditions. Mountain bikes without disc brakes are a safety risk, because of their lower effectiveness off-road.
- Off-Road capability – In a typical mountain bike ride, you would go along some pretty bumpy trails. Riding over rocks and holes and other bumps is quite normal for mountain bikers. These conditions could damage the rims. They could get bounced out of shape.With a V-brake, this would be a very large safety risk. A warped rim means that the brake pads won’t be in constant contact with the rim. This means that the power of the brakes are cut in half, and it could fail at a crucial moment.A disc brake, however, does not run this risk because it does not depend on the rim. The wheel could be bounced and hit until it was a square, and the disc brake would still be just as effective because the pads clamp onto the rotor instead of the rims.
- No tire overheating – One great advantage of the disc brake in hot weather or even when coasting downhill is that it does not overheat the rim. The large amount of heat generated when a V-brake is applied at high speed can heat up the rim enough to weaken the material of the tire and cause it to blowout when going at high speeds over rough terrain.Since the disc brake isn’t connected to the main rim, only the disc heats up during operation. The holes drilled into the rotor provide a far higher rate of heat dissipation than a rim would. This means that your tires will be safe and your disc brake will heat up less than a V-brake would.
- No rim wear – When going in terrain that is sandy or muddy, particles of sand and other debris can get stuck to the rim. When the brakes are applied, any debris caught between the pad and the rim can scrape the rim during the braking process. If this is done repeatedly, it wears out the rim, weakening it and making it more susceptible to cracking.With a disc brake this isn’t an issue. This means that you will be replacing your mountain bike wheels less frequently if you’re an enthusiast with disc brakes instead of the traditional brakes. This can be a major perk in terms of cost effectiveness.
- Multiple wheel configurations – when you ride off road in many types of weather and terrain conditions you are going to have to replace or switch out your wheels a lot. For example you can’t use the same wheels for mud that you use on icy roads or tarmac. Different wheels with different thicknesses and grip patterns are required for the real mountain biker.With a disc brake, you don’t have to go through the time consuming process of adjusting the brake pads so that they fit different sizes of wheels as you fit them. Instead, you just have to reattach the disc brake setup to the wheel hub after installing the new wheel and you are good to go!
- Hydraulic brakes – Hydraulic disc brakes are probably one of the best inventions in terms of bike brakes. The braking process is far smoother with a hydraulic disc brake than it ever could be with cables. If bled right, hydraulic disc brakes are definitely something worth adding to your mountain bike.Some hydraulic brakes even automatically adjust the pad as the rotor wears down over prolonged usage. This means that you need to make less adjustments to the brakes when using this type of actuation. One of the best parts of this is that when the rotor does wear down, it is a little like a one size fits all standard of disc brake rotors. You can easily find a replacement, even if the specific model of disc brake is no longer in production!
Disc Brakes: Squealing Into the Future
Disc brakes don’t actually squeal. It is an expression. However, if you are an avid all-terrain mountain biker you are definitely going to want to think about replacing your old V-brake configuration with disc brakes. In spite of them being heavier (who cares about a little extra weight? It’s a great workout!) They add a bunch of features to mountain bikes.
These include a higher level of safety as well as a higher overall ride quality. With their ease of use, strength and versatility when it comes to maintenance and installation you can be sure that the disc brake is indeed the brake of the future, replacing the relic that is the V-brake in off-road riding.