The Different Types of Bicycle Brakes
One of the undisputed most important components on the bicycle is the brake. Without these, of course, safe riding is not possible in traffic or in nature. It is therefore all the more important that everything fits here. After all, there are not only different braking systems, but also incompatibilities of some brakes with other components of the wheel. This problem also exists between different brakes, so you have to look closely to ride a safe and reliable bicycle. You will find everything you need to know here.
The Bicycle Brake Systems
Nowadays, three brake systems can be differentiated: rim brakes, disc brakes and drum brakes. In the past, there were also stamp brakes that pressed the tires with a rubber stamp. Fortunately, these are no longer found on any new bike and can therefore be safely ignored here. For the fans of high tech, an ABS system from Bosch is now also available, which should make driving on e-bikes even safer. You can find out which of the current systems is suitable for your purpose here.
When it comes to rim brakes, a distinction can be made between three systems: cantilever brakes, V-brakes and side-pull brakes.
Both V-Brakes and Cantilever basically consist of two separate brake arms, which are positioned to the left and right of the impeller and actuated by a cable. Cantilever brakes are pulled together by a transverse cable, whereas the arms of the V-Brake are connected to a brake cable that runs through a guide tube and bellows. Basically, the function is very identical, but the V-Brake achieves a greater braking force due to the larger brake arms.
Cantilever brakes, on the other hand, are usually somewhat lighter and are therefore used in lightweight construction projects. Both brake systems score with low pad wear (due to a lower braking force compared to disc brakes) and very simple maintenance. Therefore, these components are often found on trekking and city bikes. Thanks to the hydraulic adjustment of the brake pads, they grip much more strongly, but are otherwise mounted like a normal V-brake. Only the maintenance effort is increased if necessary, since the brake must be vented with a special tool.
Side pull brakes, on the other hand, are found almost exclusively on road bikes, since this type of brake only works with thin tires. As the name suggests, this system is operated using a cable attached to the side. There is a C-shaped arm and a Y-shaped arm that move against each other and thus press the brake pads against the brake flank of the rim.
Hardly any mountain bike or cyclocross bike is not equipped with disc brakes today. More and more road bikes are also relying on the snappy brakes, as the increased braking power can be a real lifesaver in unexpected situations. The higher braking force comes from the fact that the brake pads on the disc brake achieve significantly higher friction values. Hydraulic actuation also plays a role in many brake calipers. The oil in the line cannot be compressed, which means that (including the lever ratio of the brake lever) large forces can be transferred to the brake pads. Therefore, disc brakes can usually be operated with one finger and can also be very easily metered. Lower braking power often occur with rim brakes, since the braking process triggers an elongation of the brake cable. This can also be seen on disc brakes that operate using a cable.
2 or 4 pistons?
When it comes to braking power, it is also crucial whether you drive a 2- or 4-piston brake. The piston is the component that is pressed out of the brake caliper by means of hydraulics (or mechanics) and transmits the force to the brake pad. Of course, four pistons apply more force to the pads and ultimately to the brake disc than two pistons can. Especially on downhill, enduro and e-bikes (because of the increased weight) you like to install the powerful versions. XC, marathon and trail bikes as well as cyclocross and road bikes, on the other hand, get by with the 2-piston variant. After all, the larger brake calipers also weigh a little more than you can’t use on a road bike.
The whole advantages of disc brakes are unfortunately bought with a few disadvantages, which are accepted for the improved performance. One relates to the increased maintenance effort should the brake pull air or water. The brake must be vented then using a special tool that differs from manufacturer to manufacturer.
By using different brake fluids one tries to counteract the vulnerability. Many manufacturers rely on DOT. This brake fluid can bind water, which is to prevent the pressure point from weakening. However, due to its binding capacity, DOT must be replaced approximately once a year, otherwise the bound amount of water can increase the fluid volume in the brakes so that it can no longer be compensated for by the expansion tank. This can result in the brake pads already touching the brake disc before you touch the brake lever. When working with DOT, it should be noted that the liquid attacks skin and paint. Mineral oil, on the other hand, does not bind water and therefore remains qualitatively equivalent for a long time. However, mineral oil brakes draw air faster, which has a negative effect on the pressure point and makes it necessary to bleed the brake. During service, DOT fluid should never be filled into a mineral oil brake, as this can destroy the seals.
Brake discs are available in many different sizes, types and with different fastening standards. The most common sizes are 140mm, 160mm, 180mm, 200mm and 203mm, whereby small discs are intended for cyclocross or road bikes, while the large discs are mainly used on enduro and downhill bikes.
Before retrofitting a larger disc on your bike, you should definitely check whether the frame or the suspension fork is suitable for the disc brake. Most manufacturers provide information in their manuals. In most cases, a pane that is too large cannot be used at all. You can tell that from the fact that the disc grinds on the fork.
Another difference between different brake discs is the design, which refers to single or multi-part assembly. The classic brake disc is made from one piece, but there are also multi-part discs (e.g. Shimano Ice-Tech discs) that use different materials on the friction ring and on the screw connection to enable better heat conduction, push the weight and reduce noise.
There are three different versions of the brake pads: organic, semi-metal or sintered metal pads. The individual versions can have different compositions depending on the manufacturer, which can lead to different values in terms of durability, braking power and noise. In general, however, it can be said that organic pads are very easy to dose, give less heat to the braking system and less squeak. In contrast to sintered metal coverings, wear is increased. Sintered metal tends to squeak. Semimetal coverings show the least wear and tear, but they are known for an unpleasant noise.
The types of flooring mentioned can also be applied to various carrier plates. Here aluminum, steel and titanium have established themselves, whereby these differ in thermal conductivity and weight. In order to conduct the heat even better, some manufacturers equip their rubbers with cooling fins. It is important for all rubbers that they are carefully braked down before the first “serious” use. Many manufacturers recommend braking almost 30 times at a moderate speed (approx. 30 km/h) to a standstill. The purpose of this is to grind off microscopic bumps on the surface of the pads and discs. If you do not do this, you will only brake at these quasi invisible tips, which can lead to extremely high temperatures and thus to the brake pads glazing.
Almost only disc and rim brakes are used on modern bicycles. The drum brakes (or coaster brakes), which were previously widespread, can only be seen today on isolated city bikes and in a somewhat larger number of children’s bikes.
The system is largely located in the rear wheel hub, where the torque of the rear wheel is transmitted to the frame by means of a torque arm when the pedal is stepped back (therefore stepping back). While it offers some advantages on the design side, such as the locked, weatherproof function and braking without releasing the handlebar grip, there are still some disadvantages. It is crucial here that drum brakes simply do not reach the braking force of modern disc or rim brakes. In addition, they tend to overheat on long descents and repositioning the crank position is only possible with great difficulty. The maximum braking force is only reached with certain pedal positions, which can lead to problems. They are still occasionally installed on city bikes, as the weatherproof function is very practical here. Supplemented by a classic front brake, the braking force is also strong enough for city traffic or for trekking tours. In addition, the drum brakes are very inexpensive.
The Bosch ABS System for Bicycles
With the electrical bicycles, stability programs are finally making it onto the bicycle. The first ABS system that is ready for series production comes from Bosch, which has been the market leader in the motorcycle sector for many years. Based on the motorcycle ABS, the bike is equipped with an ABS system on the front wheel and a lift control on the rear wheel. A wheel speed sensor on the front wheel detects whether the wheel is about to lock up. If the system detects a blockage, it automatically reduces the brake pressure and thus optimizes driving stability. The same aim is also pursued with the withdrawal regulation. This monitors whether the rear wheel is lifting and in this case also reduces the brake pressure on the front wheel for a short time. This means that even in very difficult situations, you can always brake safely.
This system can show its advantages, especially on slippery and loose surfaces, since the brief reduction in braking force leads to traction between the tire and the ground. This means that you slide away less quickly in extended curves and simply decelerate in a more controlled manner.
The Bicycle Brake Assembly
Brakes like any other component, must be fitted in the right place. It is important to ensure that the appropriate standards are available on the frame and fork.
Check your wheels
If you choose a rim brake, the rim must have a braking flank. This is mostly visible as a bare metal surface on the outer wall. There is therefore no paint to offer a suitable surface for the brake lining of the rim brake. The brake pads can only generate sufficient friction on an unpainted surface, so that decent deceleration occurs.
The use of disc brakes, however, is not dependent on the rim, but on the spoked hub. This requires a special holder to mount a brake disc. There are generally two common systems here: Either you have a 6-bolt hub and therefore also need a 6-bolt disc, or you have a Centerlock hub that also requires special discs. With the 6-bolt hub, the disc, as the name suggests, is attached using six small screws. With the Centerlock hub, the disc is mounted using a locking ring that is tightened using the same tool that is required for the cassette or bottom bracket. Assuming you have the right tools, assembling a Centerlock disc is a bit easier or faster. In addition, the hubs are mostly lighter due to the inclusion, so that there can be a small weight advantage.
Assembly on the fork and on the frame
Caution is also required on the fork. For the Cantilever brakes and V-brakes, a suitable base must be available on the fork’s dip tubes or on the seat stays. This is usually referred to as a cantilever base. The mount consists of two threaded sleeves that are screwed in orthogonally to the dip tube. The Cantilever brakes and V-brakes are placed on these sleeves and finally screwed on. Side pull brakes, on the other hand, are not mounted on a cantilever base, but by a screw in the fork crown. Basically, it is the same attachment with which fenders or reflectors are attached to the fork. In the case of lightweight carbon forks, it is important to ensure that the brake has been applied with the correct torque. Otherwise, it can be damaged quickly.
There are three standards for disc brakes: IS2000, Post Mount and Flat Mount. With the Post Mount and Flat Mount Standard, the brake caliper is fixed with vertical screws from above or below, but with the IS2000 Standard from the side. Because the brake caliper on the Post Mount Standard has elongated holes, the caliper can be aligned very well with the disc. There are also adapters for all common disc sizes, with the Post Mount brake moving further and further away from the fork or frame. With the Flat Mount Standard, however, the brake is moved in the direction of the frame or the brake. This corresponds more to the aerodynamic requirements of a road bike, which is why the standard especially has already been well received here. The screw connection on post mount and flat mount pliers is also more advantageous compared to the forces that occur, since hardly any shear forces occur here. IS2000 offered its advantage for a long time in that pane sizes of less than 160mm could also be installed. However, this is possible with both flat mount and post mount recordings, which is why the IS2000 standard is becoming less widespread.