For brakes, both mechanical and hydraulic, there is only one action vector - to stop the vehicle. But there is a whole set of questions regarding both types of schemes. It is worth considering the hydraulic brake in more detail . Its main difference from the mechanical one is that a hydraulic line is used to drive the pads, not cables. In the variant with hydraulics, the brake mechanism is connected directly to the handles.
Principle of operation
To understand how a hydraulic brake works, you need to consider its structure. A special oil or brake fluid under slight pressure is used to fill the hydraulic line. Pressing a special handle displaces the fluid from the hydraulic system, as a result of which it exerts pressure on the working cylinder mounted on the fork or bicycle frame. As a result of this, the brake pads and the piston are activated, which leads to the blocking of the wheel.
Everything is pretty simple. The hydraulic brake circuit provides a visual representation of the operation of the entire described system. Working with such a device requires the understanding that brake fluid is extremely toxic, which often causes severe poisoning. In addition, it is capable of adversely affecting plastic parts and paintwork.
Advantages and disadvantages of hydraulics
The wide distribution of such a braking system can be explained by the accuracy of dosing and the high speed of the reaction of the mechanism to pressing the handle. However, the advantages do not end there, but it was they that became for many athletes decisive in the matter of turning to hydraulics.
Another important point is the excellent endurance that hydraulic disc brakes have. No less significant is the accuracy of the operation. The system has proven reliable over many years of use in automobiles. Appropriate care allows you to make the hydraulic brake mounted on the bike much more reliable than the mechanical brake. A heightened sense of dosing power makes it possible to use the brakes as accurately as possible. It is simply necessary in extreme sports.
Among the shortcomings of the hydraulic system, several main ones can be distinguished. The cost of such a system is much higher in comparison with the mechanical one, therefore the price of a bicycle with hydraulics will be substantial. Such a device is a technological and very complex unit, which requires maintenance skills and a clear understanding of the design features. Not every biker has the necessary knowledge to independently disassemble and repair the hydraulic brake.
Careful relationships require components such as brake hoses and tubes. These are very weak spots that have a direct impact on the functioning of the entire system. Hydraulic brakes on a bike can be picky about the quality of the oil or brake fluid, so pumping should be done after a smart choice has been made. Quite often they are used in conjunction with traditional disk. It is worth saying a little about them.
Types of hydraulic disc brakes
The difference between a disc brake and a rim brake is that braking is achieved by clamping the disc, which is fixed on the hub quite rigidly with special pads, fixed on the rear of the frame and in front on the feathers of the fork. The main cylinder has a different design, so the hydraulic brake can belong to one of the following types: single-piston, double-piston with floating or opposed pistons, multi-piston. The third variety is mainly used. You can meet models that belong to the first type, but due to certain shortcomings they were almost completely replaced by the second and third types. Complex systems with many pistons are used for the downhill, where power plays a decisive role, not the simplicity of the design.
Distinctive features
If we consider the hydraulic brake drive, then it is appropriate to note the possibility of using oil or a special fluid. Each of the options has both disadvantages and advantages, but so far there is no unequivocal opinion on this matter. The caliper can be monolithic, due to which the design becomes light and rigid, and composite, characterized by lower price, but more complexity in terms of maintenance.
The hydraulic disc brake is reliable, but it is quite difficult to repair it in the field. True, it crashes in extremely rare cases. There are a number of problems associated with the fact that disc hydraulics have a very small gap between the blocks, and in the presence of strong contaminants they wear out many times faster. However, in this case, the mechanics cannot boast at least some advantage, since damaged pads cannot be adjusted on the go, and in the case of hydraulics this is carried out automatically during wear.
Disc brakes are significantly more expensive than rim brakes, their load on the hub during braking is greatly increased, although this issue can be called controversial. You should not delve deeper into this topic, it is better to talk about the manufacturers on the market of hydraulic brakes.
Brand Overview
Despite the fact that there are so many types of brake systems, a hydraulic brake is now quite common on mid-level bikes. With the growth of their popularity, a noticeable drop in prices can be noted. Therefore, it is possible that you decide to re-equip your bike with a hydraulic brake system. There are many examples of this, but we will give only a few.
One manufacturer is Shimano. Hydraulic brakes of this brand are presented in several lines. The most recent was Deore. Its characteristic is the stable operation of the main cylinder, convenient and pleasant to use handles. A cyclist can truly enjoy how the whole system works well and behaves obediently. The picture is slightly overshadowed by the rattling of the brake handle itself. The new collection is represented by two options for mounting the rotor: bolted and spire. Two types of blocks are supplied in one set - metallized and rubberized. Depreciation of the latter proceeds as quickly as possible. In general, it is a hydraulic brake of excellent quality, which costs the money spent on its purchase, namely, $ 50.
CLIM 8 CLARK`S brakes are characterized by the fact that when you buy a device for the price of a single-cylinder brake, you get a full-fledged multi-cylinder device. However, everyone knows that miracles do not happen, so the pen design is a little alarming here, but this parameter finds its fans. But the hydraulic hoses received reinforcement with metal and Kevlar.
The most interesting design, with six cylinders, is available from the caliper. This system is characterized by such a disadvantage as weight gain. In addition, during the installation process, you need to adjust the pads to the disks as carefully as possible.
The hydraulic brake is characterized by the fact that reviews about it can be found quite diverse. It is often said that such a system is quite picky in terms of service. However, this statement can be called controversial. This is not at all difficult, and you can see for yourself. In servicing the brake system, the most difficult job is to pump it. Almost every biker who uses hydraulics faces such a problem. You yourself can appreciate how complicated this procedure is.
Symptoms
The very first sign that the bicycle's brakes are malfunctioning is the fact that they brake themselves. This can be explained by the fact that there was a small amount of air inside the system. This could happen due to the fall of the bike, when the hydraulic circuit is opened, as well as with a low level of brake fluid in the tank.
Since the property of air to compress significantly distinguishes it from liquids, when it enters the system, it can work as a gas spring. As a result of this, fluid pressure is created, which activates the brakes. The rear hydraulic brake can engage in such an initiative if the working piston begins to jam. This may be due to water entering the hydraulic system. Another point that should alert you is the loss of elasticity of the brake handle in comparison with the early period of operation. And if hydraulics does not respond at all to your bike stop command, then there will be only one solution - immediate replacement of the entire system.
Diagnostics and repair
To understand what exactly happened to the brake system of a bicycle, several experiments are necessary. First of all, you need to remove the wheel on which this problem is noted. Next, you will need to make some efforts to clean the brake machine from dirt, which is easiest to do with a toothbrush. The main task in this case is to remove the pads.
After opening access to the working pistons, you must press them in with a screwdriver and then gently press the brake handle. Both pistons should extend forward. If one of them jammed, then it is required to use a repair kit to eliminate the existing malfunction. The piston system must be carefully inspected for various leaks. In the case of their presence, we can talk about the severe deterioration of the group of cylinders. Now you need to replace the pistons or special o-rings on them. In the end, you need to carefully inspect the entire hydraulic line. A good sign is the absence of kinks, dents and other injuries on it. If available, replace the entire hydraulic line.
Why is pumping necessary?
If you press the brake lever, and it goes to the flu, that is, its stroke is too large, but the pads do not move or do not reach the brake disc, then we can draw conclusions about the need for pumping. A similar situation is observed if the lever has too easy a stroke when pressed or completely fails. When the handle is abruptly pressed, and after the system is triggered, it does not return to its original position, it is also necessary to pump hydraulic brakes on the bicycle.
In these cases, the cause of the failure of the system was the air that was inside. First of all, it is required to find the place through which the transmission is carried out. It should be noted that this may be preceded by damage to the hydraulic fittings, weakening of the pumping fitting on the cylinder, and boiling of the liquid, which is associated with overheating. When the entire system is checked for fluid leakage, it will be possible to proceed to repair it.
If you need to pump a hydraulic brake, physics in this case speaks of the need to do this on a horizontal level surface. Pads need to be parted so that they do not reach the disk. Next, you need to unscrew the master cylinder, and then fix it horizontally. Each system features pumping may vary, so you should use the instructions, in which everything is described in detail.
Final work
Next, you need to put on a cambric pumping bolt, and then immerse it in a container to collect the remaining fluid. After that, you need to unscrew the cap of the expansion tank and fill it with liquid to the maximum level. You should press the brakes on your hand several times, but it is recommended to do this smoothly and slowly. It is required to press until tightness appears. Then, while holding the handle, you should unscrew the bleeding screw with the cambric and add liquid to the expansion tank. It is recommended to carry out such a procedure until the handle reaches the necessary level of rigidity. After that, you can tighten the expansion tank, and then remove all the tools. Everything is ready, now the brakes are fully pumped.
findings
As you can see, rumors about the difficulty of pumping are overly exaggerated. The hydraulic brake system is characterized by the fact that it has more advantages than disadvantages. But the real biker is not so important the principle of operation of some mechanism, but the fact that he has the ability to move freely in space. And the disc hydraulic brakes on the bike allow him that.
Have a good trip!