Disc Hydraulic Bicycle Brakes
Disc hydraulics are very similar to their mechanical counterparts. The main difference is that the force applied to the brake lever is transmitted to the pads not with a cable, but thanks to DOT4 brake fluid (on Avid, Hayes, Helix brakes) or mineral oil (on Shimano brakes). Next, consider the design of hydraulic disc brakes.
- Brake handle. Actuates a piston that presses on the brake fluid.
- Brake lever adjuster. As with disc mechanics, it is designed to adjust the position of the handle relative to the steering wheel.
- Master cylinder. It consists of several parts. An expansion tank with a lid serves as a brake fluid storage. The cap is used when filling and bleeding the brakes. Inside there is also a piston with a cuff and a return spring.
- Hydroline. It is a durable hose that connects the master cylinder and the caliper.
- Caliper. A mechanism that, when pressure appears in the hydraulic line, activates the pistons that push the brake pads.
- Brake pads. Used to convert frictional force into thermal energy, thereby stopping the bike.
- Adapter. The part that attaches the brake caliper to the fork or bike frame.
- Rotor. It is a perforated metal disc, on which, when the handle is pressed, the pads rub.
How to set up mechanical disc brakes on a bicycle
Adjustment of the disc mechanics is required to be done: after installing new pads, cable, rotor or other brake components; in the case when the rotor rubs against the pads; when it is required to eliminate a large brake lever travel, etc.
- We check the tightness of the bolted joints at the points of attachment of the adapter to the frame and the rotor to the bushing.
- Loosen the lock nut and tighten the cable tension adjustment on the handlebar until it stops minus 1-1.5 turns. Then tighten the lock nut. We do the same on the adjustment, which is located on the caliper. Next, unscrew the cable retainer, and, pulling the cable by hand, tighten the retainer bolt back. (If you have already done these operations when installing a new brake, then you do not need to repeat these steps).
- We loosen the bolts that attach the machine to the adapter (for easier setup, you can remove it completely).
- We adjust the position of the fixed (static) and movable shoe. The purpose of this procedure is to achieve an equidistant position of the pads from the center of the caliper slot so that the rotor can fit between them with minimal clearances. To adjust the fixed shoe, loosen the locknut (if any), and rotate the bolt that adjusts its position. To adjust the movable one. rotate the cable tension adjustment on the caliper. After the distance is set, tighten the static block retainer. If for this procedure you removed the machine, then you should install it in place, but do not tighten the mounting bolts.
- We set the correct position of the caliper relative to the brake disc. To do this, the bolts that attach it to the adapter must be loosened so that it can walk relatively easily left and right. We press the brake lever all the way and fix it with electrical tape, wire, rope or other improvised means. Next, slightly wiggling the caliper with your hand, screw it to the adapter, alternately tightening the bolts.
- After performing the above operations, in 80% of cases the rotor will shuffle against the deck (s). We determine which of them it clings to, and adjust the distance by adjusting the cable tension on the caliper (in the case of friction against the movable block) or by rotating the bolt (if rubbing against the static one). The clearance on both sides should be minimal, at which the rotor does not touch the pads.
You can watch a detailed process of setting up disc mechanical brakes in this video.
There are cases that after setting up the mechanical disc brakes of a bicycle, the rotor “strikes” against the pads in one (or several) places. This suggests that you have it slightly deformed. In this case, you need to align it. This can be done directly on the bike without removing the rotor. Determine the place where it touches the pads by slowly rotating the wheel. Pay attention to which side the rotor is deformed. Then, we turn this section so that access appears to it, and we bend it in the opposite direction from the place of friction. Be careful not to make it worse. Do not apply too much pressure to the rotor. It is better to repeat this operation several times, gradually adding pressure.
Varieties and models of bicycle brakes
Brake adjustments on a bicycle can vary. In each situation, it is worth looking at the type of braking system. Most often, cheap bicycles are equipped with mechanical rim brakes, or, as they are also called, V-brakes.
Tightening the Brake
“They are easy to use, cheap and easy to replace. But, unfortunately, everything cheap has its drawbacks. The rim brake is not a priority in its class. This is due to its design. The pads often do not clamp the moving part as it should, so the braking distance becomes quite large. But expensive mechanical brakes can be quite competitive. In general, adjusting V-brakes on a bicycle does not require much effort, special techniques, so this class is suitable for beginners and amateurs.
The springs that are part of the mechanical rim brake system are also responsible for the distance between the wheel and the block. But, unlike a nut with a cable, they allow you to adjust the distance down to a millimeter. That is, more precisely. The spring tension can be changed with a single bolt that is screwed on and off every now and then. This bolt is located on both sides of the brake. Therefore, when a situation arises that one side touches the rim, and the other is separated, you just have to turn the bolt. and everything will fall into place. When this element is twisted, the spring becomes “harder”. Consequently, the distance will increase. If you unscrew the bolt, the spring will weaken. From this, the distance will decrease. So, by adjusting each element, you can achieve perfect accuracy.
First of all, we unscrew the brake rotor from the hub and check it for deformation. This can be done by placing it on a flat surface (glass, mirror, etc.) and inspecting it. If the rotor is loose, it should be aligned before adjusting the disc brakes. If the deformation is insignificant, then this operation can be performed when adjusting the brakes.
Adjusting the front brake on a bicycle
The hardest part lies ahead. Do not be afraid, you just need to concentrate. So, you need to adjust the distance between the pads and the wheel. It is important. Again, action monitoring is similar for the rear and front brakes. It is worth remembering: if the distance is too large, then the clamps will not fit well. Therefore, there will be no inhibitory effect. If, on the contrary, you leave little room for the brakes, they will strike the rim. This will quickly wear off the pads, and the wheel will constantly brake. In general, you can adjust the distance between the pads and the rim using one nut, which is located on the levers, on top, where the metal cable is attached.
It should be unscrewed, thereby loosening the grip. From this action, the levers will disperse, do not be afraid. With the force of the hand, you need to lean against the rim. Then squeeze the brake lever so that it does not reach the steering wheel for a couple of centimeters. Keeping the levers in the same position, screw the nut back. Adjusting the brakes on a bike doesn’t stop there.
First stage. Adjusting the position of the brake levers on the steering wheel
Oddly enough, the first thing that needs to be adjusted is the position of the brake lever on the steering wheel. Further adjustment of the entire brake system will depend on its position. To do this, loosen the handle securing screw for a few turns and set it to a comfortable position. the brake lever should be pressed by the second phalanges of the fingers. Adjust the main position (distance to the handle) of the brake lever to a position convenient for you using the adjustment screw.
Brake Problem Symptoms and Adjustment Frequency
First of all, it is necessary to check the performance of the brake system.
- Raise the front wheel so that it does not touch the surface. Give it rotation and check if the brake pads touch the rim for a short time and if there are no extraneous sounds. If this happens, then the centering of the wheel is disturbed. it has a “figure eight”. Before proceeding with further verification, it is necessary to eliminate this malfunction.
- During rotation, press the brake lever. the brake pads should work instantly and the wheel should stop. If there is a delay in braking or wheel slip, then a brake adjustment is required.
- Raise the rear wheel off the ground and repeat the above procedure.
Since the elements of the brake system are in close contact with the environment, check the appearance and condition of the brake pads and control cables. It is necessary to clean them of dirt and pay special attention to the condition of the cables. damage and rupture of even one strand can cause trouble, so they must be replaced.
So, the performance of the braking system has been checked.
When do you need to adjust and adjust the brakes?
- After purchase and a small run-in under load, inspection and adjustment of all systems is required. including the brake.
- After mechanical impact on the bike. shocks and falls.
- After long-term storage. Especially in unheated rooms.
- During the movement, extraneous sounds appeared. knocking and creaking, or a periodic whistle.
- The response of the braking system to control has changed. delayed response or, conversely, release.
The performance of the braking system is especially important if you have a mountain bike.
Consider the adjustment procedure for the most common bicycle brakes. mechanical rim brakes.
Types of brakes and the need to adjust them
Brakes are the main accessories for a bicycle and they are divided into two types depending on their effect. The first and most common type is rim, the principle of their operation is a mechanical effect on the wheel rim to reduce speed and rotation and stop. The second, not the most common type, is disk. Depending on the type of force transmission from the brake lever to the brake mechanism, the brakes are divided into mechanical and hydraulic. The following are guidelines for adjusting mechanical brakes.
First of all, you need to prepare the tools, place the bike vertically and secure it in special supports-racks.
Stage four. Setting the brake stiffness (adjusting the brake cable)
At this stage, it is necessary to establish a comfortable and reliable operation of the brake system, depending on the pressure on the brake lever located on the steering wheel. The position of the brake lever was established at the first stage of the system adjustment. Now you need to adjust the tension and, if necessary, the length of the cables.
To do this, simply press the brake lever. The pads should be pressed against the rim with minimal lever action. If necessary, adjust the length of the lever stroke, as it is convenient for you, using the tension nut, which is located on the lever itself. Do not set the stroke large, this is not recommended by all specialists.
All the necessary work has been completed. It remains to check the performance of the brake system, which is necessary.
Stage three. Installing the brake levers
Pads are installed on both sides of the rim, and their correct operation requires centering the levers located on both sides of the wheel.
- Press the brake lever on the steering wheel and control the simultaneous contact of the pads with the rim.
- Press the brake lever on the steering wheel and control the simultaneous contact of the pads with the rim.
- If there is an advance in pressing one of the pads, adjust the tension of the cable.
- Each lever has a special tension adjustment screw. If the block touched the rim earlier, then it is necessary to increase the tension of its spring, or reduce the tension of the opposite.
Does the touch occur at the same time? Then we go to the final stage of setting.
How to adjust mechanical disc brakes on your QuietKat
Adjusting the brakes on a bicycle
Adjusting the brakes on a bicycle should be carried out regularly. such maintenance will guarantee the safe operation of the vehicle. There are two main types of brakes on modern bicycles. rim and disc brakes, but disc brakes can be mechanical or hydraulic. The process of their maintenance will depend on what type of brake system is installed on a particular bike.
How to check and adjust the brakes
There are clear instructions for checking and adjusting the brake system of a bicycle. If you adhere to it, then the whole process will take little time and will be effective.
Procedure for checking and adjusting the brake system of a bicycle:
- Dry brake test. It is necessary to raise the front wheel and, having unwound it, press the left brake lever. If the wheel comes to a sudden stop during this test, the braking system is in order and no maintenance is required. It is worth considering one nuance. if the brake lever touches the steering wheel, then you just need to pull the cable. The operability of the rear wheel brake system is checked in the same manner. To tighten the cable, you need to use curly bolts. just tighten them a little and, if only minor adjustments are required, this will correct the situation. It often happens that such a minimum adjustment does not work. in this case, we look where the end of the cable is on the bike (it is always longer than necessary in advance), unscrew the bolt that holds it. It remains only to tighten part of the cable with pliers and tighten the bolt, applying the possible force.
- Checking the brake pads. After the brake levers have been tested, the condition of the brake pads should be carefully examined. However, the order of action can be changed. first work with the pads, and then with the handles.
The setting of the brake system for rim and disc type is different, since different rotating mechanisms and pads are used.
Adjusting the rim brakes
Mountain bikes use a v-brake braking system. by its example, we will consider the principles of tuning, as it is also available on other bicycles with rim brakes. The difference can only consist in a different arrangement of bolts and screws that will need to be tightened / tightened.
Note: it is important to observe three main rules:
- the pads should be parallel to the rim;
- the gap between the rim and the block should not be more or less than 1 mm;
- the pads should be symmetrical in relation to each other.
How to achieve these guidelines when adjusting rim brakes on a bicycle:
- You need to find a hex nut. it fixes the pads. To loosen it and set the brake pads in the desired position, you will need to press the brake lever and watch how the shoe touches the rim. By releasing the brake lever, the shoe can be set to the desired position. it moves up, down and at an angle.
- The distance between the block and the rim of the wheel should not be more than 1 mm, although in some models of bicycles there are also 2-3 mm. exact information about a particular vehicle can be obtained either from the instructions for it, or on the Internet for technical characteristics. It should be noted that braking of the wheel should occur even with the minimum pressing of the brake lever. That is, if the wheel stops only when the brake lever is fully pressed “all the way”, then this is incorrect.
After carrying out all the specified work, it is imperative to check the operation of the brake system. First, this is done at idle speed. lift the front wheel up, spin it up and press the handle sharply, then do the same with the rear wheel. The next step is to check the operation of the brake system “in action”. get on the bike and ride 3-5 meters, braking sharply. If the bike stops even when the brake lever is pressed slightly, then the system has been serviced correctly.
Setting up disc brakes
As a rule, adjustment of disc brakes consists in periodically tightening the cable. But often you have to replace the pads, however, on disc brakes they wear out longer than on rim brakes. First you need to find out which specific disc brakes are installed on the bike. brake pad adjustments for hydraulic and mechanical systems will differ.
Experts recommend taking note of the following points:
- If there are hydraulic disc brakes on the bike, then replacing the pads may not be necessary. they are able to do it on their own. But one nuance should be taken into account. if the hydraulic system is closed, then you will have to adjust the pads manually. for this, special valves are provided.
- If you have to adjust disc mechanical brakes, you will need to pull the cable according to the above instructions and check the location of the pads. the distance between them and the disc should be within 0.2-0.4 mm.
- In order to adjust the pads with disc mechanical brakes, you need to use special bolts. by tightening them, you can see how the pad moves. You need to be especially careful when setting the distance between the pad and the disc. 0.3 mm is too small, it is easy to make a mistake.
After carrying out the work, be sure to check the operation of the brake system in action. ride your bike for a few meters and try to brake. If the cable was overtightened, or the pads are too close to the disc, then too sharp braking will occur. this is a “surprise” in which the cyclist begins to move forward, but without his vehicle. Therefore, when driving for a test, you need to be extremely careful and careful, if necessary, the disc brake system is adjusted again taking into account previous errors.