ABC mechanics: adjusting the brakes on a bicycle
There are several types of bicycle braking systems:
- rim. mechanical (vector, tick, cantilever) and hydraulic;
- disk. hydraulic, mechanical and combined;
- drum and stirrup.
Of these, only the first three systems are widely used. It can be noted that the adjustment of the brakes on a bicycle differs from the type used. Consider the most common cases. rim and disc brakes.
The disc brake system is a device that includes a rotor made in the form of a steel disc and a caliper. The last device is a caliper brake, the pads of which compress the plate. The force from the brake lever is transferred to this mechanism by means of a cable (mechanic) or using hydraulics.
Adjusting the brakes on a bicycle with a disc system can be done as follows:
- It is necessary to install the disc on the wheel hub and secure with eccentric bolts.
- Attach the adapter and caliper so that the last element does not fit snugly.
- By pressing the brake levers, you need to adjust the position of the pads, at which they retreat at an equal distance.
- When the rotor is clamped, the caliper is automatically installed in the correct place, and only after that it is necessary to fasten this part with bolts.
- Check brake pads for working condition. To do this, the wheel is scrolled by pressing the system knobs several times (more than 20). In case of friction of the rotor against the block (on one side), loosen the caliper fastening and move it in the direction of this bar. If this phenomenon is bilateral, here it is necessary to loosen the hexagon on the handle and tighten all the bolts.
Adjusting the brakes on a bike with a rim system involves two steps:
- Setting up the front device.
- Rear brake system adjustment.
The position of the handles can be adjusted according to individual parameters, so that it is convenient when you press this device. To do this, you need to loosen the screw with which this part is attached to the steering wheel. Then adjust the position of the handle and fix the element.
The handbrake is adjusted so that the pads are located at an equal distance from the rim (about 3 mm). This can be achieved by weakening the tension of the hold-down spring from the side of the weaker tension or increasing it from the other side.
The rear brakes are adjusted in the same way. Checking and adjusting the operation of this system will increase the service life of the bike, as well as secure traffic on this type of transport.
DIY disc brake adjustment
Until recently, bicycle disc brakes were considered something of an exotic. Today, many people, due to the many advantages, prefer this particular design. The topic of the article is the adjustment of disc brakes. Since the design of different systems is different, the adjustment algorithm will also differ. So, there are 2 categories of disc brakes.
- Mechanical. The transmission of the braking impulse is carried out mechanically, through a cable.
- Hydraulic. The bike is equipped with a special hydraulic line. The transmission of the braking impulse is carried out by the pressure of the liquid column.
Bleeding the brakes
To transmit the force required to press the pads against the rotor, mineral oil or an incompressible fluid is used in the hydraulic lines. Air, on the other hand, is distinguished by the fact that it is compressed, therefore, it should not be in the system. Otherwise, energy will be spent on compressing it, and not on pressing the pads.
This can be prevented in a ridiculously simple way. The syringe is half filled with brake fluid by connecting the caliper adapters and the hose to it.
Like a nurse, air is slowly squeezed out of the syringe by connecting it to the fitting (if the brake is Avid) or previously on the drain valve (Hayes brake) with a 6 mm wrench, and start pumping.
For Avid, you will need to squeeze the syringe tube with the red clip provided in the kit, for Hayes. keep the valve closed.
Next, they are engaged in the brake handle. The adapter provided by the manufacturer is connected to the syringe with the collected brake fluid and through the corresponding adapters to the drainage hole. For Magura / Shimano systems, it is done a little differently: they open access to the reservoir with brake fluid.
So that the piston does not come out of the caliper, it is necessary to insert a special tool that comes with the kit into the gap that exists between the pads, or cardboard, folding it several times.
A container or syringe attached to the caliper is squeezed very carefully by slightly opening the drain valve with a special tool. Squeeze until the fluid reaches the brake lever. To “expel” air, gently knock on the handle, caliper and brake hose. When the fluid goes without air bubbles, press the brake several times by closing the valve on the caliper.
The brake lever should move up to about half of the free travel. If so, you can close the brake drain on the handle. For Magura / Shimano, the reservoir is closed with a lid, the brake lever is set to the standard position. It remains to remove the brake fluid drips with alcohol.
Before starting maintenance, remove the wheels to remove dirt from the brake machines. For these purposes, you can use an ordinary toothbrush. After cleaning the caliper, you need to remove the pads.
How to Tighten MTB DISC BRAKES
A return spring, screw or cotter pin can be installed between the blocks, thanks to which the parts are held in place. When there is not enough space to remove the pads, this is done by gently pressing with a special tool (supplied). As a last resort, a wide screwdriver will do to spread the pistons all the way into the caliper.
Having freed the pads, they are removed one by one using pliers, inspect for a leak in the piston area. If it was not possible to completely dilute the pistons, they are pressed on with a 10-11 key, without touching the pin located in the center. In order not to “destroy” the pads forever, neither oil nor grease should get on them.
To check that the pistons extend normally inside the caliper and return back, it is necessary to press the brake lever several times. If they move in the same way, at this stage it is advisable to lubricate them, then, again, dilute them to the maximum with a key, pressing into the caliper.
If this is not observed, a repair kit or replacement of the caliper will be required. The bulkhead operation of this part is not easy and can be difficult for a beginner.
How to check the tightening torques?
When the pads are inserted, they and the rotor are cleaned, tighten the brake system fasteners, including the adapter fasteners, caliper, brake levers. Use a torque wrench for this purpose.
How to get rid of the squeak?
If there is a creak of disc brakes on a bicycle during braking, you need to follow the steps specified in the instructions below:
- keep the rims clean, i.e. clean them with gasoline, thinner, white spirit, which will help dissolve the worn-out rubber pads “stuck” to the rim and increase friction. If these procedures prove to be ineffective, and the squeak of the brakes on the bike does not disappear, you need to clean the rim surface with fine-grained or medium-grained sandpaper. The creak should disappear;
- clean the pads in a timely manner: you can use the mechanical method. scrape with a knife or other sharp object, sandpaper;
- control the correct installation of the pads relative to the rotor;
- make sure that the rotor is clean, to the state of which disc brakes are sensitive;
- you need to lubricate everything that turns on the bike. Need lubrication of the brake caliper, carriage, steering column, bushings, chains, ratchets, etc.
- In addition to the listed tips, so that the brakes do not creak when braking, the correct driving technique is important:
- to press the pads more intensively, i.e. to slow down in short, you need to learn to predict the braking distance;
- choose pads that are made of high-quality material (applies to disc and V-break brakes);
- dry disc brakes. After that, they will become smaller together. To this end, you can make a couple of emergency brakes, in which the pads will heat up, which will lead to the evaporation of water.
Adjusting the brakes (V-Brake)
Setting up the brakes means paying attention to every detail, from the brake levers to the brake pads.
First step. Adjusting the brake levers
Brake levers should be positioned so that they can be reached quickly and comfortably.
In order to adjust the position of the brake lever, loosen the fastening screw, place the handle as it is convenient for you and fix it.
Usually there is a screw on the brake lever, with which you can adjust the distance of the brake lever to the grip. adjust the position of the lever with it.
Second step. Position of the brake pads
It is easier to adjust the position of the brake pads as follows: press one of the pads with your hands close to the rim, adjust its position. Make sure that the block is not too low (the edge of the block is below the rim), but also not too high. the block touches the tire.
I would like to draw special attention to the next moment, since there is little clear written about it. Until the nut of which the shoe is fixed is not tightened, the shoe has three degrees of freedom: the washers form something like a ball joint.
(Pay attention to how many washers are there? That’s what they are for!). It is believed that the leading edge of the pads should touch the rim slightly earlier than the rear. Therefore, we do this: put a small gasket under the rear end (see fig).
This number of washers is needed to get something like a ball joint
Now you can tighten the nut that fixes the shoe.
Step three. Centering the positions of the levers
At this step, you need to fix the brake cable: so that the brake pads touch the rims at least a little if you press the brake lever. At the bottom of the levers there are special bolts that adjust the tension of the springs that press the pads against the rim.
We set it up as follows: press the brake and see which of the pads touches earlier. For the one that touched earlier, we increase the spring tension (or vice versa, weaken it on the other side). It is necessary to ensure that the pads touch the rim at the same time.
Fourth step. Adjusting the distance from the pads to the rim
I believe that this distance should be as small as possible. (1-2 mm. If the rim is even). But then the brakes will work very sharply. the slightest pressure leads to sharp braking. Therefore, the distance can be made a little more.
The distance is adjusted in two steps: first, due to the screw with which the cable is attached to the brakes. Then fine tuning on the brake lever.
The large washer acts as a lock: when it is tightened, the cable tension adjustment screw cannot be turned.
Why do brakes squeak when braking
Bicycle brakes differ from car brakes in that they are clearly visible, so the squeak during braking bothers owners more often. Bikes are usually equipped with brake or disc brakes, differing in design. Therefore, the reason for the creak may be different.
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.
Disc hydraulic brakes
In this case, the reason for the adjustment is the strong resistance of the wheel at the moment of movement, as well as when an extraneous sound or squeak appears.
The adjustment instructions in this case are as follows:
Adjusting Shimano Mechanical Disc Brakes on your Bike Friday
- On the caliper, the bolts are unscrewed, after which the handle is squeezed out to press the pads against the wheel.
- The next step is to check the position of the valves. They must be equally spaced from the rotor.
- Next, all screws are tightened.
- After locking the caliper, the handle is released. In this position, the block should not be pressed against the rim, be at a distance of about a millimeter.
- Quite often there is a situation where the pads are located at different distances from the rim. The problem can be solved by pressing one of the pads, after which the handle is worked through 10 times. Due to such actions, unevenness is eliminated.
The final stage involves setting the correct position of the handle, which controls the system. For this, a special adjusting hexagon is installed.
How to set up and adjust disc brakes on a bicycle
New bicycles are often equipped with rim brakes, or V-brakes, and Soviet bicycles have always been fitted with the only existing caliper brakes. Currently, this is due to the desire to reduce the cost of the design: it is no secret that many cyclists dream of changing the brakes to disc brakes as soon as possible. Often, even when choosing a bike, the costs for changing the brake system are included in the amount.
Below we will show you how to set up disc brakes on your dream bike.
Since the principle of operation of disc brakes is different, it is impossible to adjust them according to the same scheme. Brake disc mechanisms are:
- mechanical. In this case, the braking energy is transmitted mechanically, using a cable;
- hydraulic brakes, which have a specially laid hydraulic line, and the braking energy is transmitted by the pressure of the liquid column.
Bicycle disc brake design
In many ways, it is the design of the disc brakes that determines how tuning is done.
All devices fall into two categories:
- The mechanical device has a cable, due to which energy is transferred from the handle to the executive unit. In this case, a high force can be transmitted.
- Hydraulics are represented by the line through which the fluid transfers energy to the brake pads.
Before adjusting: preparing for tuning
The decision to adjust disc brakes on a mountain or road bike will only be successful if the brake system is diagnosed. By the way, the diagnostic measures for hydraulics and mechanics will be different. How hydraulic brakes on a bicycle differ from mechanical ones. we already had a conversation.
In short, in the hydraulic circuit, both pads push the fluid, acting on the caliper pistons, which results in clear modulation and easy handle travel. And in mechanics, only one friction lining is movable. It is brought to the disc by pulling the cable with the brake lever.
However, whatever the brake drive is, it is worth checking:
- Rotor for deformation. For 100% confidence in the flatness of the disc, it is better to unscrew it and put it on a flat surface. A rough estimate can be made while on the bike by rotating the wheel and estimating the distance to both pads through the slot in the caliper. Friction linings must be equidistant from the disc in any position.
- Brake pad wear and integrity. Remove the pads by removing the cotter pin and assess the residual thickness of the friction material. The surface in contact with the disc must be free of pits and dents.
- Cleanliness of pads and rotor. The presence of oil traces and accumulations of dirt on their working surfaces is not allowed. To clean them, you can use fine sandpaper (for example, “zero”) and rags soaked in any cleaner (acetone, ammonia).
- Wheel hub location in frame / fork dropouts. The bushing should fit freely into the seat and abut against the mating surface of the frame or fork. Distortions in the installation cannot be avoided, but they should be minimal, practically invisible. Micron skewing is immediately audible on the brakes in the form of rotor shuffling. This is why disc brakes need to be re-tuned after re-mounting the wheel.
It will not be superfluous to take a look at the state of the drive. With cable disc brakes, check the cable integrity. The end should not be unwoven, and the service life should not exceed 3 years. When replacing the cable, change the shirts. It is not necessary to lubricate it, but if you decide, then do it only with the help of a special lubricant that does not attract dust.
Nothing should leak on the hydraulics. Weaknesses are connections:
- Master cylinder. hydraulic line.
- Brake Lever. Master Cylinder.
- Brake caliper.M
These joints received the status of weak due to the use of cuffs, which dry out and leak over time.
Service technology: brake adjustment on MTB type bike
The level of safety, to a greater extent determined by the state of the braking system, depends not only on the class of components used, but also on the frequency of inspection and the frequency of adjusting the unit. Despite the complexity of its design, service is quite affordable for anyone interested in cycling.
Intermediate: Setting up mechanical (cable) disc brakes on a bicycle
Before adjusting any disc brakes, check:
- the accuracy of the wheel axle setting in the dropouts (seats) and the clamping force of the hub in the frame / fork;
- uniform tightening of the brake disc (rotor) and the brake unit housing;
- deviation of the rotor shape from the vertical plane (if necessary, align the rotor with an adjustable wrench).
The technology, including how to adjust disc mechanical disc brakes on a bicycle, is as follows:
- disconnect the drive cable from the brake machine (caliper);
- loosen the two screws securing the caliper to the brake unit housing;
- extend the fixed block (located closer to the wheel spokes) using the bolt located on the inside of the caliper;
- press the caliper so that the static pad is in contact with the rotor;
- tighten the screws securing the caliper to the body of the brake assembly (attention. the plane of the shoe should not be displaced from the plane of the rotor);
- by rotating the corresponding screw, achieve a minimum clearance between the fixed block and the rotor;
- rotating the lever to which the cable is attached, make sure that in the clamped position the rotor does not twist, but bends evenly towards the static block (in case of non-observance, the caliper setting should be repeated);
- install and fix the cable.
After the adjustment of the working unit of the disc brakes, the setting torque should be adjusted by rotating the adjusting drums near the brake lever and caliper.
For your information. On a properly adjusted deceleration unit, the central vertical section of the brake rotor should lie in the same plane with the caliper slot.
Types of brakes and features of their adjustment
On mountain bicycles, three types of brake modules have been used:
- rim (V-Brake);
- disk with a mechanical drive;
- disc with hydraulic drive.
As is the case with the derailleurs, it is advisable that the adjustment of the cable brakes on the bicycle is preceded by a detailed inspection of the control line elements. the cable and shirt. Before adjusting hydraulic disc brakes, it is recommended to inspect the hydraulic line for various damage and, if necessary, replace it with subsequent bleeding of the system.
The adjustment of all brake systems in some cases is preceded by the adjustment of the control handle (using the adjusting screws located in the product body). The purpose of the operation is to find the optimal resistance force and a safe location relative to the rudder.
Pro: How to Set Up Hydraulic Disc Brakes on Your Bicycle
The adjustment of disc brakes with a hydraulic drive is much easier to implement, in contrast to a disc-type retarding module using a cable as a force-transmitting element. The setting takes place in the following sequence:
- loosen the screws securing the caliper to the bracket;
- clamp the brake lever;
- make attempts to turn the wheel back and forth, thus centering the position of the caliper;
- tighten the screws securing the brake machine;
- in cases where the cylinders / pistons were serviced or a new machine is being installed, it is necessary to bring the pads to the rotor in working condition by sharply pressing the module control knob 15-20 times.
During the operation, problems and questions may arise how to adjust the brakes on a bicycle with hydraulic lines, expressed in the following:
- when rotating, the rotor touches one of the pads. it is necessary to slightly shift the caliper towards the rubbing pad;
- when rotating, the rotor touches both pads. it is necessary to remove them from the disc by slightly unscrewing the adjusting hexagon on the brake lever (it also determines the moment when the pads engage with the disc);
- when the handle is pressed, the pistons move out unevenly. it is necessary to remove the module, push the piston that moves out in a timely manner using a plate or a screwdriver and, fixing it, carefully push out the jammed piston, pressing the brake lever, and clean it;
- the pistons do not return to their original position. it is necessary to clean the entire system;
- the brake lever fails. it is necessary to bleed the system (if there are bubbles) or replace the brake line (if there are leaks).
Setting up a budget system: how to properly adjust V-brakes on a bicycle
Ideal for field repairs and cheap to operate, V-Brakes are configured in four steps. over, compliance with their sequence is extremely important. Before adjusting the brakes on your bike, disconnect the feed jacket from the right (for the front brake) or left (for the rear) lever by simultaneously pulling the metal cable guide and pulling the brake lever towards the rim. 1. The search for the optimal position of the pads relative to the rim is performed in the following sequence (the pads are adjusted alternately):
- using a hexagon, the screw securing the shoe to the lever is loosened;
- the block is tightly pressed against the rim;
- the search for the optimal location of the shoe is carried out. its outer and inner edges should be coradial to the wheel circumference;
- the block is slightly pulled against the lever.
Debugging the location of the working plane of the shoe. When adjusting the lever brakes on a bicycle, this transition is given special attention: it is necessary to ensure that the front edge of the pads touches the rim before the rear. To do this, under the rear edge of the shoe, fit some solid object with a thickness of 1-1.5 mm and press it against the rim. Then the fixing nut is finally tightened. Next, repeat the transition for the second lever.
Centering the position of the levers (selection of the force of the springs of the levers) The task is to ensure simultaneous adherence of the pads to the rim. Regulating elements. screws located on the left and right levers, near the place where the latter fit on the fork. The cycle of preparation for commissioning includes the following transitions:
- install the cable guide in the tube holder on the arm;
- if the cable was disconnected, it must be fixed with the corresponding screw on the lever.
Operations on how to adjust the force of the brake springs on a bicycle are as follows:
- clamping the brake lever, the moment of contact of the pads with the rim is monitored;
- on the lever with the block that touched earlier, it is necessary to strengthen the spring by tightening the corresponding screw (you can loosen the spring on the second lever).
Setting the distance of the stationary arrangement of the pads from the wheel rim (selection of the optimal tension of the cable) The task of the stage is to adjust the sharpness of the brake mechanism. The operation is performed in the following sequence:
- the adjusting drum turns almost all the way (you can leave 2-3 threads);
- unscrewing the screw securing the cable to the brake lever, slightly tightening it and tightening the fixing bolt again, the optimal distance between the pads and the rim is found (1-2 mm);
- if it is necessary to slightly increase / decrease the severity of braking, it is enough to unscrew / wrap the drum.
The last brake setting on the bike (point 4) depends a lot on the correct shape of the rim. In the presence of a small figure eight, it is necessary to find the optimal position in which the pads will not wipe the rim. When driving over bumps or holes at high speed, check this setting as often as possible.