Features of bleeding hydraulic brakes on a bicycle
Hydraulic brakes on bicycles have appeared relatively recently, and have already won the sympathy and vocation not only among beginners, but also among experienced cyclists. Such devices are used when high accuracy and reliability are important. Bleeding the hydraulic brakes on a bicycle is carried out when the system has been repaired. Although the mechanism does not have to be repaired often, the time comes when you need to pump the device for its operability.
How to pull
Proceed in the reverse order of loosening the cable and you will get the desired result.
How to adjust disc mechanical brakes on a mountain bike
Mechanics are gradually becoming history. Now it can still be seen in the budget line of Russian Stels, Forward and Stern. Considering the price, there is no need to talk about the belonging of brake system parts to such global brands as Shimano and Sram. Usually this is some kind of noname kit that has a minimum of settings.
Disc Brakes. Basic Adjustment. by Northrock Bikes
Another nail in the list of disadvantages of mechanical disc brakes is that they need to be adjusted more often. This is because one of the pads is motionless. As it is erased, the distance between it and the disc automatically increases. Meanwhile, fluctuations in the values of this gap should be insignificant, otherwise the friction linings will wear unevenly, the quality of deceleration suffers.
Common breakdowns of hydraulic brakes
Hydraulic maintenance is not done as often as mechanical disc devices need it. Before each ride, you do not need to adjust and adjust the hydraulics, which is one of the important advantages. However, along with the advantages, there are also disadvantages that manifest themselves in the form of breakdowns. The most common types of breakdowns are:
- Lever failure when no deceleration effect is observed when the handle is depressed.
- Damage to the hydraulic line, as a result of which it is necessary to replace the hose.
- Pads abrasion.
- Failure of the O-rings. These are special O-rings located on the brake lever (caliper).
- Loss of properties of brake fluid or mineral oil, depending on the type of system.
It is possible to determine the malfunction of the mechanism by such a sign as self-braking of the bicycle. This means that air has entered the system and the expansion springs cannot open the pads from the disc. There are various factors that cause air to enter the system:
- Falling vehicle.
- Low amount of fluid or oil in the system.
- Opening the hydraulic circuit.
- Boiling liquid.
If water gets into the hydraulic system, the working piston can jam. It is imperative to expel air from the system, otherwise it will lead to rapid wear of the pads and discs of the brake system. While riding, you will need to adjust the effort, as the pads will rub against the disc. The sound in the form of a squeak will also help to determine the malfunction of the mechanism. If the bike squeaks, then it’s time to adjust the brake mechanism by pumping fluid.
It is interesting! If mechanical brakes have disappeared on the bike, then they can be repaired even in the field, but for the repair and pumping of the hydraulics, you will need not only a garage with tools and materials, but also knowledge of the process.
How to adjust hydraulic brakes on a bike
The process of bleeding the brakes in step-by-step instructions
When the hydraulic brake system is completely repaired, all you need to do is fill in the brake fluid and then pump it over. Bleeding is needed in order to remove all air from the system, which is an obstacle to the correct operation of the mechanism.
There are several options for pumping hydraulics on a bicycle. Let’s describe the simplest version of how the hydraulic brakes of a bicycle are pumped. First, make sure you have the following tools and materials:
- The tube is transparent, which will fit the diameter of the bleed bolt.
- Brake fluid or oil, depending on the pumped type of system. for Shimano this is a special oil.
- Allen key or sprocket for loosening the bolt on a device with a master cylinder.
- Two syringes.
- Cloth for cleanliness during work.
- The upper bolt on the brake lever. caliper is unscrewed. To prevent oil from leaking out of the cylinder, the mechanism must be moved 5-10 degrees to the upper position.
- After unscrewing the bolt, you need to remove the rubber ring (sealing).
- You need to firmly install a suitable size tube into the hole, and connect a syringe or a plastic bottle on the other side of it (it is better to use 200 ml syringes). This container will be used to collect the expelled oil from the system along with air.
- Now you need to take another 200 ml syringe with a tube and fill it with new oil or liquid.
- Air must be expelled from the syringe with a tube, after which the free end of the tube must be connected to the pumping connection provided by the system on the brake caliper.
- After the tube is tightly put on, you need to unscrew a little bolt for bleeding. Now you need to slowly inject liquid into the system from a syringe, and observe its exit into the container that was originally installed in the mechanism on the steering wheel.
When bleeding the brakes, it is also recommended to tap the brake hose to accelerate the release of air bubbles upward. After bleeding the system, you must first tighten the bolt on the caliper, then remove the syringe with the hose. Before disconnecting the container connected to the master cylinder on the steering wheel, you must first pour the displaced fluid into another container or install the handle, while creating a vacuum. After that, you can disconnect the syringe, install the O-ring, and tighten the fixing bolt.
As you can see, the process does not present any difficulties, and can be done by hand at home. This method is considered to be the simplest and most effective. Remember to remove oil and fluid spills with a clean piece of cloth.
How to Adjust Disc Brakes on a Bicycle: Techniques for Hydraulics and Mechanics
Normally, the disc brake stops the wheel as quickly as possible, allowing the force to be dosed on the verge of blocking the rotor. Deviations appear after replacing the cable, pads and overhaul. However, the settings are violated during long-term use, as well as after removing the wheel, for example, to seal the bicycle camera at home. How to avoid the famous shuffling of the rotor, how to eliminate the braking, and, in the end, how to restore the factory braking character. these and other questions are answered by the editorial staff of Autobann magazine.
Adjusting the brake lever travel
This adjustment allows you to adjust the position of the handle when the brake engages. There are no specific recommendations on this matter. Someone is more comfortable for the bike to brake at the slightest push on the handle, someone more like the presence of a small idle and a dead grip in the middle of the lever path.
This adjustment is carried out using a screw located in the brake lever housing. The final adjustment of the severity of the brake seizure is made by the cable tension thumbscrew.
Attention! After completing all adjustments, check that the pads are equidistant from the rotor. It is possible that the fixed friction lining will have to be readjusted.
Check the pads
We remove the brake pads. To do this, we find the extension on the caliper and turn each block in turn by the tongue. If everything is done correctly, then it will not be difficult to dismantle them. Next, we make a visual inspection of the surface for chips. In case of severe damage or wear, the pad should be replaced.
Safety comes first! Yes, this rule is worth remembering every time you want to ride a bike. After all, many “ordinary” walks end in injuries. “And the cyclists themselves are most often to blame for the accident. It is their inattention that leads to dire consequences. Inattention. what can we mean by this? First, a disdainful attitude towards the object of the ride itself, namely the bike itself. Its malfunction is often the reason for unwanted injuries.
Braking system characteristics
The following terms are used to qualitatively describe the operation of rim brakes:
- impact force;
- wear resistance;
- service requirements;
- comparative features.
Force of impact, or braking, is a parameter that shows how much the brake can clamp the rim so that the bike cannot be moved. Maximum effort is only required to completely stop and lock in place. On the road, the effort is not fully used to adjust the speed. The range of action on the wheel rim by pressing the handle is called modulation, or accuracy, of the brakes.
An active cyclist uses his transport not only in dry and cloudless weather. Rain, mud, sand. everyone who rolls out their bike on long trips will have to face this. The effectiveness of brakes allows you to describe their behavior in a wide variety of conditions.
Durability is a measure of durability, taking into account the prescriptions for the use of the bicycle as a whole. Timely maintenance can increase the service life of the braking system. Service Requirements provide guidance on how to properly install and adjust the machine, how often to do this, and guidance on how to replace parts.
Disc hydraulic brake
So, the winner of the rating. It is hydraulics that rules the world of brakes. How does this system work? There are handles, there is a disc and there are braking elements. They are connected together by rubber tubes, inside of which there is oil, or, as it should be correctly said, brake fluid. What are its pros and cons? The hydraulics are responsive to every pressure. It can be said that it instantly transmits pressure. That is why many athletes and extreme sportsmen use hydraulic disc brakes on their bikes. After all, the accurate transmission of sensations helps to win important seconds. The hydraulic brake firmly compresses the metal disc so that when pressed firmly, the rider can fly out of the saddle in the truest sense of the word. But, like everyone else, hydraulics have their negative sides.
First, the high cost. This, of course, is a dubious minus, because this system is bought not by ordinary amateurs, but by professionals. Second, the fix issue. Yes, the hydraulics simply cannot be repaired by yourself. The slightest upset. and a trip to the workshop is assured. And again, repairs will cost a pretty penny. Parts of the system, such as tubes, are not very reliable. If this part bursts, the brake fluid will leak out. Therefore, you can only brake with your feet. Adjusting hydraulic brakes on a bicycle is tricky. If possible, it is better to entrust this to the master.
Varieties of rim brakes
Rim brakes are divided into several types:
How To Adjust Mechanical Disc Brakes | Halfords UK
- V-brake (vector mechanical);
- hydraulically driven.
Caliper brakes. previously popular modifications, are now rare on the market. They are a classic model of rim brakes with attachment to the fork or stays of the bicycle frame. Design features and operating principle:
- Consist of a handle, a drive cable, two movable bows and brake pads.
- The handle is attached to the handlebars of the bicycle, a cable is pulled from it and fixed on the clamping side of the arches. The body itself is attached strictly above the wheel, pads are screwed to the lower mounts of the arcs.
- Through the cable, the force is directly transmitted to the clamping part of the arcs, due to which they are compressed, and the pads are in contact with the rim.
- Responsible for unclamping is an elastic metal insert or spring built between the levers.
The levers have a single axis of rotation and move towards each other like pliers pincers. Hence the name. tick-borne. Advantages. ease of installation, simple setup. Cons. weak braking force, low modulation, high abrasion of the pads, require frequent debugging. Fits on road racing bikes and optionally as a front rim brake on road models.
Cantilevers belong to the second type of disappearing brakes. The principle of their work is to extend the levers under the action of a taut leash. The principle of operation of the cantilever brake:
- Through the main cable, the force is transmitted to the jumper.
- The cable pulls the jumper up, the leash attached to it is pulled.
- The leash connects both levers, which are rigidly attached to the frame.
- Due to the convergence of the levers, the pads approach the rim.
The cantilevers are dirt resistant, will not bump the tire and are easy to install. Significant disadvantages include:
- decrease in braking force as the leash is pulled;
- you need to create a high effort to stop the bike completely;
- difficulty of adjustment.
In justification of the latter, it should be noted that the position of the pads can be adjusted within wide limits.
V-brake is a common type of rim brake on high-speed bicycles. Compared to cantilevers, it has a higher precision and longer shoe longevity. They are also easy to remove and repair yourself.
The vectors are partially similar in design to cantilevers: the front brake levers are bolted to the fork, the rear brake levers are attached to the upper stays. The legs are connected to each other by a pulling cable. The drive cable is brought to one side, but due to the straight shape of the “tie” forces are equally transmitted to both levers.
Hydraulic bicycle rim brakes are a more advanced mechanical model. The drive system consists of a control cylinder, a hydraulic line and power cylinders. The forces from the handle are transmitted to the master cylinder, which, through the oil, acts on the power cylinders. Those, in turn, move the pads towards each other.
Advantages. high compression force and efficiency, excellent modulation. Disadvantages. deterioration of work with a blockage of the hydraulic line, complex repairs. Used a similar type of brakes for freeride and trial.
Rim-type brakes have low brake pad travel, which means they wear less during operation. A significant disadvantage of this approach is the inability to be used on wheels, even with minor rim curvatures. Sensitive brakes will rub against the wheel on the fly, causing reduced speed and increased pad wear.
How to properly adjust the steering wheel, steering block and stem.
If you have problems with a bicycle handlebar, steering block or stem, it is better to entrust bicycle repairs to trusted specialists of the VeloTemp bicycle workshop, who guarantee the quality of the work performed and a conscientious attitude. They will also check how the steering system is tuned, test the degree of tension of these elements. To adjust the functioning of parts, specialists cannot do without a hexagon. You should also exclude the presence of backlash, and if it is detected, you need to urgently take measures to eliminate the problem that has arisen. Do not forget that the steering wheel should also be adjusted from time to time. This process involves clamping the steering wheel with special wrenches. Make sure the handlebar is tight enough so that only experienced technicians will fully and accurately repair your bike without damaging its mechanisms. Modern bicycles are expensive enough to risk doing repairs yourself.
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.