Hydraulic bike brakes
Hydraulic brakes. fluid hose instead of cable
The mechanism of action of hydraulic brakes is very similar to that of their mechanical counterparts (disc and rim brakes). The main difference is that mechanical brakes use bicycle cables, while hydraulic brakes use a special hydraulic line instead of a cable. This hydraulic line connects the brake levers to the brake itself, which can be a mechanical disc or V-brake pads.
- Advantages and disadvantages of hydraulic brakes, their application
- Installation of hydraulic brakes
- Bleeding hydraulic brakes
- Adjusting the hydraulic brake pads
- Video. What are the front brakes for
The bottom line is that there is oil or brake fluid under pressure in the hydraulic line. There are cylinders at both ends of the hose. When you press the brake lever, the brake cylinder transmits force to the brake line, which activates the other cylinder at the other end of the tube, which in turn activates either the rim or disc brake, whichever you use. If you use brake fluid inside the tube, you must take into account the fact that this fluid is poisonous and to paint coatings (corrosive). Therefore, this liquid can be replaced with oil.
Advantages and disadvantages of hydraulic brakes, their application
The main advantage, in fact, which prompts the owners of hydraulics to use it, is the accuracy of the braking performance, its clarity and responsiveness. With prolonged use of mechanical brakes, either the brake pads are worn out, or the cables wear out (sometimes break). Using hydraulic brakes will not present you with this problem. The main thing here is to prevent kinks of the tube in which the brake fluid is located, well, with a damaged tube, you can, accordingly, be left without brakes at all. The rest of the hydraulics is at a high level and there should definitely be a future behind it.
Since the use of hydraulics makes the brakes feel better and makes them act more clearly, they are very often used on powerful bicycles. For example, on bicycles intended for freeride or trial. For bicycles that are used in extreme conditions, where the speed of the bicycle’s reaction to braking is one of the main selection criteria.
The disadvantages include the complexity of the repair. For example, in the field, a punctured hydraulic line can become a significant problem for you, which will be quite difficult to eliminate. If this happens during the race for the winner, there is a big chance that you will be the last one. Some more disadvantages lie in the fact that there are difficulties in installing the trunk, since the brake line can become an obstacle in this. Difficulties in removing and putting on wheels on forks. you need to be very careful so as not to accidentally damage the brake pipe.
Installation of hydraulic brakes
To apply the rear brake to the frame, the brake hose must be disconnected because the brake hose will need to be threaded through the mount. Usually the hose is simply attached to the frame. Remove the pads before working on hydraulic disc brakes, as the brake fluid will spill and dirty. Make sure you have clean hands before starting. Remove the pads, move the discs and pads away from the bike and then you can disconnect the brake line and pass it through the frame again, connect and pump the system.
Cam and compression brass fitting with nut.
Disconnect the hydraulic hose from the discs and pads. Keep them away from the work area. When the hose is pulled out, the brake fluid may become contaminated. So, if you now bring the end of the hose closer and take a closer look, you can see the cam and the compression fitting. The brass fitting is used to prevent the plastic hose from shrinking from the heat and from jumping out of the cam when the system is very hot, that is, the cam and the fitting simultaneously hold the hose in place when it heats up.
Before threading the brake hose into the mount, make sure the gasket fits your bike. Fork manufacturers today require the hose not to rub against the crown or the leg of the forks otherwise they will void the warranty. Do not leave the hose too long so that it does not touch the crown or it could damage it with constant friction. Pull it up carefully, but so that the steering wheel does not break the hose at maximum turns. Pull along the frame, through the holes, straight to the mount, and from there outward to the clipper. Now you can attach the car to the frame.
Now we need to cut the hose, leaving a small loop. Remember that the hose is inserted into the machine, so do not cut it too short at the very entrance to the machine body. It is necessary to add 7-10 millimeters to the length. When you have cut the hose, you can put in a new olive and compression fitting. First, we put on the nut that holds them, then the clamp. There are directional clamps, so it is very important to read the manufacturer’s instructions for your particular disc brake system. Some clamps have a chamfer. When the clamp is on, insert the compression fitting. It should fit snugly and clamps should be used to hold the hose firmly without damaging it. Then take a hammer and drive in the fitting. When the fitting is in place and the clamp is ready, put the nut on, lightly lubricating the clamp and nut so that everything fits into place. Tighten it by hand and when you think that it will stop push the hose all the way into the machine, now you can tighten the nut and again try not to overtighten, it is better to use a special tori wrench. To tighten the compression nut to the desired value.
If the nut is tightened properly, you can start pumping.
- Read everything you want to know about bicycle braking systems in this article.
- Find out why the roller brake is ideally modulated and who is best for you
Bleeding hydraulic brakes
When bleeding the disc brake system, keep the discs and pads away. First of all, unscrew the master cylinder and fasten it again so that the top of the cylinder is horizontal. Since we will inject liquid into the system, it is better to work with a flat surface. Now you need to remove the top cover from the master cylinder. Most likely it is secured with Phillips screwdriver screws. Make sure the head of the screwdriver is sharp. Some screwdrivers are thorium-coated. As with everything, it is important to use the right tool in your work. like with a girl.
By unscrewing the master cylinder cover, you can see the master cylinder membrane. It expands and contracts as the temperature of the brake fluid changes. Under it you can see the brake fluid. It must be emphasized that you must use fluid for your disc brake system. If the fluid is not the right one, you run the risk of serious injury due to inoperative brakes. But most importantly, you can damage the entire brake system, and its repair is very expensive.
Tools that you need for pumping.
Each disc brake system can be pumped differently. Read the manufacturer’s instructions. You can use your own methods, but be extra careful and be sure to check the brakes before riding. Here we will consider pumping the shimano system. A special tool is used for it, which is attached to the main cylinder body. Liquid is collected in its bottle, it can be hung on the handle. It looks like a bottle with a tube extending from its cap, which adapts to the brake system. When we pump liquid from the pad through the system with a syringe, it will pass through the master cylinder into the tube. There is a small hole at the bend of the tube with a tube and the liquid will flow into the bottle.
Now you need to draw the liquid into the syringe. It uses a Shimano disc brake fluid bottle with a mineral base. I emphasize again that you need to use the correct fluid. Draw liquid into a syringe. To bleed the brake system, you need to dial as much as possible. If you get air bubbles in the syringe, flush them back into the bottle so that no air remains in the syringe, otherwise you will not reach your goal. You bleed the system in order to get rid of air in it and fill it 100% with brake fluid.
Now you need to inject the liquid through the machine. When you inject fluid through a typewriter, it can immediately open the piston valve and there is a possibility that the valve will pop out of the body, so many disc brake manufacturers include a gasket with them, which, when pumping, can be placed where the pads are usually located. If the gasket does not fit your brakes, you can use a spare brake lever and something else that will prevent the valves from coming out of the machine body.
Brake fluid bottle.
Bring fluid to the very end of the hose and slide the hose onto the inlet nipple. Open the inlet nipple with a wrench. You can now supply fluid to the system. Gradually. When pumping fluid through the system, it is important that it does not leak. Some brake fluid compounds can damage paint. The mineral composition is harmless. And with other compositions, I advise you to cover the frame with something to protect the paint from damage. When pumping fluid into the system, tap on the pipes with an assembly wrench or other tool so that air that may remain in the main cylinder body is released. Stop dispensing beforehand. Now close the inlet nipple and you can pick up the tube. Check again that the valves are all recessed into the machine body. The fluid that you pump through the system can now be removed. The fluid should reach the top edge of the master cylinder housing. There should be no air here. Clean the master cylinder diaphragm, if necessary, so that there is no contamination. Put it on top and close the lid.
The disc cleaning fluid can be used to wash off the remaining brake fluid from the steering system, and to clean discs and pads if required. Clean the clipper. It is recommended to use technical napkins that do not give lint. If you use an old rag, it will leave a lot of small particles, fluff, which will get into the brakes and can cause leakage or dirt.
Be sure to wash your hands before installing the pads in the system. You have pumped the brake system and most likely you have brake fluid residues on your hands. You don’t want to get the pads dirty by inserting them into the brake system. When working with the brakes, your hands must be clean, as oil, grease, brake fluid will contaminate them and you will need new pads. As you know these disc brake pads can be expensive.
Adjusting the hydraulic brake pads
If you have correctly adjusted the machine and the brake disc is exactly in the center, but still clings to the pads, this usually means that one of the valves protrudes from the body more than the other. Once you are confident that the disc is exactly in the center of the clipper you can do one trick to even out the distance between the pad and flange. It will take two people. One should press the disc against the valve, which is too protruding, and the other will work with the pads, sliding and extending them. The valves will align. Due to the pressure of the disc, one valve works more than the other, that is, with the help of the disc, we press one valve into the body, while the second moves further. This is how we align the valves using a disc. But don’t push the disc too hard, you can bend it.
- Bicycle brakes are not a luxury, they are a must. Which brakes you put on your bike will determine the degree of your personal safety while riding.
- Cost for popular hydraulic brake models: www.velosipedinfo.ru/diskovyie-tormoza
I want to say that using hydraulic brakes, if the speed of the bike is high enough, you need to be extremely careful so that it does not work out as on
Which brake fluid is best
The answer to the question of which brake fluid is better depends on the requirements that are imposed on it by the automaker (there are always instructions on what to pour in the manual), its characteristics and classification.
Most brake fluids can be categorized by performance, DOT classification, and specific manufacturers and brands. Some car manufacturers suggest the use of a fluid with a specific specification in the brake system, although in most cases it is similar to that suggested by DOT-4.
In this connection, if a dilemma arises of which brake fluid to choose, then it concerns the fluid that belongs to the DOT 4 class. To figure out what to fill will help the rating of fluids, which includes 4 foreign manufacturers and 4 domestic ones, which are worthy competition.
|Imported brake fluids|
|Castrol React DOT4 Low Temp||The best indicators for cleaning power and boiling / freezing point. Can be used in any geographic latitude.||0.5||520|
|Liqui Moly Bremsenflussigkeit DOT4||The composition contains anti-corrosion additives that extend the life of the rubber elements. It has insufficient boiling points, up to 230 ° C and a mediocre low-temperature viscosity, as much as 1800 mm 2 / s. Not recommended for northern regions.||1.0||700|
|Mobil Brake Fluid DOT 4||Possesses optimal viscosity and stability. Withstands temperatures down to. 30 ° C without loss of viscosity.||1.0||570|
|Domestic brake fluids|
|Sintec Euro DOT 6||Has characteristics similar to DOT 5.1, Highest boiling point 274 ° C. Excellent kinematic viscosity, suitable for northern latitudes.||0.9||450|
|ROSDOT 6 DOT 4 (class 6)||It has the best indicators of kinematic viscosity among domestic TZ. 697.5 mm 2 / s. Exceeds the requirements of liquids of class DOT 4 regarding boiling point. 260 ° C. Low price.||0.91||350|
|Sintec Super DOT 4||Made entirely of synthetic base and suitable for use in any conditions, which however has mediocre stability, although the boiling point is quite high. 270 ° C.||0.91||250|
|Lukoil DOT 4||High boiling points, however, the viscosity at low temperatures is quite high. Very popular due to marketing promotion, because it fits into the requirements of DOT-4.||0.45 and 0.91||140; 250|
|Hi-Gear DOT 4||Confident average, produced under license. It has a high boiling point, but low-temperature viscosity has pumped up. For severe frosts, it is better not to use.||0.47||260|
|ROSDOT 4||Fully synthetic fluid, but with poor performance. For the north and cars with ABS is categorically not recommended!||0.45 and 0.9||240; 350|
|Sibiria Super DOT 4||It has the worst temperature ratings on the list, but is quite suitable for use in mid-latitudes. Has good cleaning ability and low cost.||0.45||140|
To understand the question of which brake fluid to pour, study the basic characteristics inherent in a particular TJ. So, brake fluid must be selected according to the following criteria:
- Viscosity. A fluid with a high viscosity (thick) in the cold thickens even more and can poorly transfer forces to the braking system. And a composition with a low viscosity can often leak out of the system little by little, because of which the motorist will have to regularly add it there. Accordingly, it is advisable to use a thicker brake fluid in the southern regions of the country, where there are no significant frosts, and a less dense composition in the northern ones. Although the temperature range is directly indicated in the description on the packaging of this or that “brake”.
- Boiling temperature. When heated and boiled, air is released in the liquid, which leads to airing of the brake system, and a decrease in its effectiveness up to a complete failure. Accordingly, the higher the boiling point of the brake fluid, the better. But it is important that this characteristic does not decrease the boundary value after a year of operation.
- Freezing temperature. Here the situation is the opposite. In severe frost, the fluid can thicken strongly and not transfer the forces from the pedal to the performing elements of the brake system. The result is obvious. partial or complete brake failure. Therefore, for residents of the northern regions, you should always choose a brake fluid with a low freezing point.
- Chemical neutrality, inertness. “Tormozuha” ideally should have, firstly, anti-corrosion properties, and secondly, not to corrode rubber pipes and other elements that make up the brake system.
- Lubricating properties. The fluid should not only not harm the parts of the brake system, but also protect them from exposure to moisture from the air.
- Hygroscopicity. This is the property of the brake fluid to absorb water from the surrounding air. It should be as low as possible, because otherwise, when there is a lot of moisture in the liquid, its performance properties are sharply reduced. In particular, the freezing point rises and the boiling point decreases.
The above characteristics are directly or indirectly indicated by the manufacturer on the product packaging, which provides most of the information to answer the question of which one is better to fill in brake fluid. However, there are a few more nuances that must also be considered.
Brake fluid base
All modern fluids are made on one of three basic formulations. glycol, polyglycol and silicone. The first two types are most common. With the help of additional additives, manufacturers can regulate their boiling and freezing points within the required limits (depending on the specific fluid and brand). However, their disadvantage lies in their relatively high hygroscopicity, which is why such brake fluids need to be replaced with new ones approximately every two years.
Silicone-based brakes have excellent performance characteristics. In particular, they are completely non-hygroscopic, have a high boiling point, and practically do not shrink. However, there were also some drawbacks. In addition to the high price, such liquids (DOT-5) cannot be used in a car with ABS. Accordingly, they are used in sports cars or in cars where prescribed by the manufacturer.
DOT Fluid Classification
The technical documentation of any car directly indicates what standard fluids are allowed to be used for this car. It is impossible to deviate from the requirements. Mixing some fluids, but not all (.) Is allowed but not recommended. Description of DOT standards:
- DOT 3. This is the oldest class still found on the market. The fluids are made on a glycol basis. In accordance with the standard, the boiling point of a “dry” (without moisture) liquid is at least 205 ° C. And “wet” (up to 3.5% moisture). not less than 140 ° C. The replacement period for this class of fluid is two years.
- DOT 4. Similarly, they have a glycol base, but their composition has been improved by the use of additional additives designed to improve lubricating properties and protect against corrosion. In accordance with the standard, the boiling point of the “dry” liquid DOT 4 is not less than 230 ° С, and the boiling point of the “humidified” one is not less than 155 ° С. Viscosity requirements are also evenly limited. 750. 1800 mm2 / s.
- DOT 4.5, DOT 4, DOT 4 SUPER, DOT 6. These subclasses are rather a marketing ploy of individual manufacturers who add additional additive packages to standard DOT 4 fluids to improve their performance. There is no uniform requirement here, but in any case, they will not be worse than DOT 4 liquids, and sometimes slightly exceed them.
- DOT 5.1. Such a liquid is a technological continuation of the DOT 4 class, in particular, in terms of an extended temperature range and protective qualities. These brake fluids are also glycol based. However, they have a significant drawback. they are very hygroscopic. And given their relatively high price, they did not find the necessary popularity.
- DOT 5. The class of brake fluids is closest to ideal parameters, since their base is made on the basis of silicones. Accordingly, they are completely non-hygroscopic (do not absorb moisture), have a very wide temperature range (according to the standard, the boiling point of a “dry” liquid is 260 ° C, and a “wet” one. 180 ° C), and the replacement period is increased to 5 years. The use of such a liquid is permissible only at the request of the automaker, since there are a number of operating features
How to choose brake fluid
The best choice of foreign-made brake fluids. Castrol React DOT4 Low Temp
Castrol React DOT4 Low Temp brake fluid significantly exceeds the declared standard in its characteristics. So, its boiling point is 265 ° С (fresh liquid), and “wet” (after a year of operation). 175 ° С. Accordingly, it can be used during high-speed driving and frequent hard braking. And even the replacement interval every 2 years will be more than enough.
The Low Temp prefix in the name indicates that the liquid has a very low kinematic viscosity at a temperature of 40 ° C, equal to 650 mm² / s. This is especially true for vehicles equipped with ABS. It is thanks to its characteristics that the Castrol brake fluid gets its first place.
Liqui Moly Bremsenflussigkeit DOT4
Fully synthetic brake fluid Liqui Moly Bremsenflussigkeit DOT4. Its boiling point is 260 ° C for the “dry” composition, and 155 ° C for the “humid” one (after a year of service). As for the kinematic viscosity at 40 ° C, it is 1800 mm? / S, this is the boundary permissible norm. Accordingly, this liquid can be fully recommended for use in cars with ABS in mid and southern latitudes, but it is hardly worth using in such cars in latitudes with significant frosts.
Meets the requirements: SAE J 1703, J 1704, ISO 4925, FMVSS 571.116 DOT 4. The main emphasis of the Liquid Moli brake fluid is made on lubricating, anti-corrosion and protective properties. If you have measured driving, then this TJ is just for you.
You can buy Liqui Moly Bremsenflussigkeit DOT4 brake fluid in 250 ml and 1 liter canisters.
Mobil Brake Fluid DOT 4
Mobil Brake Fluid DOT 4 brake fluid has slightly lower characteristics in relation to temperature operating conditions. The boiling point of the “dry” liquid is 263 ° C, and the boiling point of the “humid” one is 168 ° C. The value of the kinematic viscosity at a temperature of 40 ° C is 1200 mm? / S.
With a stretch, it is suitable for use in cars in northern latitudes, since the boundary lower operating temperature without loss of performance reaches only 30 degrees Celsius. Depending on the packaging and specifications, it can be designed to work in cars equipped with ABS and ESP systems. Possesses good protective properties. It is recommended to change it every two years of operation or after 40 thousand kilometers. Can be used in vehicles where certification compliance is required: FMVSS 116 DOT 4, SAE J1704, ISO 4925.
Unlike the leader Castrol, Mobile packs its TJ not only in 0.5 liter canisters, but also 1 liter.
The best domestic brake fluids. Sintec Euro DOT 6
In the designation of Sintec Euro DOT 6, the last DOT 6 symbols are the aforementioned marketing ploy, since this is how the DOT 4 class is denoted on the territory of the Russian Federation, or simply DOT 4 with improved characteristics. However, real tests of the liquid have shown that it really has quite impressive performance. Thus, its boiling point in the “dry” form is 274 ° C, and in the “wet”. 182 ° C. As for the kinematic viscosity, at 40 ° C it is 647.5 mm² / s. Accordingly, it is quite possible to recommend it for use in any northern latitudes on equipment equipped, including ABS.
Sold in a 900 ml canister. Her
ROSDOT 6 DOT 4
Brake fluid ROSDOT 6 DOT 4 belongs to TJ class 6 because it exceeds the requirements for DOT-4 fluids. Thus, the boiling point in the “dry” state is 260 ° C, and in the “humid” state. 168 ° C. Kinematic viscosity in frost is 697.5 mm² / s.
In addition to temperature and viscosity indicators, the main advantage is the low price. Therefore, Rosdot brake fluid is one of the leaders in the rating.
Sintec Super DOT 4
Sintec Super DOT 4 brake fluid performed well in high-temperature tests. The boiling point of the “dry” composition is 270 ° C, and the “humid” one. 173 ° C. But at low temperatures it does not behave in the best way, the kinematic viscosity at 40 ° C is 1172 mm² / s.
Sold in 910 ml cans.
Lukoil DOT 4
Brake fluid “Lukoil DOT 4” is a confident “average” among domestic products. It may well be recommended to car owners living in various, including the northern regions of the Russian Federation. So, the boiling point of the “dry” composition is 270 ° C, and the “humid” one. 176 ° C. The value of “cold” kinematic viscosity is 1170 mm² / s. Meets only two requirements: FMVSS 116 DOT 4 and SAE J 1704.
Hi-Gear DOT 4
Hi-Gear DOT 4 brake fluid has a reduced hygroscopicity. It also belongs to the “average” rating, as it is produced under license. Has similar “dry” and “wet” boiling temperatures. 270 ° С and 174 ° С, respectively (after a year of operation). The value of “cold” kinematic viscosity is also quite good, and amounts to 1193 mm² / s. Therefore, it can be used in the northern regions of the country, but without the ABS or ESP system.
The Hi-Gear brake fluid can be found on sale in a small 473 ml canister at a price of 260 rubles.
The ROSDOT 4 brake fluid is completely synthetic based. As for its operational characteristics, they can rather be called mediocre. And if the protective (cleaning) properties are at an acceptable level, then the temperature is below average.
So, the boiling value of “dry” and “wet” composition is 259 ° С and 159 ° С, respectively. But the value of the kinematic viscosity is the worst in the list. 1678 mm² / s. Therefore, Rosdot 4 brake fluid is not recommended for use in northern latitudes, only in temperate and southern ones. TZ RosDot 4 is a good choice for domestic cars that do not have additional stabilization and braking systems.
On sale can be found in canisters of two volumes. 450 ml and 900 ml. Their are 240 rubles and 350 rubles.
Sibiria Super DOT 4
Sibiria Super DOT 4 brake fluid has the worst temperature performance. So, its “dry” composition boils at a temperature of 254 ° С, and its “wet” one. 160 ° С. The value of the kinematic viscosity is 1415 mm² / s. These indicators meet the DOT requirements, but nothing more. However, the cleansing ability is quite good. Sold in a small container, which is not always convenient when replacing. Not recommended for use in northern latitudes.
Sold in a 455 ml canister, medium
Usually, imported manufacturers produce better brake fluids with better performance. However, their price is higher. Conversely, domestic samples are more attractive in terms of cost, but have worse performance. Therefore, the general recommendation is this: for new cars with low mileage, it is better to use better quality imported samples. And accordingly, for budget cars with high mileage, you can save money. The main thing is to change the “brakes” according to the regulations specified in the documentation for the car.
As of the summer of 2020 (in comparison with 2019), among foreign brake fluids, Castrol (0.5 liter capacity for 150 rubles) and Mobil (a liter package for 110 rubles) rose the most, and Liqui Moly remained at the same level.
There were practically no changes in among the domestic funds presented in the rating for the indicated period. But Hi-Gear DOT 4 and ROSDOT 4 (in 0.91 l capacity) became a little cheaper, on average by 50 rubles.
Which bike brakes are better. disc or rim
Which brakes to choose a bike. disc or rim? This question is relevant when buying a new bike. There are many models on the market, and each one has its own braking system. Actually, the standard division of brakes is simple. V-brakes and discs (cantilevers, pliers and drums are noticeably a thing of the past). V-brakes are presented by mechanics, disc brakes. by mechanical and hydraulic modifications. To better understand which of them to focus on, we will consider separately the types of modern brakes, their advantages and disadvantages.
V-brakes rim brakes: overview, advantages and disadvantages
Rim brakes act directly on the rim surfaces to slow down rim rotation. The handles are located on the handlebars and the hold-down mechanisms are located directly next to the wheels. All this is connected by a cable, through which the efforts from pressing the handle are transmitted.
Such an uncomplicated design at one time cranked a revolution in the field of bicycle brakes, replacing cantilevers, drums, rollers and pliers. V-brakes are still in demand today. A good half of road bikes, MTBs, hybrids and sports models are equipped with them. They have earned their popularity thanks to a complex of advantages. Not without its drawbacks. Let’s consider each of them in more detail.
Positive aspects of rim brakes:
- low cost of components;
- light weight;
- maintainability in travel and at home;
- high braking force.
The v-break brake can be easily repositioned on the frame of any bike where there are seats for levers. There are no special requirements for installation on a specific model, therefore budget and expensive brakes are interchangeable.
The overall weight has a noticeable effect on driving dynamics. Rim mechanisms will not affect the bike’s lightness. They are great where speed and acceleration play a big role: racing, driving on highways and city roads.
The simplicity of the mechanism and versatility provide a new positive quality. maintainability. Installing the spare part and adjusting the rim brakes are intuitive, so you can do it yourself.
Compared to cantilever and caliper counterparts, V-brakes grip the rims “tightly”, providing safety in case of emergency. By the strength of the impact, high-quality and carefully tuned mechanisms successfully keep the brand in front of the disks.
Disadvantages of rim brakes:
- low modulation;
- sensitivity to curvature of the rim;
- deterioration of work in mud and wet weather;
- abrasion of pads and rims, heating with prolonged braking.
Modulation, or handle pressure sensitivity, is the most important technical indicator of brakes and shows to what extent the speed of a bicycle can be reduced. V-brakes are superior in this respect to their “older” brothers, but noticeably inferior to discs. Of course, the cost of the model also matters. Expensive Shimano or Avid will have higher accuracy. On budget brakes, this disadvantage can be slightly reduced by more careful tuning.
Eights for rim brakes are not permitted. Otherwise, the bike will constantly slow down, and during acceleration, you can wear out the pads or break the distance between them. In addition, curvature of the rim surface reduces braking force. So owners of bikes with vi-breaks should always check the wheel geometry and correct its deficiencies in time.
Dirt, water, ice and even oil accidentally hitting the rim are the main enemies of these brakes. Adding clay will completely remove the brake from working condition, and water can reduce the braking efficiency by almost half. The same thing happens with other materials like oil. Cyclists are advised to carry a brush and soft dry cloth at all times to clean the surface of the wheel and pads.
Long-term use of the rim brake does not go unnoticed either on the pads or on the wheels themselves. This means that over time, along with the decks, the rims themselves will have to be changed. Prolonged braking is negatively reflected in the condition of the pads, strength and geometry of the wheel. In combination with other factors (sand, abrasive, small stones), wear can increase several times, shortening the life of both brakes and wheels.
Pros and cons of disc brakes
The disc braking system is a progressive step forward even in comparison with the most expensive V-brakes. Disc brakes on a bicycle work in a similar way to car brakes: the force from the handle is transmitted through the drive to the caliper. The brake pad, pressing against the disc, slows down the rotation of the wheel. The disc itself is fixed in the center of the wheel and rotates synchronously with it.
Discs. the ability to eliminate wheel rim wear and provide better braking. At least in these two parameters, they should be 100% better than the rims, but let’s look at everything in order.
Strengths of disks:
- no wear or overheating of the rim;
- indifferent to eights;
- can be used in harsh conditions;
- clear modulation;
- longer service life.
When the bike decelerates, heat energy is not transferred to the wheel chassis, but to the disc rotor. Wheels do not heat up, therefore, they are less likely to damage them during long periods of braking.
Since a separate surface is involved in braking, there is no need to talk about any surprises associated with wheel curvatures. Of course, riding in eights is still a pleasure, but this does not affect the effectiveness of a stop.
Disc brakes handle dirt well. The resistance to water is slightly lower, but better than that of rims. The braking surface is not solid, so water is well drained through the slots. As for accidentally falling grease, it is better to wipe it off thoroughly from the discs.
Even basic discs have such a high modulation that even the most advanced rim models cannot provide. A light push on the handle will easily adjust the speed of the bike without stopping it completely. Modulation is stable and does not require constant system tuning.
The pads and the discs themselves will serve several seasons of active riding without any problems, which cannot be said about the rim counterparts. Here is such an attractive set of advantages, but here too it was not without negative points.
- high cost of the system and individual components;
- no versatility in installation;
- DIY repair is often impossible;
- big gain.
The negative features of discs are diametrically opposed to those of rim brakes. Budget bikes will not be equipped with a disc system, simple v-brakes will be installed there. Each of the manufacturers of rims individually approaches their design and installation on a bicycle, so it is unlikely that it will be possible to “throw off” the system from one bike and put it on another. If you decide to change the rim brakes to discs, there will also be a failure. lack of a seat. True, some models still provide for the installation of both, but this is an exception.
It is more difficult to repair disc brakes; in the field, you cannot do without a special puller tool at all. Compared to the v-brake, there is a good gain in total weight, plus a mechanical effect on the wheel hubs.
Disc brakes with mechanics and hydraulics
By the type of drive, the system is divided into mechanical and hydraulic. The first type of brakes has a standard cable drive. Its main features:
- the efforts from the handle are transmitted to the cable;
- the cable is pulled up;
- the brake pad moves in the caliper;
- under the action of the return spring, it bounces off the disc when the lever is released.
Over time, the cable in the jacket springs and lengthens, which leads to a weakening of the braking performance. Within reasonable limits, this problem is solved by tightening the adjusting screws, they also adjust the position of the pads relative to the disc. Atypical, but there is overheating on the mechanics. Parts must be lubricated periodically to avoid additional friction. The braking surfaces must always be kept clean. Mechanics are simpler than hydraulics in self-repair and cheaper.
The hydraulics mechanism is more complex and consists of the following elements:
- a reservoir with brake fluid or oil;
- leading drive cylinder;
- brake pistons.
When you push down on the brake lever, the fluid compresses and forces the power pistons to move. They, in turn, transfer efforts to the pads.
Advantages over mechanics: softer pad travel, durability of the hydraulic line, better modulation, no backlash. However, hydraulics are more difficult to maintain and require qualified adjustments.
- Mechanical disc brakes are cheaper and simpler, so they are suitable for those who choose a budget bike model.
- Hydraulic brakes require a specialized workshop for repairing the hydraulic line, bleeding, replacing components. It makes sense to take them when the workshop is nearby in order to turn there for help.
- Hydraulics are best used in particularly tough conditions where power, accuracy and braking speed are at the forefront.
Which brakes are better. rim or disc. depends on the cost, purpose of the bike and operating conditions. On budget models, rim brakes are installed, on more expensive ones. disc brakes. Super-fancy bikes are equipped with a hydraulic system. Where extreme is excluded and speed is important, V-brakes are suitable, for non-standard trips it is safer to buy a bicycle with disc brakes.
Adjusting and bleeding hydraulic bike brakes
Hydraulic brakes are used primarily on bicycles where precision, responsiveness and reliability are required. First of all, these are heavy, massive mountain bikes designed to overcome steep slopes and climbs. Also, hydraulics have become an integral part of high-speed bicycles, since it allows you to very accurately and quickly drop speed.
The principle of operation of hydraulic brakes is very similar to mechanical brakes, where the brake pads are driven by a cable. The only difference is that in the hydraulics, instead of cables, brake fluid is used, and levers and eccentrics replace the cylinder-piston groups. Thanks to this approach, the friction forces in the system are significantly reduced, and this increases its service life.
Despite this, hydraulics also has disadvantages, first of all, it is difficult to repair in case of breakdown. For example, if a hydraulic line breaks down, the brakes will not work in the field. The most that is possible with the tools is to bleed the hydraulic brakes.
Hydraulic brake device
Any hydraulic brake consists of at least two cylinders with pistons, connected by a line, or, more simply, a hose that can withstand high pressure. When the cyclist presses the brake lever, the piston displaces the brake fluid from the master cylinder and transfers it to the slave cylinder located in the machine. Here, under the action of pressure, the pistons begin to move forward and press on the brake pads. And already due to the friction of the pads on the rotor (brake disc), braking occurs.
The cylinders in the brake machine are always larger than those in the brake lever. Thanks to this, in accordance with the law of hydraulics, the working brake pistons press on the pads several times more force than the cyclist does by pressing the handle. Also, this law works here due to the fact that two cylinders are installed on the brake machine, or even all 4, 2 on each side.
Symptoms of a hydraulic brake malfunction
The first symptom of a malfunctioning bicycle brake is that it starts to brake on its own. This can be explained by the fact that air has entered the brake system. This could be due to a fall of the bike, a low level of brake fluid in the reservoir, or when the hydraulic circuit opens.
Since air tends to be compressed, unlike liquids, when it enters the system, it works like a gas spring. That is, the air creates the pressure of the brake fluid, which activates the brakes.
Also, the braking system can engage in similar self-activity, in case of jamming of the working piston. And the reason for this is the ingress of water into the hydraulic system.
And, of course, the brakes urgently need to be repaired if the brake lever is not as elastic as before, or the hydraulics no longer responds to the cyclist’s command to stop the vehicle.
Troubleshooting and repair
To understand what exactly happened to the braking system of your faithful two-wheeled friend, you first need to do some experiments. The first step is to remove the wheel where the problem appeared. Next, you need to clean the brake machine well, the easiest way to do this is with a toothbrush. Well, the main goal is to remove the pads.
When access to the working pistons opens, you need to press them in with a screwdriver, and then gently press the brake lever. Both pistons should move forward. If one of them is stuck, you need to use a repair kit to fix the problem. Also, the piston system must be carefully inspected for leaks, if they are present, then the cylinder-piston group is worn out. As a rule, in this case, the pistons or special O-rings on them are changed.
In conclusion, you need to carefully inspect the entire hydraulic line. There should be no kinks, dents or other damage on it. If present, the hose must be changed.
Pumping. the final stage of repair
When the whole system has already been completely sorted out and assembled, it remains only to fill in the brake fluid and properly pump the hydraulics. The system is pumped in order to expel air bubbles from all pipes and cylinders, which prevent the hydraulics from working correctly.
There are a lot of ways how to bleed the hydraulic brakes of a bicycle. Everyone can do this at home, if they know how to handle tools a little. Someone uses syringes, and someone uses old and proven methods. Consider the simplest and most time-tested option.
To bleed the brakes, you will need the following components:
- a transparent tube, suitable in diameter to the bleed bolt;
- brake fluid or oil, depending on the specific system;
- required keys;
- jar or bottle;
- a piece of clean cloth to keep it clean.
First you need to put a transparent hose on the bleeding bolt, and lower its other end into a jar, where there should be some brake fluid. Next, you need to open the brake fluid reservoir on the handle and make sure that it is at the maximum level. If necessary, add liquid.
After that, you can start bleeding the disc brakes on your bike. Pressing the brake lever several times, you need to fix it in the pressed state and at the same time unscrew the screw for bleeding on the brake machine. In this case, you can observe how air bubbles will go out of the tube. After that, the screw must be tightened immediately, and only then you can release the handle and swing again.
This procedure must be repeated several times until the whole system works as it should. This can be felt by the stiffness of the brake lever.
Video showing the pumping procedure:
And one more way to pump the hydraulic line for the lazy:
When repairing hydraulics on a bicycle, it is unacceptable for brake fluid to get on the pads or rotor. If this happens, the elements must be cleaned immediately with fine sandpaper. Otherwise, the brake pads will not work efficiently and quickly fail.
It is also important to know that brake fluid is poisonous and can be harmful to health, so it is not recommended to get it on the skin. Eye contact should be especially avoided. In addition, it is a good solvent. easily corrodes the bulk of paints and varnishes.
The main types of bicycle brakes and their differences from each other
Every novice cyclist soon thinks about upgrading his bike and thinks what to change in the first place, or maybe even switch to new brakes. Here the question arises before him, what kind of brakes are there on bicycles, how they differ and how to choose the ones that are right for his riding style.
Types of brakes on a bicycle by mode of action:
- Cantilever brakes
- Caliper brakes
In rim brakes on a bicycle, the brake shoe is pressed against the rim of the wheel and braking occurs due to this. In disc brakes, braking occurs by pressing the pads against the rotor (disc) of the bicycle. In drum and roller brakes, the brake itself is located inside the hub of the bicycle and braking occurs due to the transfer of force by the cyclist’s legs to the bicycle pedal backward, i.e., we pedal back and stop. This is typical mainly of old models of bicycles (Ukraine, etc.) and is almost never used in modern bicycles (the exception is bicycles with a planetary hub, for example)
By way of transmission of braking force
According to the method of transferring the braking effect to the brake itself (it does not matter whether it will be a disc brake, or a rim brake), bicycle brakes can be divided into:
In both cases, we press down on the brake lever on the bicycle handlebars. If it is a mechanic, then the brake lever is connected to the bicycle brake itself by means of a metal cable and when you press the brake, the cable is stretched pressing the pads against the rim or rotor
In hydraulic brakes, a hydraulic line (tube) filled with oil fluid passes from the brake lever to the brake mechanism. When the brake lever is applied, the brake fluid inside the tube begins to move under pressure and transfers force to the brake, after which the brakes are applied.
In the case of hydraulics, the force transmitted to the brake can be very small, that is, we can brake with almost one finger and do not have to put too much pressure on the brake. In mechanics, the effort must be greater. This will be discussed in more detail below.
Let’s try to figure out what is actually better and why just below.
So let’s get down to a more detailed description of each type of brake and weighing the pros and cons.
Drum bike brakes
|When we press the pedal back, the fitting begins to move along the thread until it stops||When it comes to the stop, it locks the pads and presses them against the glass|
Read about the drum brake device on a bicycle in a separate article. In a nutshell, the principle of a drum brake, or it is also called a foot brake, is as follows. Inside the rear hub of the bicycle wheel there are several parts, 2 pads and one part that has a thread. When the wheel rotates backward, this part is twisted moving another part, which presses the pads against the wheel hub and stops the wheel.
Most often, such bicycle brakes are used in older type road bikes. Such bicycles were in Soviet times Ukraine, Shkolnik, Orlyonok and the like. They do not provide for gear shifting through sprockets. A similar type of brake is also used in bicycles with a planetary hub.
The principle of action is very similar to a drum brake. The roller brake itself on the bike is not inside the hub, but outside. It is attached to the bike frame and braking is not due to the foot brake, but due to the handle on the handlebars. From the brake lever there is a cable that, when pulled, triggers the roller brake mechanism.
The main parts of the bicycle brake are shown in the picture. Outside the drum wall, inside the drum there are 3 pads, 6 rollers and an eccentric. The eccentric is connected to the brake lever by means of a brake cable. When tensioned, the eccentric turns and begins to press the rollers to the pads. The pads, in turn, are pressed against the drum and braking occurs. They, like other brakes, have both pros and cons. At the same time, the advantages are quite significant.
In general, there are pluses and minuses as elsewhere. A roller bike brake is more suitable for non-aggressive driving in city, parks and the like. In the conditions of country roads, forests and the like, disc brakes are more suitable.
- Read all the information about the roller bike brake in this article.
- Read also what is better rim brakes or disc
Rim brakes are brakes in which braking occurs when the pads press on both sides of the rim of the bicycle, as a result of which there is a gradual braking until a complete stop. The brake lever is located on the handlebars of the bicycle and the braking force is transmitted either through the brake cable in the case of mechanical brakes, or through the hydraulic line if you have hydraulics installed on your bicycle. These bike brakes are currently considered the most common on beginner to intermediate mountain bikes.
By the type of attachment, they are divided into:
V-brakes are more commonly used on mountain bikes and other bikes where wide tires are present. In the case of narrow tires like racing bikes, caliper brakes are often used.
This is an outdated type of bicycle brake as it shows poor performance in extreme situations. Now they are mounted on some cyclocross bicycles, less often on road bikes. They are structurally simple. two elements are movably fixed in the holes. The drive is provided by the presence of the upper link.
These brakes are initially puzzling. “do they really work.” Budget models, when they have not yet got used to the pads, do not provide braking at all, this moment requires getting used to and specific skills. Later, when the pads are worn down, the brakes function well.
Mid-range models slow down well with normal pads. But high-quality options for brakes of this type work effectively with new pads, and after grinding them in, they brake well at all, comparable to other rim models and even with a budget version of disc mechanics. Effective cantilever brakes from Avid Shorty Ultimate or TRP Revo X brands.
These types of brakes are also outdated mechanics that are ineffective in extreme riding, although they are used on almost any road bike. The name indicates how the device works. The functioning is due to the clamping, like in a pincer, of the rim after acting on the mechanism by means of lateral pull. The brake is fastened with one bolt.