Checking the readiness of the system for adjustment
- The adapter to which the caliper is attached is well secured to the frame or fork (bolts are tight).
- The already tested rotor is securely fixed with screws on the hub.
- The wheel is mounted on the bike, the eccentric / nuts are tightened.
- The lamb for adjusting the cable tension is unscrewed no more than 1.5 turns (located next to the handle or caliper).
- The cable is fixed on the movable arm of the machine.
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.
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.
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.
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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.
How to pull
Proceed in the reverse order of loosening the cable and you will get the desired result.
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.
How to set up rim brakes on a bike
The braking system is one of the most important technical components of a bicycle. The safety of both the cyclist and other road users directly depends on its condition. Good brakes are essential in any situation, from riding in parks to tough cycling.
In the modern classical sense, a bicycle brake is a pressure mechanism that acts on the wheel rim. In fact, there are several types of brakes, however v-brake (rim) is the most common option on bicycles of various classes.
Varieties of rim brakes
Rim brakes are divided into several types:
- 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.
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.
How To Convert To Disc Brakes From V-Brakes On Mountain Bike
Device and principle of operation
The difference between the principles of operation of disc and mechanical brakes is insignificant. But, there are still differences in their device. Let’s consider step by step, starting with the mechanical type, which is arranged as follows:
- Brake handle. It is fixed on the steering wheel, for the convenience of squeezing, with a clamp. It is designed to transfer force to the brake pads, bringing them into action.
- Cable adjuster with lock nut. The first element serves as a regulating device for limiting the cable tension. The second is for fixing the regulator itself.
- Brake lever adjuster designed to determine a comfortable distance to the handlebars.
- Cable jacket. protecting it from dirt, mechanical damage.
- To fix the cable, a clamp in the form of a bolt is used, with the possibility of adjustment
- The mechanism that allows the cable to be set in motion, when pressed on it, is called a caliper. Its action is not possible without brake pads. rubber or metal fragments that ensure a tight clamping of the disc.
- Directly disc (rotor). It locks onto the wheel hub.
Figures 1 and 2 show schematically all of the above details.
Figure: Bicycle brakes
Figure: appearance of the brake lever with main elements
How to set up disc brakes on a bicycle
Running a bike is one thing, but fixing it is another. Even skilled and experienced cyclists are faced with the problem of incorrect / defective disc brakes. You can deal with this phenomenon if you clearly know the principle of operation and the structure of the system. And you should start with these main points.
It is possible to fix problems on a bicycle, even on your own, without proper experience and training. All you need to do is follow the instructions above. You should not rush through the setup, as this is a delicate process, and everything will work out for you!
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 located 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.
The main differences between hydraulic and mechanical disc brakes
The main difference between the hydraulic and mechanical types is the principle of transferring the force exerted on the handle to activate them. So, if a cable serves as a conductor of the pressure force in mechanics, then in hydraulics it is a liquid. Both brake and mineral oil (depending on the manufacturer) can be used as a fluid. Both of them are good in their own way, and their effect differs from each other to an insignificant degree. The photo shows a schematic representation of the device of the hydraulic type of disc brakes.
Photo: the main elements of the hydraulic system of disc brakes
Progress Can’t Be Stopped. Road Bike Disc Brakes
Models of road racers with discs appeared on sale several years ago, then I wrote a note Do road racers need disc brakes, but they could not be used in professional competitions.
Last Tuesday, the UCI officially gave the green light to the use of disc brakes in road cycling, although not completely. so far they decided to experiment with cyclists.
This year it will be possible to test wheels in a real race only in August and September, the UCI allowed each team to choose two events during these months. Testing will also be selectively tested in 2016.
Based on this experience, the UCI will come to a final decision: if everything goes smoothly, all bikes will be equipped with disc brakes in the 2017 racing season.
Everyone who has seen at least one stage of cycling races has a legitimate question. will the athletes be crippled by the sharp edges of the rotors in the event of a massive blockage? Apparently, the test period is intended, among other things, for the accumulation of statistics on such incidents.
Marketing departments of bike manufacturers are eagerly rubbing their paws. as soon as the pros start to ride on disks, then all bike fetishists will throw away their instantly obsolete top junk and order new models, one and a half times more expensive.
I had no doubt that disc brakes would come to professional cycling, progress, as they say, cannot be stopped. Even if this progress is not particularly needed. The cycling industry needs to move, and without systemic changes it is difficult to justify the need for expensive upgrades.
Presumably, the next change will be the official UCI road bike weight limit. the road bike must be no lighter than 6.8 kg. This is to prevent manufacturers from getting carried away and sacrificing component reliability to keep weight down.
But in our time, the technology of relief is so advanced that it is necessary to lower the limit? I think that such high-level discussions are not far off.
Well, as for disc brakes on highways, we need to prepare for the fact that within a few years they will rapidly fall in price and penetrate into the segments of the middle and entry price level, as was the case with discs on MTB.
Hence the question for readers who ride road bikes (or dream of doing it), what do you think about wheels? Do you like the idea of having hydraulic brakes on the road?
On my own I will say that I have already resigned myself to progress, and now I want a carbon fiber road with disc brakes and an electronic transmission. But the toad resists desperately!
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