A bicycle brake reduces bicycle speed or prevents it from moving. The three main types are: brake rim, disc brakes, and drum brakes. There are different types of brakes used throughout history, and some are still in use today.
Most bicycle brake systems consist of three main components: a mechanism for riders to use brakes, such as brake levers or pedals; mechanisms for transmitting such signals, such as Bowden cables, hydraulic hoses, trunks, or bicycle chains; and the brake mechanism itself, the caliper or drum, to squeeze two or more surfaces together to transform, through friction, the kinetic energy of the bicycle and the rider into heat energy to be scattered.
Video Bicycle brake
History
Karl Drais included a rotating brake shoe that could be pressed against his 1817 Laufmaschine iron tire. It continued on the earliest bike with pedals, such as bones, which were fitted with a spoon brake to push onto the rear wheels. The brakes are operated by a lever or with a cable connecting to the handlebars. The rider can also slow down by holding the wheel pedal fixed.
The development of the next bike, sen-senja, both brake with a brake spoon or with paddle back. During its development from 1870 to 1878, there were various designs for the brakes, mostly operating in the rear wheels. However, as the rear wheels become smaller and smaller, with more heavy riders on the front wheels, the rear wheel braking becomes less effective. The front brake, introduced by John Kean in 1873, was generally adopted in 1880 due to greater stopping power.
Some penny-farthing riders only use paddle back and down and walk down steep hills, but most also use brakes. Having a brake means that riders can descend the hill by taking their feet off the pedals and putting their feet on the handlebars, though most riders prefer to go down and walk down steep hills. Placing the leg under the handlebars with the foot of the pedal placed on the footrest in the fork has resulted in a serious accident caused by the foot being caught in the fingers.
The alternative to the spoon brake for penny-farthings is the patented brake calipers by Browett and Harrison in 1887. Early versions of the caliper braking use rubber blocks to contact the outside of the penny-farthing small rear tires.
The 1870s and 1880s saw the development of safety bikes that roughly resembled bicycles today, with two wheels of the same size, initially with solid rubber tires. These are usually equipped with front spoon brakes and no rear brake mechanisms, but like penny-farthings they use fixed gears, allowing rear wheel braking by blocking the pedal movement. The relative fragility of the wooden rims used on most bicycles still prevents the use of the rim brakes. In the late 1890s came the introduction of brake rim and freewheel.
With the introduction of mass-produced pneumatic tires by Dunlop Tire Company, the use of brake spoons began to decline, as it tends to be quickly used through new thin tire tires. This problem causes demands for alternative braking systems. On November 23, 1897, Abram W. Duck of Duck's Cyclery in Oakland, California was granted a patent for Duck Roller Brake (US Pat. 594,234). Duck brakes use a rod operated by a lever on the handlebar to pull the twin rubber roller onto the front tire, braking the front wheels.
In 1898, after the advent of the freewheel shipping mechanism, the first internal brake coaster was introduced to the rear wheels. The coaster brakes are contained in the rear wheel hub, and are engaged and controlled by backpedaling, thus eliminating tire wear problems. In the United States, the brake coaster is the most common brake throughout the first half of the 20th century, often consisting of the only braking system on a bicycle.
Maps Bicycle brake
Brake type
Brake spoon
The brake spoon , or plunger brake is probably the first type of bicycle brake and precedes pneumatic tires. The brake spoon was used on penny points with solid rubber tires in the 1800s and continued to be used after the introduction of pneumatic-tyred safety bikes. The spoon brake is made up of a pad (often leather) or metal shoe (possibly rubber faced), which is pressed onto the top of the front tire. This is almost always operated by the right lever. In developing countries, the form of foot-driven disc brakes is sometimes attached to the old brake roadster. It consists of a spring flap attached to the rear of the crown of a fork. It is pressed against the front tires by the rider's feet.
Perhaps more than any other bicycle brake, the spoon brake is sensitive to road conditions and dramatically improves tire wear.
Although made obsolete by the introduction of duck brakes, brake coasters, and brake rods, the spoon brake continued to be used in the West with the addition of an adult bike until the 1930s, and children's bikes until the 1950s. In developing countries, they are produced until recently.
Duck brake
Created in 1897, the duck brake or duck roller brake uses a rod operated by a lever on the handlebar to pull twin friction rolls (usually made of wood or rubber) against the front tires. Installed on the axles secured with a friction washer and arranged at an angle to fit the shape of the tire, the rollers are forced against their frictionless friction when contacting the tire, thereby braking the front wheel. Tension spring to withstand roller from tire except during braking. Braking power is enhanced by an extra long brake lever mounted in parallel with and behind the handlebar, which provides additional leverage during braking (two hands can be used to pull the lever if required). Used in combination with the rear coaster brakes, day bikers can stop faster and with better braking modulation than may just use a spoon brake or rear brake coaster. Known as colloquial as duck brakes, this design was used by many famous riders that day, and is widely exported to the UK, Australia and other countries. In 1902, Louis H. Bill was granted a patent for a better version of the Duck Roller Brake (Patent 708114) for use on a motorcycle (motorcycle).
Brake rim
Rim brakes are so called because the braking force is applied by swiping pads to the rotating wheel edges, thus slowing it down and bikes. Brake pads can be made of leather, rubber or cork and are often installed in metal "shoes". The rim brakes are usually driven by levers mounted on the handlebar.
Advantages and disadvantages
Rim brakes are inexpensive, lightweight, simple mechanically, easily cared for, and robust. However, they perform relatively poorly when the rim is wet, and will brake unevenly if the rim is even slightly curved. Because rims can carry debris from the ground to the brake pads, the rim brakes are more susceptible to clogs with mud or snow than disc brakes (where the braking surface is higher than the ground), especially when driving on unpaved surfaces. The low price and the easy maintenance of the rim brakes make it popular on low-cost, low-cost commuter bikes, where the losses are reduced by non-challenging conditions. The light weight of the brakes also makes it desirable on street racing bikes.
Brake rims require regular maintenance. Brake pads wear out and should be replaced. And before they are completely discharged, their positions may need to be adjusted as they wear. Because most brake moves are not perfectly horizontal, the pads can lose their concentration as they wear, causing the pads to be uneven. Longer time and usage, rims become worn out. Rims should be checked for regular use as they may fail simultaneously if the braking surface becomes too obsolete. Wear accelerated by wet and muddy conditions. Brake rim requires a straight rim (not out-of-round or curved). If the rim has a pronounced shake, then the braking force may be intermittent or uneven, and the pads can rub the rim even when the brake is not applied.
During braking, the friction surface (brake pads and rims) will experience thermal heating. In normal use this is not a problem, since the brakes are applied with limited force and for a short time, so the heat quickly disappears into the surrounding air. However, on bicycles that are heavily loaded with long turcent, heat energy can be added faster than it can remove heat accumulate, which can damage the component and cause brake failure.
A ceramic coating for the rim is available which can reduce wear and also can improve wet and dry braking. It can also slightly reduce heat transfer to the inside of the rim as this is a thermal insulator.
Brake pads
Brake pads are available in various shapes and materials. Many consist of replaceable rubber pads that are held on mounting, or brake shoes, with post or bolt on the back for mounting on the brakes. Some are made as one part with attachments directly printed on the pad for lower production costs; Brake pads of this type of cartridge are held in place by metal split pins or threaded screw threads and can be replaced without moving the brake shoe from alignment to the rim. Rubber can be softer for more braking strength with less effort lever, or harder to live longer. Many pad designs have a rectangular shape; the other is longer and curved to fit the radius of the circle. Bigger bearings do not always provide more braking force, but will be used slower (in relation to thickness), so it can usually be thinner. In general, the brakes can be equipped with various bearings, provided the installation is compatible. Carbon fiber rims may be more sensitive to damage by unsuitable brake pads, and generally have to use non-abrasive cork pads.
Ceramic coated linings should be used with special bearings due to heat buildup at the pad-rim interface; Standard bearing can leave "glaze" on the ceramic braking surface, reducing the inherent roughness and causing heavy degradation in wet weather braking performance.
Characteristics of self-assisting
If the front brake is mounted behind the fork, so-called self-help effects occur. The frictional force between the brake shoe and the rim creates a bending moment that presses the shoe firmly on the rim so that it leads to a reinforced brake force. Self-assist reduces the input power required to apply the brakes. The disadvantage may be the fade brake - a non-linear relationship between actuation power and brake strength.
Type of brake rim
The following are among the many sub-types of brake rim:
Brake-actuation
"Rod-actuated brake", or simply "rod brake", (a brake lever roller in Raleigh terminology) uses a series of rods and pivots, rather than Bowden cables, to transmit applied forces to the hand lever to pull upward friction bearings against the inner surface , which faces the hub, from the wheel rims. They are often called "stirrup brakes" because of their shape. The rod brake is used with a rim profile known as the Westwood edge, which has a slightly sunken area on the braking surface and does not have the flat outer surface required by the brake applying the pads on the opposite side of the rim.
The back linkage mechanism is complicated by the need to allow rotation where the fork and handlebars are attached to the frame. The general setting is to comb the front rod brake with rear brake coaster. Although heavy and complex, the linkage is reliable and durable and can be repaired or adjusted with simple hand tools. The design is still in use, usually on African and Asian roadster like Sohrab and Flying Pigeon.
Caliper brakes
The caliper brake is a brake grade driven by a cable where the brakes are mounted to a point on wheels, theoretically allowing the arm to be automatically centered on the edge. The arm extends around the tire and ends with brake shoe pressing the edges. While some designs combine multiple pivot points - arm pivots on sub-frames - the entire assembly is still fitted to a single point.
The caliper brakes tend to be less effective because the tires become wider, and deeper, reducing the mechanical advantages of the brakes. So brake calipers are rarely found on modern mountain bikes. But they are almost everywhere on road bikes, especially the double-pivot side brake caliper.
Rem caliper side-drag
"Single-pivot side-pull caliper brakes" consist of two arcing arms that pass through the pivot on wheels and hold the brake pads on the opposite side of the rim. These arms have extensions on one side, one attached to the cable, the other to the cable house. When the brake lever is pressed, the arms move together and the brake pads push the rim.
These brakes are simple and effective for relatively narrow tires but have significant flexibility and result in poor performance if the arms are made long enough to fit the wide tires. If not well adapted, low-quality varieties tend to rotate to one side during actuation and tend to stay there, making it difficult to evenly distend brake shoes from the rim. These brakes are now used on cheap bicycles; before the introduction of dual-axle brake calipers they were used on all types of road bikes.
"Dual-pivot side-pull caliper brakes" are used on most modern racing bikes. One arm rotates in the middle, like a side pull; and other pivot on the side, such as the center pull. The cable house is attached as in the side-pull brake.
The side-pull side braking is enhanced by the mass market adoption of the double-axle side pull (an old design invented by Shimano in the early 1990s). These brakes offer higher mechanical advantages, and result in better braking. Double-pivot brakes are slightly heavier than conventional pull-side calipers and can not accurately track improper rims, or wheels that flex from side to side in the frame during hard climbing. It is common to see professional mountain climbing racers with rapid discharge on the rear brake, to remove obstacles from this source.
Rem caliper center drag
This type of brake has a symmetrical arm and therefore the center is more effective. The housing cable attached to the stop of the cable remains attached to the frame, and the inner wire bolts to the sliding parts (called "delta braking", "braking triangle", or "yoke") or small pulleys, which run on straddle cable connecting both brake sleeves. The tension on the wires is evenly distributed to both arms, preventing the brakes taking "sets" to one side or the other.
These brakes are reasonably priced, and in the past filled the price niche between the side-side brake models which are cheaper and more expensive.
U-brakes
"U-brakes" (also known as the "990-style" trademarked name) is essentially the same design as the center-tensile caliper brakes. The difference is that the two pivot arms are attached directly to the frame or the temporary fork that of the center-pull caliper brake attaches to the integral bridge frame that is attached to the frame or fork by a single bolt. Like roller cam brakes, this is a caliper design with a pivot located on top of the ream. So U-brakes are often interchangeable with, and have the same maintenance issues as, brake roller cam.
U-brakes were used on mountain bikes until the early 1990s, especially under the chainstays, the location of rear brake mounting which was then popular. These locations typically benefit from higher frame stiffness, an important consideration with strong brakes due to flex in stay will enhance the lever's ride and reduce the effective braking force. Unfortunately it is also very vulnerable to clogged by mud, which means that U-brakes are quickly disliked by cross country bicycles.
U-brakes are the latest standard on freestyle BMX frames and forks. The main advantage of U-brake over cantilever and linear-pull brakes in this application is that the brake aside and cabling system are minimal, and the open part is smooth. This is especially useful for freestyle BMX bikes where prominent parts are susceptible to damage and may interfere with the body or clothing of the rider.
Cantilever brakes
The cantilever brake is a brake class in which each arm is attached to a separate pivot point on one side of the seat or fork. So all cantilever brakes are dual-pivot. Both the first and second class lever designs exist; the second class is the most common. In the design of a second class lever, pivot the arm under the rim. Brake shoes are mounted on top of the pivot and pressed towards the rim as both arms are drawn together. In a first-class lever design, the pivot sleeve is on the rim. Brake shoes are installed under the pivot and pressed towards the rim as both arms are forced apart.
Due to the wider possible distance between mounts and bearings, cantilever brakes are often preferred for bikes that use wide tires, such as on mountain bikes. Since the arm only moves in a designed bow, the brake shoes should be adjustable across multiple planes. So cantilever brake shoe is very difficult to adjust. When brake shoes from second-class cantilever brakes are worn, they rise lower to the rim. Finally, one can go under the rim, so the brake is not working.
There are several types of brakes based on brake cantilever design: cantilever brakes and direct-pull brakes - both second-class lever designs - and cam roller brakes and U-brakes - are both major class lever designs.
Traditional cantilever brake
This type of brakes before the date of the direct-pull brake. It is a center-pull cantilever design with the arm tilted outward protruding on each side, stopping cables on the frame or fork to end the cable housing, and the straddle cord between the arms similar to the center-pull caliper brakes. The cable from the brake lever pulls up on the straddle cord, causing the brake arm to spin upward and inwards thus pressing the rim between the brake pads.
Traditional cantilever brakes are difficult to adapt to the bike suspension and are somewhat protruding from the frame. Thus, they are usually only found on bicycles without suspension.
V-rem
"Linear-pull brake" or "direct-pull brake", commonly called "br" V "brand Shimano, is a side pull version of the cantilever brake and mounted on the same frame boss. However, the arms are longer, with housing cables attached to one arm and the other. When the cable pulls into the house, the arms are drawn together. Because the housing enters vertically above one arm but the force must be transmitted laterally between the arms, the flexible housing is extended by a rigid tube with a 90 ° bend known as "noodles" (noodles with 135 Â ° indentations used where the front brake is operated by hand right, as this gives a smoother curve in the cable house). Noodle chair in stirrups stuck to the arm. Flexible baskets often cover open wires.
Since there is no intervening mechanism between cable and arm, this design is called "direct tug". And since the arm moves at the same distance as the moving wires associated with its housing, its design is also called "linear pull". The term "V-brake" is a trademark by Shimano and represents the most popular implementation of this design. Some high-end v-brakes use a four-axle parallel movement so that the brake pads touch at nearly the same position in the hub regardless of wear and tear.
V-rem works well with suspension systems found on many mountain bikes as they do not require a separate cable stop on the frame or fork. Due to the higher mechanical advantages of V-brake, they require a brake lever with longer cable trips than levers intended for older brake types. The mechanical disc brakes (ie the activated cables) use the same number of travel cables as the V-br, except those described as "paths" specific. As a general rule, mechanical disc brakes for so-called "flat bar" bikes (especially mounts and hybrid bikes) are compatible with V-brake levers, while mechanical disc brakes are meant for "drop-bar" bikes that are compatible with brake cable brake design the older (cantilever, caliper, and U-brake).
Poorly designed V-brakes can experience a sudden failure when the noodle tip pulls through the metal stirrer, leaving the wheels powerlessly braking. Although noodles can be regarded as a service item and changed regularly, the holes in the stirrups can dilate through wear and tear. Sanggurdi usually can not be replaced, so good quality brakes use metal that is durable for stirrups.
"Mini V-brakes" (or "mini V's") are V-brakes with shorter arms, usually between 8 and 9 cm. This reduces the pull of the necessary cables, making them compatible with the brake levers intended for cantilever brakes. Mini V-brakes retain a special advantage for the V-brakes as it does not require extra cable cessation. On the downside, their shorter arms provide very small tires and wheels and generally make the settings less forgiving: they can only accommodate smaller tire sizes compared to cantilever brakes, can cause problems for fender mounting, can be more easily clogged by mud, and they can make it more difficult to replace the wheel.
Roller cam brakes
"Roller cam brakes" is a center-pull cantilever brake that is driven by a cable that pulls a two-sided cam cam. (First and second class lever designs exist: first class is most common and is described here.) Each arm has a cam follower. As the cam presses the follower, it forces the arm to come loose. When the top of each arm moves outward, the brake shoe under the pivot is forced inside against the rim. There are many that support the roller cam brake design. Since the cam controls the closing rate, the clamping force can be made non-linear with traction. And since the design can provide a positive mechanical advantage, maximum clamping force can be higher than other types of brakes. They are known to be strong and in control. On the downside, they need the skill to organize and can complicate the wheel changes. And they need care: like U-brakes, when pads wear them higher; unless it is re-adjusted, can eventually contact the tyre sidewall.
The roller cam design was first developed by Charlie Cunningham of WTB around 1982 and licensed to Suntour. The brake roller cam was used on an early mountain bike in the 1980s and into the 1990s, fitted to a head tube and a fixed seat at a standard location, and under a fixed chain to increase the stiffness as they were not prominent to disrupt the crank. It is not unusual for a bike to have one single brake roll (or rem-U) combined with another type. They are still used on BMX bikes and on their backs.
There are two rare variants that use the principle of roll cam. For locations where the center tension is not appropriate, the "side wheel pull" side pull pull "is developed." Also a first-class cantilever, it uses one side of the sliding cam (toggle) against one arm attached by a link to the other arm.When the cam presses the follower, this is also transmitted to other sleeves through a link, and specifically for a suspension fork where the housing should end up on the brake frame, a side-pull "side-pull" handbrake is developed.In the design of the saber ridge, the end of the cable is fixed and the housing moves one-sided cam.
Delta Brakes
"Rem delta" is a road bike brake because of its triangular shape. The cable enters in the middle, pulling the angle from the parallelogram connections placed inside the brake on two opposite corners, pushing out at the other two corners to the brake arm above the pivot, so the arm under the pivot pushes the cushion against the rim. The feature of the design is that the mechanical advantages vary as a tangent function throughout its range, where most of the other designs are fixed.
Many consider the brakes attractive, and have lower wind profiles than some other common brakes. However, Quarterly Bicycles criticize the delta brakes because of its weight, provide mediocre stopping, and suffer adverse mechanical advantages of variables. In particular, with small parallelograms, the use of pads causes mechanical gain to increase dramatically. However, with high leverage, the levers are insufficient to fully apply the brakes, so the rider can have a brake that feels normal in light braking but can not be applied harder for hard braking.
The base design date is at least 1930s. They were made most prominent by Campagnolo in 1985, but the brakes based on the same mechanism were also made by Modolo (Kronos), Weinmann, and others. They are no longer made and are now uncommon.
Brake hydraulic rim
This is one of the most common types of brakes. They are mounted both on the same pivot point used for cantilever and linear-pull brakes or they can be mounted on four bolt brakes found in many experimental frames. They were available on some high-end mountain bikes in the early 1990s, but decreased in popularity with the advent of disc brakes. The benefits of moderate performance (greater strength and control) they offer on wheel-driven brake wheels are offset by greater weight and complexity.
Disc brakes
A disc brake consists of a metal disc, or "rotor", attached to a rotating wheel hub with wheels. The calipers are attached to the frame or fork along with the pads pressing the rotor for braking. As the bearing drags against the rotor, the wheel - and thus the bike - is slowed as kinetic energy (motion) is converted into heat energy. Disc brakes can be mechanically moved by cable, or hydraulically.
The most common disc brakes for mountain bikes (including almost all downhill bikes), and also seen on some hybrid bikes and touring bikes. Disc brakes are sometimes used as drag brakes.
Many hydraulic brake discs have an adjustment mechanism so that when the brakes are off, the pistons keep the distance from pad to disk consistent to maintain the same brake lever jump. Some hydraulic brakes, especially older ones, and most mechanical discs have manual controls to adjust the pad-to-rotor slot. Some adjustments are often needed during the lifetime of the pads.
Advantages
Disc brakes tend to work well in all conditions including water, mud and snow due to several factors:
- Braking surfaces away from the ground and possible contaminants such as mud that can coat or freeze on rims and pads. With rim brakes, the first point that builds mud on mountain bikes ridden in thick mud is usually the brakes. Mountain bikes with disc brakes are less susceptible to the buildup of mud if the back frame and front fork have sufficient permission from the wheels.
- Disc brakes may be made of materials that dissipate heat better than wheel rims, but small-sized sports discs will be too small to take advantage of facts
- There is a hole in the rotor, providing a water path and debris to get out from under the pads.
- Wheel rims tend to be made of light metal. Brake discs and pads are harder and can accept higher maximum loads.
- It is possible to ride a bicycle with a curved wheel if it has a disc brake, which is impossible with a rehearsal rake because the bent wheel will bind on the brake pads.
Other reasons include:
- While all types of brakes will eventually fade braking surfaces, brake discs are easier and less expensive to replace than wheel or drum rims.
- Extremely wide use of tires supports disc brakes, since rim brakes require longer arms to clean wider tires. Longer arms tend to be more flexible, decrease braking. Disc brakes are not affected by the width of the tire.
- Unlike some of the more rare rim brake designs, disc brakes are compatible with front and rear suspensions.
Losses
- Disc brakes require hubs built to receive discs, and forks (for front brakes) or frames (for rear brakes) made for receiving calipers. Front hubs designed for discs often move the left flank hub inward to make room for the disc, which causes the wheel to be dished. The dished wheels are laterally weaker when forced to the non-disc side. Other hubs use conventional flange spans and provide unplaced wheels, but require less commonly wide forks.
- The rim brakes work directly on the edges and the tires are mounted; Disc brakes apply a potentially large torque moment moment in the hub. The latter has two major weaknesses:
- torque moments should be transmitted to the tire through wheel components: flanges, fingers, nipples, and reams talking in bed. Engineered disc brakes reduce weight by not having most of the metal rim components
- The front disc brakes place the bending moment at the fork between the caliper anchor point and the end of the pause. To overcome this moment and to support anchor point and caliper weight, the fork must have a certain size (most likely heavier).
- Heavy fork and wheels add to heavy losses in the brake assembly itself.
- Heat buildup can cause failure with disc brakes. Disc brake discs in the same way as the rim brakes the heat rim, but the discs provide a smaller surface inherently to remove heat. Excessive heat causes the hydraulic fluid to boil, resulting in faded brakes or total failure. Overheating is more common in road cycles assuming the brakes are too small to reduce weight. The case of recorded disk brake failure typically involves several kilometers downhill, combined with a small disk of weight.
- The design and position of the brake discs can disrupt the pannier racks that are not designed for them. For this reason, many manufacturers produce "disk" and "non-disk" versions.
- There are some problems using disc brakes with a particular frame design. Under hard braking, the front wheels can get out of the dropout. The problem has occurred when the brake pads and breaks are aligned so that the brake reaction force tends to pull the wheel out of the dropout. Under repetitive hard braking, the axle moves in pauses in a manner that releases rapid discharge. The rider must make sure the skewer is tightened properly before driving. Forks that use different brake/dropout orientations or via axis are not subject to this problem.
Hydraulic vs. "mechanical"
There are two main types of disc brakes: "mechanical" (wired-activated) and hydraulic. The advantages of cable-driven disc brakes are lower cost, lower maintenance, and lighter system weight. Hydraulic disc brakes, on the other hand, offer more braking power and greater control over braking power. Traditionally driven cables are the only type of brake disc that can be used with the brake lever found on the drop handlebars, but this is no longer the case.
Single vs. actuation. double
Many disc brakes have pads that are moved from both sides of the caliper, while some have only one pad in motion. Double actuation can move both pads relative to the caliper, or it can move one pad relative to the caliper, then move the caliper and other pad relative to the rotor, called "floating caliper" design. A single actuation brake uses a multi-part rotor that floats axially on the hub, or bends the rotor to the side as needed. Bending the rotor is theoretically lower, but in practice provides good service, even under high strength braking with heat discs, and can lead to more progressivity.
Multiple pistons
For disc brakes with hydraulic systems, high-performance calipers typically use two or three pistons per side; Cheap and low-performing calipers often only have one per side. Using more pistons allows a larger piston area and thereby increases leverage with a given master cylinder. Pistons can also have several sizes so that the pad styles can be controlled across the pad surface, especially when the pad is long and narrow. A long length pad may be desirable to increase the pad area and thereby reduce the change frequency of the pad. Conversely, one large piston may be heavier.
Standard of installing Caliper
There are many standards for the installation of disc brake calipers. AKU S. (International Standard) is different for 160mm and 203mm rotor and differs between fork with QR and 20 mm through shaft. The post-installation standard also differs based on the size of the disc and the type of axle. Many incompatible variants are produced over the years, mostly by fork manufacturers. The mounts used on Rockshox Boxxer are the most common of these special mounts, but most fork manufacturers now use IS or post-mount standards for their current forks. As a point of reference, Hayes currently sells no fewer than 13 different adapters to fit its brakes into various mounting patterns.
Advantages and disadvantages of different types of mounts
The post-installation loss is that the threaded bolt directly to the fork lowers. If the thread is removed or if the screw is jammed, the thread needs to be repaired, or the seized bolt is drilled out. The frame manufacturer has standardized the IS stand for rear disc brake holder. In recent years, the mountain pegs have gained ground and become more common. This is largely due to the decrease in manufacturing and part cost for brake calipers when using post-installation. The limitation of installation is that the rotor location is more limited: it is possible to confront a combination of unsuitable hub/fork, where the rotor is out of range.
Standard disk installs
There are many options for rotor installation. IS is a six-bolt mount and is an industry standard. Centerlock is patented by Shimano and uses a splined interface along with locking to secure the disk. The advantage of centerlock is that the splined interface is theoretically more rigid, and removes disks faster because it only requires one lock to be removed. Some of the disadvantages are that the design is patented and requires a license fee from Shimano. The Shimano cassette locking device (or an external BB tool in the case of a hub through axle) is required to remove the rotor and is more expensive and less common than the Torx key. The six-bolt IS gain is that there are more options when it comes to hubs and rotors.
Standard installation examples are shown here:
- Centerlock (owned by Shimano)
- International Standard (IS) (widely used) 44mm BCD
- 3-bolt Pattern of Technology Expectation (property rights)
- Pattern 4-bolts of Rohloff (proprietary)
Disk size
The rotor comes in a variety of sizes, such as 160 mm (6,299 inches) 185 mm (7,283 in) and 203 mm (7,992 in) diameters. Other sizes are available because manufacturers create special discs for their calipers - dimensions often vary several millimeters. The larger rotor provides a larger braking force for the given pad pressure, based on the longer arm of the moment for the calipers acting. The smaller rotor provides less power but also lighter and better protection from impact. Larger rotor dissipates heat faster and has a larger amount of mass to absorb heat, reduce brakes faded or fail. Decreased motors usually have larger brakes to handle larger braking loads. Cross country bikes typically use smaller rotor that handle smaller loads but offer considerable weight savings. It is also common to use larger diameter rotors on the front wheels and smaller rotor on the rear wheels because the front wheels do the most braking (up to 90% of the total).
Brake drum
The bicycle drum brake operates like a car, although variations of the bike use wires rather than hydraulic actuation. Two pads are pressed out against the braking surface inside the hub shell. The inner diameter of the shell on the bike drum brakes is usually 70-120 mm (2,756-4,724 deep). Drum brakes have been used on hubs and front hubs with internal and external freewheels. Drum wiring and drum operated drums have been widely produced.
The roller brake is a drum brake operated with modular cables made by Shimano for use on special front and rear hubs. Unlike traditional drum brakes, Rol Brakes can be easily removed from the hub. Some models contain a torque divider device called a power modulator designed to make the wheels difficult. In practice this can reduce its effectiveness on a bicycle with an adult-sized wheel.
The drum brakes are most common on utility bikes in some countries, especially the Netherlands, and are also often found on transport bikes and velomobiles. Older tandem bikes often use rear drum brakes as drag brakes.
The drum brakes provide consistent braking in wet or dirty conditions because the mechanism is completely enclosed. They are usually heavier, more complicated, and often weaker than rim brakes, but they require less maintenance. The drum brakes do not adapt well to release the fast axle fastener, and removing the drum brake wheel requires the operator to disconnect the brake wire and its axis. They also need a torque sleeve that must be attached to the frame or fork of the bike, and not all bikes are built to accommodate binding or tolerate the style of the application.
Rem coaster
First discovered in 1898 by Willard M. Farrow, "brake coaster", also known as "rear brake pedal" or "brake foot" ("torpedo" or "counter" in some countries, in Italy "contropedale"), is a kind of drum brake that is integrated into the rear hub with an internal freewheel. The freewheeling function is the same as other systems, but when it comes back pedaling, the brakes move after a fraction of a revolution. The coaster brakes can be found at both a single speed and internal directed hub.
When the hub is moved forward, the sprockets move the screw that forces the clutch to move along the shaft, pushing the hub shell or gear assembly. When pedaling upside down, the screw pushes the clutch in the opposite direction, forcing it between the two brake shoes and pressing them against the brake coat (which is the steel layer inside the hub shell), or into a separate collar and extending it against the mantle. Braking surfaces are often made of steel, brass and bronze elements or bronze phosphors, such as the Perry Coaster Hub made by Birmingham. Coarse coaster brakes also exist, usually on a children's bike, where a jagged steel brake cone grips the inside of the hub shell directly, without brake pads or a separate mantle. It offers less progressive action and is more likely to accidentally lock the rear wheels.
Unlike most drum brakes (but like a roller brake Shimano) the brake coaster is designed to run with all its interior coated lubricants for quiet operation and smooth engagement. Most gray molybdenum disulphide greases work well in the coaster brakes, with their metal-to-metal friction surfaces.
Coaster-brake bikes are generally equipped with single gears and chain wheels and often use a 1/8 in (3.2 mm) wide chain. However, there are several models of brake hub coasters with dÃÆ' Â © railleurs, such as Sachs 2x3. It uses a special extra-short railsure that can stand with often straightened strength and does not require an excessive amount of rotation of the upside pedal before the brake moves. The coaster brakes have also been incorporated into the wheel hub design - eg AWC and SRC3 from Sturmey-Archer, and Shimano Nexus 3-speed. They can have up to eight gears, like the Nexus inter-8.
The brake coaster has the advantage of being protected from the elements and thus performs well in rain or snow. Although the coaster brakes generally run for years without the need for maintenance, the brakes are heavier than the ream brakes to be repaired if necessary, especially the more sophisticated types with widespread brake shoes. The coaster brakes also do not have sufficient heat dissipation to use on the long demcent, a legendary characteristic made through an event like the 'Repack Downhill' race, where drivers will almost certainly need to pack the coaster brakes after the fat is melted or smoked because of the heat from the downhill road long. The coaster brakes can only be applied when the crank is flat, limiting how fast it can be applied. Because the coaster brakes are only made for the rear wheels, they have a common disadvantage in all the rear brakes to easily shift the wheels. This disadvantage, however, can be alleviated if the bike also has a hand-operated front brake lever and the cyclist uses it. Another disadvantage is that the brake coaster is completely dependent on a fully intact and active chain. If the chain breaks or is separated from the wheel chain and/or rear sprocket, the coaster brake does not provide any braking power. Like all brake hubs except brake discs, the brake coaster requires a reaction arm to be connected to the frame. This may require unbolting when the wheels are removed or driven at the tip of the fork to adjust the chain voltage.
Drag brakes
A brake drag is a type of brake determined by its use not by its mechanical design.
Drag brakes are meant to provide a constant deceleration force to slow the bike over a long hill rather than to stop it - a separate braking system is used to stop the bike. Drag brakes are often used on heavy bikes such as tandem in mountain areas where the use of extended rim brakes can cause the rim to be hot enough to explode. A typical drag brake has long been a drum brake. The biggest producer of this type of brake is Arai, whose brakes are connected to a hub with a conventional freewheel threading on the left side of the rear hub and operated through a Bowden cable. In 2011, drum brakes Arai has been out of production for several years, with stocks remaining close to depletion and units used for premium prices on internet auction sites.
Recently, large rotor disc brakes are used as drag brakes. DT-Swiss made adapter for mate disc rotor with threaded hub for drum brake Arai, but this still leaves problem fit caliper.
Rem Band
Rem band consists of bands, straps, or cables that wrap drums that spin with wheels and are pulled tight to produce braking friction. Brake band appeared as early as 1884 on a tricycle. Star Cycles introduced the band remakes in 1902 on bikes with freewheels. Rem bands are still produced for bikes today.
A rim wheel wheel , as applied to Yankee bikes by Royce Husted in the 1990s, consisted of stainless-steel wires, wrapped in kevlar gloves, which rose in a U-shaped channel next to the wheel rims. Squeeze the brake lever tightens the cable to the channel to produce braking friction. A spring re-slows the cable when the brake lever is removed, no adjustments are required, and the brakes get stronger when wet. Husted said his inspiration was a band brake used on industrial machines. Yankee bikes only include the rear brake, but it meets the standards of the US Consumer Product Safety Commission.
Actuation Mechanism
The activation mechanism is part of the brake system that transmits the style from the rider to the actual braking system part. The actuation mechanism of the brake system can be either mechanical or hydraulic.
Mechanical
The main modern mechanical actuation mechanism uses a brake lever incorporated with a Bowden cable to drive the brake sleeve, thus forcing the bearing against the braking surface. Cable mechanisms are usually cheaper, but may require some maintenance associated with the open area of ​​the cable. Other mechanical actuation mechanisms exist: see Coaster brakes for rear pedal propulsion mechanisms, and rod-driven brakes for mechanisms that incorporate metal rods. The first spoon brake is moved by a pulled cable by turning the end of the handlebars.
Hydraulics
The hydraulic brakes also use the brake lever to push the liquid through the hose to move the piston in the caliper, thus forcing the bearing against the braking surface. While hydraulic disc brakes exist, today the hydraulic actuation mechanisms are mostly identified with disc brakes. Two types of brake fluid are used today: mineral oil and DOT fluids. Mineral oil is generally inert, while DOT is corrosive to paint the frame but has a higher boiling point. Using the wrong liquid may cause the seal to swell or become rusty. The hydraulic mechanism is closed and therefore tends to have problems related to contamination in open areas. Hydraulic brakes seldom fail, but failure tends to be complete. The hydraulic system requires special equipment to be repaired.
Hydraulic brake fluid
Hydraulic disc brakes use two common forms of fluid: DOT 4 or DOT 5.1 hybrid grade which is hygroscopic and has a boiling point of 230 ° C; and mineral oil that is not hygroscopic and has various boiling points depending on the type. O-rings and seals inside the brakes are specifically designed to work with one or the other liquid. Using the wrong type of liquid will cause the seal to fail resulting in a "slippery" feeling on the lever, and the caliper piston is irreversible, so friction disks are common. The brake fluid reservoir is usually marked to indicate the type of brake fluid to be used.
Hybrid
Some older designs, such as AMP brakes and Mountain Cycles, use cables from the lever to the caliper, then use master cylinders that are integrated into the piston. Some Santana tandem bikes use cables from the lever to the master cylinder mounted near the head tube, with a hydraulic channel to the rear wheel calipers. Such "hybrid" designs allow the levers of hydraulic systems while allowing the use of cable brake levers, but may be heavier and may suffer grit intrusions in standard cables.
The older Sachs drum brake kit ("Hydro Pull") makes it possible to rebuild the regular Sachs bicycle drum brakes to the lever and hydraulic action. The piston is added outside the drum instead of a bowden clamp. This solution is often seen in the modification of the Long John cargo bike, allowing low friction lever to pull the front wheel brake action. After Sachs discontinues the production of this kit, the same solution is sometimes done by welding the Magura piston to the cylinder lever drum. Welding is necessary because Magura's actions are reversed with those in the Sachs kit.
Brake lever
Brake lever is usually mounted on handlebar easy to reach from the hands of riders. They may differ from or be integrated into the shifting mechanism. The brake lever transmits the force applied by the rider through a mechanical or hydraulic mechanism.
The bike with the handlebars can have more than one brake lever for each brake to facilitate the braking of some hand positions. The lever that allows the rider to work the brake from the top of the bars, introduced in the 70s, is called the extension lever, the safety lever or, because of their reputation as not being able to move the entire lever brake lever main, suicide levers . The brake lever mounted on top of the modern one, called the interrupt brake lever, uses a completely different actuation method and is considered more secure.
The mechanical advantage of the brake lever must be matched with the brakes connected so that the rider has enough leverage and travels to run the brakes. Using unsuitable brakes and levers can produce too many mechanical advantages and therefore not enough journey to actually run the brakes (v-brakes with conventional levers) or too little mechanical advantage, requires a very strong pull to brake hard (v-brake lever with other types of brakes).
Mechanical brake levers (cables) come in two varieties based on the length of retractable brake wires for a given range of lever movements:
- Drag standards levers work with most brake designs, including caliper brakes, traditional cantilever brakes, and mechanically driven brake drives for "Road".
- Long pull lever works with "direct-pull" disc brakes, such as Shimano "V-Brakes", and mechanically activated brake discs for "Mountain".
The adapter is available to allow the use of one type of lever with an incompatible rim brake type. Some brake levers have adjustable leverage that can be made to work with both types of brakes. Others vary their mechanical advantage when the moving lever to move the pad quickly at first, then give more lever after touching the brake surface. The hydraulic brake lever moves the piston into a liquid reservoir. The mechanical advantage of the lever depends on the design of the brake system.
Braking Technique
The dynamics of the bike movement will cause weight transfer to the front wheels during braking, increasing traction on the front wheels. If too much power is applied to the front brake, momentum can cause riders and bicycles to pass - the type of accident sometimes called "endo". The rear wheel tower can serve as a signal to reduce the force on the front brake.
On tandem bikes and other long wheel bikes (including recumbent and other specialty bikes), the lower relative mass centers make it almost impossible for heavy front braking to flip the bike; the front wheels will slide first.
In some situations, it is advisable to slow down and use more rear brakes and less front brakes:
- When not familiar with bicycle braking characteristics. It is important to test the brakes and learn how much hand strength is needed when first driving it.
- When leaning on the turn (or better, brake before spinning).
- Slippery surface, such as wet pavement, mud, snow, ice, or loose rock/gravel. It is difficult to recover from the front wheel skid on slippery surfaces, especially when leaning.
- Wavy Surface: If the front wheel is released from the ground during braking, it will stop completely. Landing on the front wheels that stop with the still applied brakes will most likely cause the front wheel to slip and can flip the rider over the handlebars.
- Very loose surfaces (such as loose gravel and loose dirt): In some loose surface situations, it may be useful to lock the rear wheels completely to slow or maintain control. On a very steep slope with loose surfaces where any braking will cause the wheels to slip, it would be better to maintain control of the bike with more than one rear brake normally. But the wheels do not stop spinning completely, because this will produce very little control.
- Steep Descents: the tilt angle makes the front flip easier to achieve, and moreover the front wheel skid will be very difficult to recover (very likely), while the rear skid still pulls the bike without losing too much control. Long liquids of descents: alternating front and rear brakes can help prevent hand fatigue and overheating of wheel rims that can cause catastrophic tire bursts, or boil from hydraulic fluid in case of hydraulic disc brakes.
- A flat front tire: braking a tire that has little air can cause the tire to slip from its lips, which is likely to cause an accident.
It is common to place the front brake lever on the left in countries driving on the right side, and vice versa, since the hands on the side closer to the middle of the road are more commonly used for hand signals, and the rear brakes can not throw cyclists forward.
Bicycle without brake
Track bikes built without brakes so as to avoid sudden changes in speed while racing in velodrome. Because the bike track has a fixed tooth, braking can be done by flipping the force on the pedal to slow down, or by locking the pedal back and pushing the slip. Fixed gear road bikes may also have no brakes, and slow or stop them like on a bike track. Many fixed gear bikes feature front brakes for safety reasons, or because it is a legal requirement. Some BMX bikes do not have brakes. The usual method to stop is for the rider to put one or both feet on the ground, or to wedge the leg between the seat and the rear tire, effectively acting as a spoon brake. Cycle Speedway is a kind of track near racing in England, Poland, Australia, and France. Special bikes made have one freewheel and no brakes. Slowdown is done when cornering by dragging the inner legs. This bike is not meant to be used on the road and kept on track.
In Belgium, Australia, Germany, England, France, Poland, Japan, Denmark and Finland, it is illegal to ride a bicycle without brakes on public roads.
See also
- The dynamics of bicycles and motorcycles
- Detangler
- Glossary of cycling
- List of bicycle components
References
Source
Source of the article : Wikipedia
0 Comments