| Early bicycles such as the high wheeled | | | | including water and mud. They also avoid the |
| penny-farthing bikes had no brakes as we would | | | | problem that rim brakes have of wearing out the |
| recognize them today. As the machines were | | | | wheel rims, especially in muddy conditions, as well |
| fixed gear bicycles a rider could reduce speed by | | | | as the requirement that the rim be true. Also, disc |
| reversing the thrust on the pedals. Otherwise, a | | | | brakes offer better modulation of braking power |
| rider who wanted to stop quickly had to jump off | | | | and generally require less finger effort to achieve |
| the bike as it was moving. Unsurprisingly there | | | | the same braking power. The disadvantages are |
| were many accidents, some of them fatal, which | | | | that they are usually heavier and more expensive |
| limited the appeal of cycling mostly to young and | | | | than rim brakes, and require a hub built to accept |
| adventurous men. | | | | the disc and a bicycle frame or fork built to |
| The 1870s saw the development of the "safety | | | | accept the caliper. Also, rigid forks on road bikes |
| bicycle" which was roughly the bicycle we would | | | | and tandems that are made to handle the forces |
| recognize today, with two wheels of equal size, | | | | of a front disc brake are heavier and may not |
| initially with solid rubber tires. These were | | | | have the ride quality of a regular fork. |
| generally equipped with a front spoon brake and | | | | Furthermore, a disc brake puts more stress on a |
| no rear brake, although with no free wheel, | | | | wheel's spokes than a rim brake, since the torque |
| back-pedalling was an option. This was | | | | of braking occurs between the hub and the rim |
| undoubtedly a big improvement on having no | | | | with disc brakes, unlike with rim brakes. For this |
| brakes at all, but it was not very powerful and | | | | reason, cross-lacing of spokes is usually employed |
| almost useless in wet weather. | | | | with disc brakes, while rim brakes sometimes |
| With the introduction of the pneumatic tire also | | | | allow the option of lighter radial lacing. |
| came the next advance in bicycle braking around | | | | There are two general categories of disc brakes, |
| the 1890s, the invention of the rim brake. This is | | | | mechanical and hydraulic. Mechanical disc brakes |
| the type of brake most commonly used on | | | | (which are almost always less expensive than |
| bicycles today. Track bicycles, however, which | | | | hydraulic) use regular brake cables and levers to |
| are ridden at top speed continuously, continue to | | | | actuate the pads. Hydraulic disc brakes use fluid |
| be built with no brakes; since they are fixed gear | | | | from a resevoir, pushed through a hose, to |
| bicycles, braking on these bikes is still achieved | | | | actuate the pistons in the disc caliper, that then |
| only by reversing the force on the pedals. This is | | | | actuate the pads. Hydraulic disc brakes |
| not a disadvantage for the very specialized | | | | occasionally require bleeding of the brake lines to |
| manner in which these bicycles are ridden. | | | | remove air bubbles. There are two types of |
| Types of bicycle brakes | | | | brake fluid used in disc brakes today: mineral oil |
| Rim brakes | | | | and DOT fluid. Mineral oil is generally inert and while |
| There are several types of rim brakes. In all of | | | | DOT has a higher boiling point, it is known to be |
| these designs, the braking force is applied by the | | | | corrosive to frame paint. The two are generally |
| rider squeezing a lever mounted on the handlebar; | | | | interchangeable as the different fluids may cause |
| this causes friction pads (usually made of leather | | | | seals to swell or be corroded |
| or rubber) to contact the rim of the rotating | | | | Many disc brakes have their two pads actuated |
| wheel, thus slowing it and the bicycle. | | | | from both sides of the caliper, while some (less |
| Rod brakes use a series of rods and pivots | | | | expensive in both hydraulic and mechanical |
| (rather than Bowden cables) to pull the friction | | | | varieties) have only one pad that moves. Many |
| pads upwards onto the inner surface (facing the | | | | hydraulic disc brakes have a self-adjusting |
| hub) of the wheel rim. They were often called | | | | mechanism so as the brake pad wears, the |
| "stirrup brakes" due to their shape. In order to fit | | | | pistons will keep the distance from the pad to the |
| the rear wheel as well as the more directly | | | | disc consistent in order to maintain the same |
| actuated front wheel, these brakes need a | | | | brake lever throw. Mechanical discs have a manual |
| mechanism to transmit the force but still allow | | | | adjuster to dial in the pad to rotor distance. |
| rotation where the fork attaches to the frame. | | | | Calipers are now generally made in one piece to |
| Although rod brakes are heavy and the linkage is | | | | increase stiffness and reduce the threat of leaks, |
| complex, they are reliable and durable and can be | | | | although the two piece design still reduces heat |
| repaired or adjusted with simple hand tools in | | | | builup more effectively than the one piece, and |
| areas where replacement Bowden cables are not | | | | most top end models still feature the 2 piece |
| available or are too expensive. They are still used | | | | caliper. |
| on some bicycles, typically roadsters, particularly in | | | | There are two standards for mounting disc brake |
| the Far East. | | | | calipers - IS (International Standard) and post |
| More modern designs use similar friction pads to | | | | mount. IS is the more common of the two. |
| squeeze the sides of the wheel rims, with the | | | | Manitou is the inventor of post mount. The |
| force transmitted to the brake from the lever by | | | | advantage of post mounting is that it's easier to |
| means of a Bowden cable. Designs include the | | | | align the caliper to the rotor since there is some |
| scissor-action "side pull" and "centre pull" brakes, | | | | allowable side to side adjustment. You must use |
| and the lever action "cantilever" and "V" brakes. | | | | spacers to properly align IS calipers. The |
| Single pivot side-pull caliper brakes are currently | | | | disadvantage to post mount is that the bolt is |
| used on the most inexpensive bikes, before the | | | | threaded directly into the fork lowers. If the |
| introduction of dual-pivot caliper brakes they were | | | | threading was stripped or if the bolt was stuck, |
| used on all types of road bicycles. They consist of | | | | then it would require purchasing new fork lowers. |
| two curved arms that cross at a pivot above the | | | | Frame manufacturers have standardized the IS |
| wheel and hold the brake pads on opposite sides | | | | mount for the rear disc brake mount. |
| of the rim. These arms have extensions on one | | | | There are two standards for disc hubs - IS and |
| side; the cable housing is attached to one | | | | centerlock. IS is a six-bolt mount and is the |
| extension and the inner cable to the other, so | | | | industry standard. Centerlock is patented by |
| that when the brake lever is squeezed, the arms | | | | Shimano and uses a splined interface along with a |
| move together and the brake pads squeeze the | | | | lockring to secure the disc. The advantages of |
| rim. These brakes are simple and effective when | | | | centerlock are that the splined interface is stiffer, |
| designed for relatively narrow tires, but have | | | | removing the disc is quicker because it only |
| serious disadvantages if made big enough to fit | | | | requires one lockring to be removed, and the |
| wide tires. The low quality varieties also have a | | | | hubs and discs are lighter than the 6 bolt ones. |
| tendency to rotate to one side during actuation | | | | The disadvantage is that the design is patented |
| and to stay there, so that one brake pad | | | | requiring a licensing fee from Shimano. |
| continually rubs the rim even when the brake is | | | | Advantages of IS six-bolt are that you have |
| released. | | | | more choices when it comes to hubs and rotors. |
| Center-pull caliper brakes in the past filled the price | | | | IS rotors use allen bolts or Torx bolts to secure |
| niche between the cheaper and the more | | | | them to the hub. This also makes IS rotors |
| expensive models of side-pull brakes, being | | | | harder to remove and the possiblity of stripping |
| reasonably priced but without the tendency of the | | | | the bolts and requiring a new hub. |
| cheaper sidepull brakes to have one brake pad | | | | The rotors come in several different sizes, |
| continually rub the rim. In this type of brake the | | | | generally six, seven, or eight in diameter. These |
| actuation of the two brake arms is designed to | | | | are the industry standard sizes, some prototype |
| be symmetrical. The cable housing is attached to | | | | versions are coming out with 9 in diameter rotors |
| a fixed cable stop attached to the frame, and the | | | | now. As the rotor size becomes bigger, so does |
| inner cable attaches to a sliding piece or | | | | the torque on the wheel resulting in a more |
| sometimes a small pulley, over which runs a | | | | powerful brake. Also for every revolution of the |
| straddle cable which connects the two brake | | | | wheel more area of the disc passes through the |
| arms. Thus tension on the cable is evenly | | | | caliper making the bigger rotors run cooler. If too |
| distributed to the two arms, preventing the brake | | | | small of a disc is run for your specific type of |
| from taking a "set" to one side or the other. | | | | riding, brake fade may be experienced because of |
| Dual-pivot caliper brakes are used on most | | | | the brake fluid boiling. |
| modern racing bicycles. The cable housing is | | | | Drum brakes |
| attached like that of a side-pull brake. Centering of | | | | Drum brakes are used mainly on bicycles which |
| side-pull brakes was simplified with the | | | | are operated in wet or dirty conditions. Though |
| mass-market adoption of dual-pivot side-pulls (an | | | | heavier, more complicated, and frequently weaker |
| old design re-discovered by Shimano in the early | | | | than rim brakes, they require much less |
| 1990s). These brakes also offer a higher | | | | maintenance and are less affected by road |
| mechanical advantage. Dual-pivot brakes have | | | | conditions. Both cable- and rod-operated drum |
| slightly higher weight than conventional side-pull | | | | brake systems have been widely produced. While |
| calipers and cannot accurately track an | | | | most common on utility bicycles in certain |
| out-of-true rim. One arm pivots at the center, like | | | | countries, especially the Netherlands, they are also |
| a side-pull; and the other pivots at the side, like a | | | | frequently found on freight bicycles. |
| center-pull. | | | | A bicycle drum brake's operation is identical to |
| Cantilever, direct-pull, and V-brakes have each | | | | that of a car's with the exception of the absence |
| arm attached to a separate pivot point on one | | | | of a ratching adjustment mechanism and hydraulic |
| side of the seat stay or fork just below the rim. | | | | actuation. Two pads are pressed outward against |
| The wider tires on mountain bikes present a | | | | the braking surface on the inside of the hub's shell, |
| problem with standard calipers because the long | | | | which is packed with grease. Shell diameters on a |
| distance from the pivot to the pad allows the | | | | bicycle drum brake are typically 70 - 120 mm. |
| arms to flex, reducing braking effectiveness. | | | | Drum brakes have been used on front hubs and |
| Cantilever brakes are one solution to this problem. | | | | hubs with both internal and external freewheels. |
| The traditional cantilever has an L-shaped arm | | | | A common design of drum brake is the Roller |
| protruding outwards on each side, with a cable | | | | Brake, manufactured by Shimano. This is a |
| stop on the frame or fork to hold the cable | | | | modular cable-operated drum brake for use on |
| housing and a straddle cable between the arms | | | | specially splined front and rear hubs. Unlike a |
| similar to the centerpull brake. The cable from the | | | | normal drum brake, the Roller Brake can be |
| brake handle pulls upwards on the straddle cable, | | | | removed entirely from a hub, allowing it to |
| causing the brake arms to rotate up and inward | | | | function as a regular freewheel. It also contains a |
| and squeezing the rim between the brake pads. | | | | torque limiting device which reduces its |
| V-brakes (sometimes called linear- or direct-pull) | | | | effectiveness on bicycles with adult-sized wheels. |
| mount similarly, but the arms extend straight up, | | | | Drag brake |
| and the outer housing is attached to one arm and | | | | In addition, drum brakes are also installed on some |
| the inner housing to the other, similar to the cable | | | | tandems used in mountainous areas as a so called |
| attachment for sidepull brakes. They are generally | | | | drag brake. In this application, the drum is not |
| more powerful and easier to adjust than | | | | intended to stop the bike but, rather, to keep the |
| cantilever brakes, and have the additional | | | | speed down on long downhill sections where |
| advantage of functioning well with the suspension | | | | extended use of rim brakes can cause the tire to |
| systems found on many mountain bikes because | | | | become hot enough to explode. |
| they are self contained and do not require a | | | | The largest manufacturer of this type is Arai, |
| separate cable stop. However due to their higher | | | | whose brakes are screwed onto hubs with |
| mechanical advantage, the brake pads must be | | | | conventional freewheel threading on the left side |
| positioned very close to the rim. Also see | | | | of the rear hub and operated via Bowden cables. |
| V-brake adjustment. | | | | Coaster brakes |
| Closely related is the U-brake; this type has the | | | | A coaster brake, also known as a back pedal |
| pivots for the arms mounted to the frame or | | | | brake or foot brake (or torpedo in some |
| fork on each side above the rim. The arms cross | | | | countries), is a drum brake integrated into hubs |
| over similarly to sidepull or centerpull brakes, and | | | | with an internal freewheel. Freewheeling functions |
| BMX bikes; its main advantage was that it did not | | | | as with other systems, but, when back pedalled, |
| protrude sideways from the frame like the early | | | | the brake engages after a fraction of a revolution. |
| cantilevers. This advantage was reduced by | | | | It can frequently be found in both single-speed |
| redesigned low-profile cantilevers, and nearly | | | | and geared hubs. |
| eliminated with V brakes. | | | | When such a hub is pedalled forwards, the |
| One of the least common rim brakes is the | | | | sprocket drives a screw which forces a clutch to |
| hydraulic rim brake. These brakes are generally | | | | move along the axle, driving the hub shell or gear |
| able to be mounted on the same pivot points | | | | assembly. When pedalling is reversed, the screw |
| used for cantilever and linear-pull brakes. They | | | | drives the clutch in the opposite direction, forcing |
| were available on some high-end mountain bikes in | | | | it either between two brake pads and pressing |
| the early 1990's, but declined in popularity with the | | | | them against the shell, or into a split collar and |
| rise of disk and linear-pull brakes. The moderate | | | | expanding it against the shell. The braking surface |
| performance advantage (greater power and | | | | is often steel, and the braking element brass or |
| control) they offer over the latter is offset by | | | | phosphor-bronze, as in the UK Birmingham made |
| their greater weight and complexity. The only | | | | Perry Coaster Hub. |
| significant current use of these brakes is on | | | | Coaster brake bicycles are generally equipped |
| bicycles used for trials riding. | | | | with a single cog and chainwheel and use a 1" |
| Another design is the delta brake. In this design, | | | | chain. However, there have been several models |
| the pivot points for the arms are above the rim | | | | of coaster brake hubs with derailleurs in the past, |
| but the arms do not cross over, and instead of a | | | | most notably the Sachs 2x3. These use special |
| straddle cable, the inner brake cable attaches to a | | | | extra-short derailleurs which both can stand up to |
| wedge shaped piece between the brake arms; | | | | the rigors of being straighted out frequently and |
| when the brakes are applied the wedge forces | | | | don't require an excessive amount of reverse |
| the arms apart at the top, squeezing the rim | | | | pedal rotation before the brake engages. |
| between the pads. This has an advantage in that | | | | Although coaster brakes have the advantage of |
| the shape of the wedge can be varied other than | | | | being protected from the elements and thus |
| straight-sided, to allow for a very high mechanical | | | | immune to ice or water, because they are |
| advantage at the point where the pads contact | | | | located in the rear wheel only limited braking force |
| the rim to give high braking power, but a lower | | | | can be applied before the rear wheel locks up. |
| mechanical advantage when the pads are not | | | | This is due to the placement of the rider's weight |
| contacting the rim so that the pads move well | | | | ahead of the rear tyre's contact with the ground, |
| away from the rim when the brake is not applied, | | | | as well as the weight transfer forward |
| preventing any rubbing. | | | | proportional to braking force, which further |
| The advantages of rim brakes are that they are | | | | unloads the rear wheel. Additionally, although |
| inexpensive, lightweight, mechanically simple, and | | | | coaster brakes generally go years without needing |
| easy to maintain, as well as very powerful. The | | | | maintenance, they are more complicated than rim |
| main disadvantage of rim brakes is that their | | | | brakes to repair if it becomes necessary. |
| performance deteriorates in wet weather when | | | | Spoon brakes |
| the rims are wet. This problem is less serious on | | | | The spoon brake was one of the first types of |
| more expensive bikes which use rims made of | | | | bicycle brakes and precedes the pneumatic tire. |
| aluminum alloys than on those with steel rims. | | | | They were first used on penny farthings with |
| They are also prone to clogging with mud, | | | | solid rubber tires in the late 1800's and continued |
| particularly when mountain biking. Rim brakes also | | | | to be used after the introduction of the |
| need regular maintenance. Brake pads wear down | | | | pneumatic tired safety bicycle. It consists of a |
| quickly, and have to be replaced. Over long | | | | pad (often leather) which is pressed onto the top |
| periods of time and use, rims also become worn. | | | | of the front tire. These were almost always |
| Bowden cables can jam if not regularly lubricated | | | | rod-operated by a right-hand lever. In developing |
| or if water gets into the housing, causing | | | | countries, a foot-operated form of the spoon |
| corrosion. The cables also wear, requiring frequent | | | | brake is sometimes retrofitted to old rod brake |
| checking and replacement. If the inner cables are | | | | roadsters. It consists of a spring-loaded flap |
| not replaced when they fray, they will suddenly | | | | attached to the back of the fork crown. This is |
| break when brakes are applied strongly, causing | | | | depressed against the front tire by the rider's |
| brakes to be lost precisely when they are most | | | | foot. |
| needed. Rim brakes also require that the rim be | | | | Perhaps more so than any other form of bicycle |
| relatively true; if the rim has a pronounced | | | | brake, the spoon brake is very sensitive to road |
| wobble, either side to side or inwards and | | | | conditions and increases tire wear dramatically. |
| outwards, it will be impossible to adjust the brake | | | | Though made obsolete by the introduction of the |
| pads so that they can apply sufficient pressure to | | | | coaster brake and rod brake, they continued to |
| the rim but do not rub when released and do not | | | | be used supplementally on adult bicycles until the |
| contact the tire, which would lead to a rapid | | | | 1930's and children's bicycles until the 1950's, in the |
| blowout. | | | | West. In the developing world, they were |
| Rim brakes also suffer from the disadvantage of | | | | manufactured until much more recently. |
| rim heating, because the brake converts kinetic | | | | Braking technique |
| energy into heat, which increases the | | | | Effective use of a bicycle brake is highly |
| temperature of the rim (the brake caliper and | | | | counter-intuitive. The casual rider will at first avoid |
| frame do not become hot because brake pads | | | | using the front brake, due to the unsettling feeling |
| are excellent thermal insulators). In normal use and | | | | of "toppling up", or fear of being sent flying over |
| with lightweight bicycles this does not present a | | | | the handlebars. |
| problem as the brakes are only applied with a | | | | However, the most effective technique for |
| limited force and for a short time, with the heat | | | | powerful stopping is to use the front brake |
| being quickly disspated to the surrounding air. | | | | almost exclusively. There are several exceptions |
| However, on heavily-laden touring bikes and | | | | where the rear brake is preferred; these are |
| tandems in mountainous regions the heat build-up | | | | listed below. In any stop, the rider should shift |
| can be sufficient to increase tire pressure to the | | | | their weight toward the rear and use their arms |
| extent that the tire blows off the rim. If this | | | | to brace against the deceleration. |
| happens on the front wheel a serious accident is | | | | During braking (either with the front or rear |
| almost inevitable. The problem is worse when | | | | brake), the bike deceleration causes a transfer of |
| descending cautiously at slow speeds because the | | | | weight to the front wheel. This means that there |
| brakes are "always on" and the cooling airflow | | | | is more force pressing the front wheel to the |
| over the rim is insufficient. The risk can be | | | | ground, and the back wheel nearly none. |
| minimised by not over-inflating tires and the | | | | Therefore, the front wheel can generate more |
| adoption of an aggressive riding style, only braking | | | | frictional braking force than the back wheel |
| for the corners, but the real solution is a hub | | | | before locking up and skidding. In any conditions |
| brake or a disc brake which allows the rim to | | | | and especially in wet conditions or going downhill, |
| remain cool. | | | | the rear brake can exert relatively little braking |
| Brake pads (brake blocks) are of many designs. | | | | force before the wheel locks and starts skidding. |
| Most consist of a replaceable rubber pad held in a | | | | For a more-detailed analysis, see Bicycle and |
| metal channel (brake shoe), with a post or bolt | | | | motorcycle dynamics. |
| protruding from the back to allow attachment to | | | | A skidding rear wheel can lead to dangerous, |
| the brake, but some are made as one piece with | | | | uncontrollable bicycle movements eventually |
| the attachment directly moulded in the pad for | | | | resulting in the cyclist falling on the ground. A key |
| lower production costs. The rubber can be softer | | | | scenario for this is "light" braking on rapid |
| for more braking force with less lever effort, or | | | | alpine-type hairpin (serpentine) descents; further |
| harder for longer life. The rubber can also contain | | | | attenuation of speed to negotiate a decrease in |
| abrasives for better braking, at the expense of | | | | curve radius (tightening of the bend in the road) |
| rim wear. Compounds vie for better wet braking | | | | can be executed successfully while pulling through |
| efficiency. Typically pads are relatively short, but | | | | a tight corner regulating with the front brake only. |
| longer varieties are also manufactured to provide | | | | In an emergency stop, it is important to grab the |
| more surface area for braking; these often must | | | | front brake and press it hard to stop in the |
| be curved to match the rim. It should be noted | | | | minimum possible distance. The rider should shift |
| that a larger pad does not give more friction, but | | | | his or her weight as far to the rear as possible to |
| it does wear more slowly and therefore a new | | | | avoid flipping over the handlebars. Maximum |
| pad can be made thinner, simplifying wheel | | | | deceleration is accomplished by maintaining enough |
| removal with V-brakes in particular. In general, a | | | | pressure on the front brake such that that the |
| brake can be fitted with any of these many | | | | rear wheel is barely touching the ground, just |
| varieties of pads, so long as the pad mounting | | | | before lifting up. In reality this is not practical for |
| method is compatible. Carbon rims, as on some | | | | most cyclists. Instead, use light pressure on the |
| disc wheels, generally have to use non-abrasive | | | | back wheel and hard pressure on the front. The |
| cork pads. | | | | back wheel is primarily useful as an |
| Disc brakes | | | | indicator—when it starts to skid, reduce |
| Disc brakes consist of a metal disc attached to | | | | the pressure to both brakes to prevent the rear |
| the wheel hub that rotates with the wheel. | | | | wheel from lifting, then increase pressure to both |
| Calipers are attached to the frame or fork along | | | | again. |
| with pads that squeeze together on the disc. | | | | Incidentally, on tandems, and long-wheel-base |
| Although these brake types have been | | | | recumbents with their long wheelbase and center |
| successfully used on, and have been the principal | | | | of mass farther from the front wheel, it is |
| choice for motorbikes for decades, numerous | | | | virtually impossible for heavy front braking to |
| (partly successful) attempts at introducing disc | | | | cause the machine to flip. |
| brakes for bicycles over the last decades [citation | | | | There are a few special situations where limited |
| needed] may now finally have reached fruition. | | | | use of the front brake, and heavier involvement |
| Recent weight/costs/reliability material advances | | | | of the rear brake is advisable: |
| have led to development and implementation of | | | | Slippery surfaces: It is difficult to recover from a |
| disc brake systems by several firms to the | | | | front-wheel skid on a slippery surface, especially |
| extent that they are becoming a standard | | | | when leaned over, so on surfaces when skidding |
| feature on many bicycles, and are almost | | | | is likely (e.g. wet pavement, mud, snow, or ice), |
| certainly here to stay. Disc brakes are most | | | | reduced speed and use of the rear brake may be |
| suitable for and used mainly on mountain bikes | | | | preferred. |
| ridden off-road. They also are used on hybrid | | | | Bumpy surfaces: If the front wheel comes off of |
| bicycles and some road bicycles, although this is | | | | the ground during braking, it will stop completely. |
| less common. Many tandem bicycles have a disc | | | | Landing on a stopped front wheel with the brakes |
| brake fitted on the rear wheel in addition to rim | | | | still applied is likely to cause the front wheel to |
| brakes; the disc brake can be set to provide a | | | | skid and, possibly, for the rider to flip over the |
| constant drag, so that during long descents, the | | | | front bars. |
| rim brakes are not overworked by the heavier | | | | Flat front tire: Braking the front wheel when the |
| machine.[citation needed] | | | | tire is flat could cause the tire to come off of the |
| The main advantage of disc brakes is that their | | | | rim, which is more likely to cause a crash. |
| performance is equally good in all conditions | | | | |