Bowden cable
Encyclopedia
A Bowden cable
is a type of flexible cable
used to transmit mechanical
force
or energy
by the movement of an inner cable (most commonly of steel
or stainless steel
) relative to a hollow outer cable housing. The housing is generally of composite construction, consisting of a helical
steel wire, often lined with plastic
, and with a plastic outer sheath.
The linear movement of the inner cable is generally used to transmit a pulling force, although for very light applications over shorter distances (such as the remote shutter release cables on mechanical film cameras) a push may also be used. Usually provision is made for adjusting the cable tension using an inline hollow bolt
(often called a "barrel adjuster"), which lengthens or shortens the cable housing relative to a fixed anchor point. Lengthening the housing (turning the barrel adjuster out) tightens the cable; shortening the housing (turning the barrel adjuster in) loosens the cable.
The invention of the Bowden cable has been popularly attributed to Sir Frank Bowden, founder and owner of the Raleigh Bicycle Company
who, circa 1902, was reputed to have started replacing the rigid rods used for brakes with a flexible wound cable. There appears to be no current definitive reference for this.
The Bowden mechanism was invented by Irishman Ernest Monnington Bowden
(1860 to April 3, 1904) of 35 Bedford Place, London, W.C. The first patent was granted in 1896. (English Patent 25,325 and U.S. Pat. No. 609,570). The principal element of this was a flexible tube (made from hard wound wire and fixed at each end) containing a length of fine wire rope that could slide within the tube, directly transmitting pulling, pushing or turning movements on the wire rope from one end to the other without the need of pulleys or flexible joints. The cable was particularly intended for use in conjunction with bicycle brakes, although it had the potential for other applications. The Bowden Brake was launched amidst a flurry of enthusiasm in the cycle press in 1896. It consisted of a stirrup, pulled up by the cable from a handlebar mounted lever, with rubber pads acting against the rear wheel rim. At this date bicycles were fixed wheel, additional braking being offered by a 'plunger' brake pressing on the front tyre. The Bowden offered extra braking power still, and was novel enough to appeal to riders who scorned the plunger arrangement, which was heavy and potentially damaging to the (expensive) pneumatic tyre. The problem for Bowden was his failure to develop effective distribution networks and the brake was often incorrectly, or inappropriately fitted, resulting in a good number of complaints being aired in the press. Its most effective application was on those machines fitted with Westwood pattern steel rims which offered flat bearing surfaces for the brake pads.
The potential of the Bowden cable and associated brake was not to be fully realised until the free-wheel sprocket became a standard feature of bicycles, over the period 1899-1901, and increasing numbers of applications were found for it, such as gear change mechanisms. Importantly in 1903, Hendee developed the twist-grip throttle using a similar cable for his 'Indian' motorcycles. Its lightness and flexibility recommended it to further automotive use such as clutch and speedometer drive cables.
It is reported that "on 12th January 1900 E. M. Bowden granted a licence to The Raleigh Cycle Company of Nottingham", whose directors were Frank Bowden and Edward Harlow. At this signing they became members of 'E. M. Bowden's Patent Syndicate Limited'. The syndicate included, among others, R. H. Lea & Graham I. Francis of Lea & Francis Ltd, and William Riley of the Riley Cycle Company. The Raleigh company were soon offering the Bowden Brake as an accessory, and were quick to incorporate the cable into handlebar mounted Sturmey Archer (in which they had a major interest) gear changes. Undoubtedly this is why E. Bowden and F. Bowden are sometimes confused today.
An unpublished typescript exists in the archives of the National Motor Museum, written by the son of one of Bowden's employees that attempts to claim the invention of the cable for his father to the point of suggesting that it was never applied to bicycles before 1902. Although this is easily disproved by reference to 'Cycling' or the other UK cycle press through 1896-7, it serves to remind one of the attempts made to rewrite cycle history through priority claims. British
National Archives In this narrative a flexible cable brake for cycles was separately 'invented' by George Frederick Larkin, a skilled automobile and motorcycle engineer, who patented his design in 1902. He was subsequently recruited by, and worked for E.M. Bowden until 1917 as General Works Manager.
Early Bowden cable, from the 1890s and first years of the twentieth century, is characterised by the outer tube being wound from round wire and being uncovered. Each length is usually fitted with a brass collar marked 'BOWDEN PATENT', (this legend is also stamped into the original brake's components). More modern outer tube is wound from square section wire. From c1902 the cable was usually covered in a waterproof fabric sheaf, in the early post war period this gave way to plastic.
In order to support indexed shifting, Shimano
developed a type of housing that does not change length as it is flexed. This housing has several wire strands running in a multiple helix, with a pitch short enough that bends in the cable are shared by all strands, but long enough that the housing's flexibility comes by bending the individual strands rather than twisting them. Another consequence of the long pitch of the helix is that the essentially parallel strands are only bound together by the plastic jacket, and so this type of housing cannot withstand high tension in the inner cable which causes high compression in the housing and can result in failure by buckling
of the housing strands. This type of housing should not be used for brake cables.
A third type of housing consists of short hollow rigid aluminum or carbon fiber
cylinders slid over a flexible liner. Claimed benefits over steel wire housing include less weight, tighter curves, and less compression under load.
s for push applications have an additional winding that runs in the opposite direction to the wind of the actual inner wire. The wind may be like that of a spring or a wind with a flat strip; these are called spring wrap and spiral wrap respectively.
Some applications such as lawn mower throttles, automobile manual choke
s, and some bicycle shifting systems require significant pushing ability and so use a cable with a solid inner wire. These cables are usually less flexible than ones with stranded inner wires.
Traditionally, in bicycle applications, shifter cables have a small cylindrical nipple concentric with the cable, while brake cables have a larger, barrel (cylindrical) nipple whose center axis is perpendicular to the cable axis. Some replacement cables come with both styles, one on each end. The unneeded end is to be cut off and discarded upon installation.
In bicycle applications, for both brakes and gear-shifting, the cap or ferrule that tight-terminates the housing, makes a loose fit within the barrel-adjuster end. In this way the barrel will slip on the ferrule as it is turned. If the ferrule were to be jammed into the barrel end, then the cable would twist during fruitless attempts at adjustment.
Nipples are also available separately from the cable, for purposes of repair or custom cable construction. They are fitted to the cable by soldering
. Where free rotation of nipples, relative to the cable axis is required, the cable end may be finished with a brass ferrule or "trumpet" soldered to the cable. The barrel nipple will be a sliding fit over the brass ferrule, and can thus rotate, to ensure alignment of the nipples at each end of the cable, and avoidance of twisting of the inner cable. Applying heat to the inner cable for soldering may weaken the steel, and although soft soldering is less strong than silver solder, a lower temperature is required to form the joint, and there is less likelihood of the inner cable being damaged as a result. Silver soldering may require additional heat treatment
of the wire to preserve the temper of it in order to prevent it from becoming too soft or too brittle
Nipples that clamp to the cable by means of a screw also are available for emergency repair purposes, or where removal is required for maintenance.
A small ferrule, also called a crimp, (seen in the rear derailleur picture) may be crimped on to prevent cable ends from fraying.
Other methods to prevent fraying include soft or silver soldering the wire ends, or ideally by flash cutting the wires.
If the inner wire is solid, as in automotive and lawnmower throttle and choke applications, it may simply have a bend at one or both ends to engage what ever it pushes or pulls.
, called donuts, can be threaded onto a bare run of the inner cable to prevent it from striking the bicycle frame causing rattles or abrasion.
Housings for bicycle brakes need not be quite so compressionless, and items currently sold for this purpose use a spirally wound support wire. These spirally wound items are stronger than the longitudinally reinforced housings used for shifting gears. One end of a brake housing is tight-terminated in an end cap or ferrule that makes a loose fit within a barrel adjuster, and the other in any of a variety of fittings that includes end caps, or parts to effect a smooth change of direction. In any case, at the point where the cable emerges for attachment to the brake arms, is fitted a nipple. In view of the wide array of cable constructions on offer, confusion as to the best housing can easily result. In general, a housing sold for one purpose should not be used for any other, and in any case the advice of the manufacturer should be followed. In particular, longitudinally reinforced housings should not be used for bicycle brakes, since they are weaker than the spirally wound housings. Spirally wound housings however, have poorer compression qualities than the longitudinally reinforced items so they should not be used for the shifting of gears.
Although the individual parts for cable assembly can be acquired, ready-made cables for both brakes and shifting are to be had. These usually consist of an inner wire within a length of housing, and depending on their purpose, with one or more end caps fitted. However, because of the wide range of fittings in use, it is probable that these universal cables' caps, although suiting many situations, will not suit every purpose, as their name wrongly implies. The shortening of housings requires the use of a special hand tool, designed to make a square cut without closing the cable entry. The same tool is used to cut the internal steel cable. To avoid unraveling of the cable's wires during installation, manufacturers weld the ends.
Housings for cables have habitually been made only in black, though some colored housings can also be found.
The specifications for cables and housings rarely give any details other than dimensions and the purpose of the products. The specific resistance to compression or bending is never quoted, so there is much rhetorical evidence and comment as to the performance and durability of products, but little available science for the consumer's use. A particularly severe quality test for housings is at or near the hinge of a folding bicycle where a sharp bend is made repeatedly. The radius of curvature of cables on a folded bicycle can be as low as 1.5 inches, (4 cm.), so it is as well to shift to the gear with the lowest cable pressure before folding, to minimize any adverse effects on housings or derailleurs. This gear is usually the one with the highest index number on the gear shifter.
There is some controversy surrounding the existence of the phenomenon known as "cable stretch". Newly installed cables can seem to elongate, requiring readjustment. While it is generally agreed that inner wires actually stretch very little - if at all - housings and linings may compress slightly, and all parts may generally "settle in". Lightweight assemblies such as those used on bicycles are more susceptible to this phenomenon.
is a type of flexible cable
Cable
A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...
used to transmit mechanical
Mechanics
Mechanics is the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment....
force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
or energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
by the movement of an inner cable (most commonly of steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
or stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
) relative to a hollow outer cable housing. The housing is generally of composite construction, consisting of a helical
Helix
A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...
steel wire, often lined with plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
, and with a plastic outer sheath.
The linear movement of the inner cable is generally used to transmit a pulling force, although for very light applications over shorter distances (such as the remote shutter release cables on mechanical film cameras) a push may also be used. Usually provision is made for adjusting the cable tension using an inline hollow bolt
Screw thread
A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread...
(often called a "barrel adjuster"), which lengthens or shortens the cable housing relative to a fixed anchor point. Lengthening the housing (turning the barrel adjuster out) tightens the cable; shortening the housing (turning the barrel adjuster in) loosens the cable.
History
The origin and invention of the Bowden Cable is open to some dispute, confusion and popular myth.The invention of the Bowden cable has been popularly attributed to Sir Frank Bowden, founder and owner of the Raleigh Bicycle Company
Raleigh Bicycle Company
The Raleigh Bicycle Company is a bicycle manufacturer originally based in Nottingham, UK. It is one of the oldest bicycle companies in the world. From 1921 to 1935 Raleigh also produced motorcycles and three-wheel cars, leading to the formation of the Reliant Company.-Early years:Raleigh's history...
who, circa 1902, was reputed to have started replacing the rigid rods used for brakes with a flexible wound cable. There appears to be no current definitive reference for this.
The Bowden mechanism was invented by Irishman Ernest Monnington Bowden
Ernest Monnington Bowden
Ernest Monnington Bowden was an Irishman who invented the Bowden mechanism.He lived at 35 Bedford Place, London, W.C. His first patent was granted in 1896...
(1860 to April 3, 1904) of 35 Bedford Place, London, W.C. The first patent was granted in 1896. (English Patent 25,325 and U.S. Pat. No. 609,570). The principal element of this was a flexible tube (made from hard wound wire and fixed at each end) containing a length of fine wire rope that could slide within the tube, directly transmitting pulling, pushing or turning movements on the wire rope from one end to the other without the need of pulleys or flexible joints. The cable was particularly intended for use in conjunction with bicycle brakes, although it had the potential for other applications. The Bowden Brake was launched amidst a flurry of enthusiasm in the cycle press in 1896. It consisted of a stirrup, pulled up by the cable from a handlebar mounted lever, with rubber pads acting against the rear wheel rim. At this date bicycles were fixed wheel, additional braking being offered by a 'plunger' brake pressing on the front tyre. The Bowden offered extra braking power still, and was novel enough to appeal to riders who scorned the plunger arrangement, which was heavy and potentially damaging to the (expensive) pneumatic tyre. The problem for Bowden was his failure to develop effective distribution networks and the brake was often incorrectly, or inappropriately fitted, resulting in a good number of complaints being aired in the press. Its most effective application was on those machines fitted with Westwood pattern steel rims which offered flat bearing surfaces for the brake pads.
The potential of the Bowden cable and associated brake was not to be fully realised until the free-wheel sprocket became a standard feature of bicycles, over the period 1899-1901, and increasing numbers of applications were found for it, such as gear change mechanisms. Importantly in 1903, Hendee developed the twist-grip throttle using a similar cable for his 'Indian' motorcycles. Its lightness and flexibility recommended it to further automotive use such as clutch and speedometer drive cables.
It is reported that "on 12th January 1900 E. M. Bowden granted a licence to The Raleigh Cycle Company of Nottingham", whose directors were Frank Bowden and Edward Harlow. At this signing they became members of 'E. M. Bowden's Patent Syndicate Limited'. The syndicate included, among others, R. H. Lea & Graham I. Francis of Lea & Francis Ltd, and William Riley of the Riley Cycle Company. The Raleigh company were soon offering the Bowden Brake as an accessory, and were quick to incorporate the cable into handlebar mounted Sturmey Archer (in which they had a major interest) gear changes. Undoubtedly this is why E. Bowden and F. Bowden are sometimes confused today.
An unpublished typescript exists in the archives of the National Motor Museum, written by the son of one of Bowden's employees that attempts to claim the invention of the cable for his father to the point of suggesting that it was never applied to bicycles before 1902. Although this is easily disproved by reference to 'Cycling' or the other UK cycle press through 1896-7, it serves to remind one of the attempts made to rewrite cycle history through priority claims. British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
National Archives In this narrative a flexible cable brake for cycles was separately 'invented' by George Frederick Larkin, a skilled automobile and motorcycle engineer, who patented his design in 1902. He was subsequently recruited by, and worked for E.M. Bowden until 1917 as General Works Manager.
George Larkin is known for his invention of the flexible cable brake for cycles, which was patented in 1902. The original patent for a similar invention known as the 'Bowden mechanism' was granted to Ernest Monnington Bowden in 1896. The following year E.M. Bowden's Patents Syndicate Ltd. was formed to market the device but initially the project was a failure because all the company could offer was a flimsy mechanism capable of transmitting comparatively enormous power. The Bowden Mechanism was not developed in connection with a cycle brake as there is no record of the cable having been associated with the cycle industry until 1902, when George Larkin's invention was patented.
During Larkin's employment with Bassett Motor Syndicate his duties included the assembly of motor cars and motor cycles, and a major difficulty was the assembly of the braking systems which at that time comprised steel rods, not easily adaptable to the contour of the chassis. He designed a flexible cable brake and approached S.J. Withers, Patent Agent, to have the design patented. Withers noticed the similarity of Larkin's idea to the Bowden Mechanism and introduced him to the Bowden Syndicate, who agreed to manufacture and market the invention with the proviso that it should be patented jointly in the names of the inventor and themselves. Within a few months, Larkin, then aged 23, was engaged as Motor Department Manager with E.M. Bowden's Patents Syndicate, and he was appointed General Works Manager on 1 May 1904.
Early Bowden cable, from the 1890s and first years of the twentieth century, is characterised by the outer tube being wound from round wire and being uncovered. Each length is usually fitted with a brass collar marked 'BOWDEN PATENT', (this legend is also stamped into the original brake's components). More modern outer tube is wound from square section wire. From c1902 the cable was usually covered in a waterproof fabric sheaf, in the early post war period this gave way to plastic.
Parts and variations
Housing
The original, standard Bowden cable housing consists of a close-wound helix of round or square steel wire. This makes a flexible housing but causes the length to change as the housing flexes. Because on the inside of the bend the turns of a close-wound helix can't get any closer together, the bending causes the turns to separate on the outside of the bend, and so at the centerline of the housing, there must also be an increase of length with increasing bend.In order to support indexed shifting, Shimano
Shimano
Shimano, Inc. is a Japanese multinational manufacturer of cycling components, fishing tackle, and rowing equipment.In 2005, the company had net sales of US $1.4 billion. Bicycle components provided 75% of its sales income...
developed a type of housing that does not change length as it is flexed. This housing has several wire strands running in a multiple helix, with a pitch short enough that bends in the cable are shared by all strands, but long enough that the housing's flexibility comes by bending the individual strands rather than twisting them. Another consequence of the long pitch of the helix is that the essentially parallel strands are only bound together by the plastic jacket, and so this type of housing cannot withstand high tension in the inner cable which causes high compression in the housing and can result in failure by buckling
Buckling
In science, buckling is a mathematical instability, leading to a failure mode.Theoretically, buckling is caused by a bifurcation in the solution to the equations of static equilibrium...
of the housing strands. This type of housing should not be used for brake cables.
A third type of housing consists of short hollow rigid aluminum or carbon fiber
Carbon fiber
Carbon fiber, alternatively graphite fiber, carbon graphite or CF, is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in crystals that are more or less aligned parallel to the long axis of the fiber...
cylinders slid over a flexible liner. Claimed benefits over steel wire housing include less weight, tighter curves, and less compression under load.
Inner wire
Inner wire ropeWire rope
thumb|Steel wire rope Wire rope is a type of rope which consists of several strands of metal wire laid into a helix. Initially wrought iron wires were used, but today steel is the main material used for wire ropes....
s for push applications have an additional winding that runs in the opposite direction to the wind of the actual inner wire. The wind may be like that of a spring or a wind with a flat strip; these are called spring wrap and spiral wrap respectively.
Some applications such as lawn mower throttles, automobile manual choke
Choke valve
A Choke valve is a type of valve designed to create choked flow in a fluid. Over a wide range of valve settings the flow through the valve can be understood by ignoring the viscosity of the fluid passing through the valve; the rate of flow is determined only by the ambient pressure on the upstream...
s, and some bicycle shifting systems require significant pushing ability and so use a cable with a solid inner wire. These cables are usually less flexible than ones with stranded inner wires.
Ends
One end of the inner cable may have a small shaped piece of metal, known (from the pear-shaped soldered terminations used in some cases) as a nipple (as can be seen in the BMX rear brake detangler picture) that fits into a shifter or brake lever mechanism. The other end is often clamped (as can be seen in the rear derailleur picture) to the part of the brake or shifter that needs to be moved, or as is most common with motorcycle control cables, fitted with another nipple.Traditionally, in bicycle applications, shifter cables have a small cylindrical nipple concentric with the cable, while brake cables have a larger, barrel (cylindrical) nipple whose center axis is perpendicular to the cable axis. Some replacement cables come with both styles, one on each end. The unneeded end is to be cut off and discarded upon installation.
In bicycle applications, for both brakes and gear-shifting, the cap or ferrule that tight-terminates the housing, makes a loose fit within the barrel-adjuster end. In this way the barrel will slip on the ferrule as it is turned. If the ferrule were to be jammed into the barrel end, then the cable would twist during fruitless attempts at adjustment.
Nipples are also available separately from the cable, for purposes of repair or custom cable construction. They are fitted to the cable by soldering
Soldering
Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the workpiece...
. Where free rotation of nipples, relative to the cable axis is required, the cable end may be finished with a brass ferrule or "trumpet" soldered to the cable. The barrel nipple will be a sliding fit over the brass ferrule, and can thus rotate, to ensure alignment of the nipples at each end of the cable, and avoidance of twisting of the inner cable. Applying heat to the inner cable for soldering may weaken the steel, and although soft soldering is less strong than silver solder, a lower temperature is required to form the joint, and there is less likelihood of the inner cable being damaged as a result. Silver soldering may require additional heat treatment
Heat treatment
Heat treating is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass...
of the wire to preserve the temper of it in order to prevent it from becoming too soft or too brittle
Nipples that clamp to the cable by means of a screw also are available for emergency repair purposes, or where removal is required for maintenance.
A small ferrule, also called a crimp, (seen in the rear derailleur picture) may be crimped on to prevent cable ends from fraying.
Other methods to prevent fraying include soft or silver soldering the wire ends, or ideally by flash cutting the wires.
If the inner wire is solid, as in automotive and lawnmower throttle and choke applications, it may simply have a bend at one or both ends to engage what ever it pushes or pulls.
Donuts
Small rubber toriTorus
In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...
, called donuts, can be threaded onto a bare run of the inner cable to prevent it from striking the bicycle frame causing rattles or abrasion.
Common practice
The indexed shifting of a bicycle derailleur needs to be exact. A typical 7-speed shifter changes the cable length by either 2.9mm (Shimano 2:1) or 4.5mm (SRAM 1:1) for each shift, and any length errors accumulate with the number of shifts. To this end, the housing needs to behave as if it were a solid tube, so it, and its end-pieces have to be compressionless. Currently, the most commonly used compressionless housing for gear shifting has longitudinally spaced steel wires. The flat-cut ends of such housing are tight-terminated with end caps or ferrules, and the ends caps are sized to fit either into a fixture on the frame, or as a loose fitting in the end of a barrel adjuster.Housings for bicycle brakes need not be quite so compressionless, and items currently sold for this purpose use a spirally wound support wire. These spirally wound items are stronger than the longitudinally reinforced housings used for shifting gears. One end of a brake housing is tight-terminated in an end cap or ferrule that makes a loose fit within a barrel adjuster, and the other in any of a variety of fittings that includes end caps, or parts to effect a smooth change of direction. In any case, at the point where the cable emerges for attachment to the brake arms, is fitted a nipple. In view of the wide array of cable constructions on offer, confusion as to the best housing can easily result. In general, a housing sold for one purpose should not be used for any other, and in any case the advice of the manufacturer should be followed. In particular, longitudinally reinforced housings should not be used for bicycle brakes, since they are weaker than the spirally wound housings. Spirally wound housings however, have poorer compression qualities than the longitudinally reinforced items so they should not be used for the shifting of gears.
Although the individual parts for cable assembly can be acquired, ready-made cables for both brakes and shifting are to be had. These usually consist of an inner wire within a length of housing, and depending on their purpose, with one or more end caps fitted. However, because of the wide range of fittings in use, it is probable that these universal cables' caps, although suiting many situations, will not suit every purpose, as their name wrongly implies. The shortening of housings requires the use of a special hand tool, designed to make a square cut without closing the cable entry. The same tool is used to cut the internal steel cable. To avoid unraveling of the cable's wires during installation, manufacturers weld the ends.
Housings for cables have habitually been made only in black, though some colored housings can also be found.
Maintenance
Bowden cables can cease to function smoothly, particularly if water or contaminants get into the housing. (Modern lined and stainless steel cables are less prone to these problems; unlined housings should be lubricated with a light machine oil.) Cables also wear through repeated use over a long time, and can be damaged through kinking or raveling. A common failure occurs on bicycles at the point where the housing enters a barrel adjuster; loose housing ends tend to fray the housing, making adjustments uncertain. Fraying due to fatigue is most likely if the cable passes over a pulley, which on bicycles is often below the recommended diameter, or where the cable is bent repeatedly where it attaches to the brake lever or caliper. Sharp bends tend to furrow the inner cable sleeves, though its significance for gear shifting and braking is poorly documented. If an inner cable is not replaced when it frays, it can suddenly break when force is applied strongly, causing the link to fail when most needed (e.g. to a brake).The specifications for cables and housings rarely give any details other than dimensions and the purpose of the products. The specific resistance to compression or bending is never quoted, so there is much rhetorical evidence and comment as to the performance and durability of products, but little available science for the consumer's use. A particularly severe quality test for housings is at or near the hinge of a folding bicycle where a sharp bend is made repeatedly. The radius of curvature of cables on a folded bicycle can be as low as 1.5 inches, (4 cm.), so it is as well to shift to the gear with the lowest cable pressure before folding, to minimize any adverse effects on housings or derailleurs. This gear is usually the one with the highest index number on the gear shifter.
There is some controversy surrounding the existence of the phenomenon known as "cable stretch". Newly installed cables can seem to elongate, requiring readjustment. While it is generally agreed that inner wires actually stretch very little - if at all - housings and linings may compress slightly, and all parts may generally "settle in". Lightweight assemblies such as those used on bicycles are more susceptible to this phenomenon.
Uses
- sustain pedalSustain pedalA sustain pedal or sustaining pedal is the most commonly used pedal in a modern piano. It is typically the rightmost of two or three pedals. When pressed, the sustain pedal "sustains" all the damped strings on the piano by moving all the dampers away from the strings and allowing them to vibrate...
linkage on Wurlitzer electric pianoWurlitzer electric pianoWurlitzer 200A|250px|thumbThe Wurlitzer electric piano was one of a series of electromechanical stringless pianos manufactured and marketed by the Rudolph Wurlitzer Company, Corinth, Mississippi, U.S. and Tonawanda, New York...
s - bicycle brakeBicycle brake systemsA bicycle brake is used to slow down or stop a bicycle. There have been various types of brake used throughout history, and several are still in use today...
and gear shiftBicycle gearingA bicycle gear or gear ratio refers to the rate at which the rider's legs turn compared to the rate at which the wheels turn. Bicycle gearing refers to how the gear ratio is set or changed. On some bicycles, there is only one gear so the ratio is fixed. Most modern bicycles have multiple gears,...
cables - photographicPhotographyPhotography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...
shutterShutter (photography)In photography, a shutter is a device that allows light to pass for a determined period of time, for the purpose of exposing photographic film or a light-sensitive electronic sensor to light to capture a permanent image of a scene...
release cables - automotiveAutomobileAn automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
clutchClutchA clutch is a mechanical device which provides for the transmission of power from one component to another...
, throttleThrottleA throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases , but usually decreased. The term throttle has come to refer, informally and incorrectly, to any mechanism by which...
/cruise controlCruise controlCruise control is a system that automatically controls the speed of a motor vehicle. The system takes over the throttle of the car to maintain a steady speed as set by the driver.-History:...
, emergency brakeHand brakeIn cars, the hand brake is a latching brake usually used to keep the car stationary, and in manual transmission vehicles, as an aid to starting the vehicle from stopped when going up an incline - with one foot on the clutch , the other on the accelerator In cars, the hand brake (emergency brake,...
, and various latchLatch (hardware)A latch is a type of mechanical fastener that is used to join two objects or surfaces together while allowing for the regular or eventual separation of the objects or surfaces....
release cables - aircraft engineAircraft engineAn aircraft engine is the component of the propulsion system for an aircraft that generates mechanical power. Aircraft engines are almost always either lightweight piston engines or gas turbines...
controls including throttle or power control, propeller pitch or RPM, fuel mixture, carburetor heat, and cowl flaps - motorcycleMotorcycleA motorcycle is a single-track, two-wheeled motor vehicle. Motorcycles vary considerably depending on the task for which they are designed, such as long distance travel, navigating congested urban traffic, cruising, sport and racing, or off-road conditions.Motorcycles are one of the most...
throttle, clutch and (now rarely) brake cables - control surfaces on small aircraftAircraftAn aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
- remote hi-hatHi-hatA hi-hat, or hihat, is a type of cymbal and stand used as a typical part of a drum kit by percussionists in R&B, hip-hop, disco, jazz, rock and roll, house, reggae and other forms of contemporary popular music.- Operation :...
s in drum kitDrum kitA drum kit is a collection of drums, cymbals and often other percussion instruments, such as cowbells, wood blocks, triangles, chimes, or tambourines, arranged for convenient playing by a single person ....
s - operate terminal device hook on prosthetic arms
- Lawn mowerLawn mowerA lawn mower is a machine that uses a revolving blade or blades to cut a lawn at an even length.Lawn mowers employing a blade that rotates about a vertical axis are known as rotary mowers, while those employing a blade assembly that rotates about a horizontal axis are known as cylinder or reel...
throttle and dead man's switchDead man's switchA dead man's switch is a switch that is automatically operated in case the human operator becomes incapacitated, such as through death or loss of consciousness.... - interlocking in electrical switchgearTransfer switchA transfer switch is an electrical switch that reconnects electric power source from its primary source to a standby source. Switches may be manually or automatically operated...
- trigger activation for remotely located machine guns on French 1930's era Char B1 bis tanks, and for the DISA tripod used with the Madsen machine gunMadsen machine gunThe Madsen was a light machine gun developed by Julius A. Rasmussen and Theodor Schoubue and proposed for adoption by Captain Vilhelm Herman Oluf Madsen, the Danish Minister of War and adopted by the Danish Army in 1902...
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