Hub gear
Encyclopedia
Bicycle gearing
A 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,...
changing system commonly used on bicycle
Bicycle
A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....
s that is implemented with planetary or epicyclic
Epicyclic gearing
Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer gears, or planet gears, revolving about a central, or sun gear. Typically, the planet gears are mounted on a movable arm or carrier which itself may rotate relative to the sun gear...
gears. The gears and lubricants are sealed within the hub-shell of the bicycle's rear wheel, as opposed to derailleur gears, where the gears and mechanism are exposed to the elements. Changing the gear ratio was traditionally accomplished by a shift lever
Shifter (bicycle part)
A bicycle shifter or gear control or gear levers is a component used to control the gearing mechanisms and select the desired gear ratio. Typically, they operate either a derailleur mechanism or an internal hub gear mechanism. In either case, the control is operated by moving a cable that connects...
connected to the hub with a Bowden cable
Bowden cable
A Bowden cable is a type of flexible cable used to transmit mechanical force or energy by the movement of an inner cable relative to a hollow outer cable housing...
, and twist-grip style shifters have become common.
Hub gear systems generally have a long and largely maintenance-free life though some are not suitable for high-stress use in competitions or hilly, off-road conditions. Many commuter or urban cycles such as European city bike
European city bike
A European city bike, or simply city bike is a bicycle designed for frequent short, moderately paced rides through relatively flat urban areas...
s are now commonly fitted with 7-speed gear-hubs and 8-speed systems are becoming increasingly available. Older or less costly utility bicycle
Utility bicycle
A utility bicycle is a bicycle designed for practical transportation, as opposed to bicycles which are primarily designed for recreation and competition, such as touring bicycles, racing bicycles, sport/training bicycles, and mountain bicycles. The vast majority of bicycles can be found in the...
s often use 3-speed gear-hubs, such as in bicycle sharing systems. Many folding bicycles use 3-speed gear-hubs. Modern developments with up to 14 gear ratios are available.
History
Before epicyclic gears were used in bicycle hubs, they were used on tricycles. Patents for epicyclic hubs date from the mid-1880s. The first patent for a compact epicyclic hub gear was granted in 1895 to the American machinist Seward Thomas Johnson of Noblesville, Indiana, U.S.A. This was a 2-speed but was not commercially successful.In 1896 William Reilly of Salford, England patented a 2-speed hub which went into production in 1898 as 'The Hub'. It was a great success, remaining in production for a decade. It rapidly established the practicality of compact epicyclic hub gears.
By 1902 Reilly had designed a 3-speed hub gear. He parted company with the manufacturer of 'The Hub' but had signed away to them the intellectual rights to his future gear designs. To circumvent this problem, the patents for Reilly's 3-speed were obtained in the name of his colleague, James Archer. Meanwhile, well-known English journalist and inventor Henry Sturmey had also invented a 3-speed hub. In 1903 Frank Bowden, head of the Raleigh cycle company, formed The Three-Speed Gear Syndicate, having obtained the rights to both the Reilly/Archer and Sturmey 3-speeds. Reilly's hub went into production as the first Sturmey Archer 3-speed.
In 1902 Mikael Pedersen
Mikael Pedersen
Mikael Pedersen was a Danish inventor much associated with the English town of Dursley. He is chiefly known today for the highly distinctive Pedersen bicycle...
(who also produced the Dursley Pedersen bicycle
Pedersen bicycle
The Pedersen bicycle, also called the Dursley Pedersen bicycle is a bicycle that was developed by Danish inventor Mikael Pedersen and produced in the English town of Dursley. Though never hugely popular, they enjoy a devoted following and are still produced today...
) patented a 3-speed hub gear and this was produced in 1903. This was said to be based on the "counter shaft" principle but was arguably an unusual epicyclic gear, in which a second sun was used in place of an ring gear. In 1904 the Fichtel & Sachs company (Germany, Schweinfurt
Schweinfurt
Schweinfurt is a city in the Lower Franconia region of Bavaria in Germany on the right bank of the canalized Main, which is here spanned by several bridges, 27 km northeast of Würzburg.- History :...
) produced a hub gear under license to Wanderer
Wanderer (car)
Wanderer was a German manufacturer of bicycles, motorcycles, automobiles, vans and other machinery. Established as Winklhofer & Jaenicke in 1896, the company used the Wanderer brand name from 1911, making civilian automobiles until 1941 and military vehicles until 1945.-History:Winklhofer &...
, and by 1909 there were 14 different 3-speed hub gears on the British market.
By the 1930s hub gears were used on bicycles all over the world. They were particularly popular in the UK, The Netherlands, the German speaking countries and Scandinavia. Since the 1970s, they have become much less common in the English-speaking countries. But in many parts of northern Europe, where bicycles are regularly used as daily transport rather than merely for sport or leisure, hub gears are still widely used. The cheaper and stronger (but less reliable) derailleur system now started to appear and offer a wider gear range.
By 1987 Sturmey-Archer made only 3- and 5-speed hubs, and Fichtel & Sachs and Shimano made only 2- and 3-speed hubs. In that year the first book (apart from service manuals) for some 80 years dealing solely with epicyclic bicycle gears was published. Since then there has been a slow but steady increase in interest in hub gears, reflected in the wider range of products now available.
In 1995 Sachs introduced the Elan
Sachs Elan
The Sachs Elan was an epicyclic internal hub gear for bicycles, developed and manufactured by the bicycle division of the German company Fichtel & Sachs. It was considered heavy and production units were plagued with quality issues. The gear hub was discontinued before the turn of the...
, the first hub gear with more than 12 speeds, and an overall range of 339%. Three years later Rohloff came out with the Speedhub 500/14
Rohloff Speedhub
The Rohloff Speedhub is an epicyclic internal hub gear for bicycles, developed and patented by Rohloff AG. It has been manufactured and marketed by the German company since 1998. The Speedhub 500/14 has 14 equally-spaced sequential gears with no overlapping ratios and is operated by a single...
, a gear hub with 14 speeds and a range of 526%, comparable to that of a 27 speed derailleur gear system, and also sufficiently robust and light weight for mountain biking
Mountain biking
Mountain biking is a sport which consists of riding bicycles off-road, often over rough terrain, using specially adapted mountain bikes. Mountain bikes share similarities with other bikes, but incorporate features designed to enhance durability and performance in rough terrain.Mountain biking can...
. In 2007 NuVinci started manufacturing stepless ∞-speed (CVT) hubs for commuter bicycles, with a range of about 350%.
As of 2008, Sturmey-Archer makes 3-, 5- and 8-speed hubs, SRAM (successor to Fichtel & Sachs) make 3-, 5-, 7- and 9-speeds and Shimano make 3-, 7- and 8-speeds. In February 2010 Shimano announced the introduction of the Shimano Alfine 700, an 11-speed model.
Though most hub gear systems use one rear sprocket, SRAM
SRAM (bicycles)
SRAM Corporation is a privately held bicycle component manufacturer based in Chicago, Illinois, founded in 1987. SRAM is an acronym comprising the names of its founders, Scott, Ray, and Sam, .In 2008, the company received a strategic investment from Trilantic Capital Partners, formerly known as...
's Dual Drive system combines an epicyclic hub with a multi-speed rear derailleur system to provide a wide-ranging drivetrain concentrated at the rear wheel. In 2010 Canyon
Canyon Bicycles
Canyon Bicycles GmbH is a German manufacturer of racing bikes, mountain bikes and triathlon bikes based in Koblenz, Germany.-Company history :...
introduced the 1442, a hybrid hub which uses a similar epicyclical/derailleur combination.
Brompton Bicycle
Brompton Bicycle
Brompton Bicycle is a manufacturer of folding bicycles based in Brentford, London.The Brompton folding bicycle and accessories are the company's core product, noted for its self-supporting compact size when stored. All available models of the folding bicycle are based on the same hinged bicycle...
have their own design, with a two-speed derailleur coupled to a special three-speed wide-ratio Sturmey-Archer hub, the "BWR" (Brompton Wide Ratio). The system is useful for folding bicycles (where a multiple front chainset could foul the bike's folding mechanism) and in recumbent bicycle
Recumbent bicycle
A recumbent bicycle is a bicycle that places the rider in a laid-back reclining position. Most recumbent riders choose this type of design for ergonomic reasons; the rider's weight is distributed comfortably over a larger area, supported by back and buttocks...
s and freight bicycle
Freight bicycle
Freight bicycles, carrier cycles, freight tricycles, cargo bikes, or bakfietsen, are human powered vehicles designed and constructed specifically for transporting large loads. Vehicle designs include a cargo area consisting of a steel tube carrier, an open or enclosed box, a flat platform, or a...
s (where small wheels and/or increased weight require a wider range of gears with smaller steps). Hub gears have in the past also been used on motorcycle
Motorcycle
A 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...
s, although this is now rare.
Principle of operation
The simplest 3-speed hubs use a single planetary epicyclic gearset. The sun gear (in yellow above) is mounted solidly to the axle and is thus fixed. In low gear, the sprocket drives the ring gear, also called the annulus, (in red above), while the planet carrier (in green above) drives the hub, giving a gear reduction. In mid gear, the ring gear is connected to both the sprocket and hub, giving a direct drive. The planets (in blue) cycle freely. In high gear, the sprocket is switched to drive the planet carrier, while the ring gear remains connected to the hub, giving an overdrive gear.The hub axle of a hub gear (unlike that of a derailleur system) will carry torque in all gears except direct drive, and so must be securely braced against rotation. While anti-rotation washers between the dropout and axle nut have often proved adequate, wider-ranging modern systems use a reaction arm affixed to the chain stay. Rear wheels with drum brakes (a feature on some commuter bicycles) require a reaction arm anyway.
Most hub gears are operated in a similar manner, with a single twist, trigger or thumb-shifter. An exception is the older style of Sturmey-Archer 5-speed, which used a second shift cable to change between close and wide-range sun gears, effectively giving two 3-speed hubs in one unit. The middle gear in both ranges was direct drive, so there were five distinct gears. They could either be controlled with a special 5-speed shifter which operated both cables, or with a regular 3-speed shifter and a friction shifter.
Advantages
- Hub gears are sealed within the hub, which protects them from water, grit, and impacts. Thus hub gears usually require less maintenance and can be more reliable over time than comparable external derailleur gear systems, which may require more adjustments and replacement of parts (front chainrings, rear sprockets, narrow derailleur-chain).
- Hub gears completely avoid the danger of collision with the spokes and wheel-collapse that derailleur systems can suffer.
- Hub gears can change gear ratios when the rear wheel is stationary. This can be useful for commuter cycling with frequent stops and for mountain bikingMountain bikingMountain biking is a sport which consists of riding bicycles off-road, often over rough terrain, using specially adapted mountain bikes. Mountain bikes share similarities with other bikes, but incorporate features designed to enhance durability and performance in rough terrain.Mountain biking can...
in rough terrain. - Hub gears can be simpler to use for inexperienced riders, because there is generally only a single shifter to operate and there are no overlapping gear ratios. By contrast, modern derailleur systems often have two shifters, and require some forethought to avoid problematic gear combinations.
- Hub gears provide a means for shifting gear ratios on drivetrains incompatible with external deraileurs such as belt drivesBelt-driven bicycleA belt-driven bicycle is a chainless bicycle that uses a toothed synchronous belt to transmit power from the pedals to the wheel. The belts are typically made by the same manufacturing companies that produce timing belts for automobiles, machineries, and other synchronous belt drive...
and shaft drivesShaft-driven bicycleA shaft-driven bicycle is a bicycle that uses a drive shaft instead of a chain to transmit power from the pedals to the wheel. Shaft drives were introduced over a century ago, but were mostly supplanted by chain-driven bicycles due to the gear ranges possible with sprockets and derailleurs...
. - The single chainlineChainlineChainline is the angle of a bicycle chain relative to the centerline of the bike's frame. A bicycle is said to have perfect chainline if the chain is parallel to the frame, which means that the rear sprocket is directly behind the front sprocket...
allows for a full chain enclosure chain guard, so the chain can be protected from water and grit and clothing can be protected from contact with the lubricated chain. - The single chainline does not require the chainBicycle chainA bicycle chain is a roller chain that transfers power from the pedals to the drive-wheel of a bicycle, thus propelling it. Most bicycle chains are made from plain carbon or alloy steel, but some are nickel-plated to prevent rust, or simply for aesthetics. Nickel also confers a measure of...
to bend or twist. As a result, the chain can be constructed differently, with parallel pins instead of barrel-shaped ones. Line-contact between the bearing surfaces, instead the point-contact of a derailleur chain, greatly extends the working life of all components. - On bicycles with fixed chain-lines, no chain tensioner is required, eliminating a part that could otherwise become damaged in rough terrain- an advantage for off-road cyclists. Where a tensioner is required, a short cage is usually sufficient to take up the chain slack.
- The single external sprocket means that the wheel can be built with no or much less dish, making it stronger than a similar wheel dished to accommodate multiple sprockets. The hub shell of gear hubs is also often of a larger diameter than that of derailleur hubs, meaning the spokes on such wheels may be shorter, making the wheel stronger, and allowing for the use of fewer of spokes.
Disadvantages
- Hub gears are typically more expensive than derailleur systems.
- At commuter/recreational power levels, current gear-hubs are typically about 2% less efficient than reasonably maintained derailleur gears.
- Gear-hubs will tend to be heavier than equivalent derailleur systems, and the additional weight is concentrated at the back wheel. On rear-suspension bicycles in sporting use this unsprung weightUnsprung weightIn a ground vehicle with a suspension, the unsprung weight is the mass of the suspension, wheels or tracks , and other components directly connected to them, rather than supported by the suspension...
will adversely affect traction and braking. - Gear-hubs are more complex and, aside from the simpler 3-speeds, may be difficult for the ordinary rider to repair - most certainly not as a side-of-the-road procedure. However, failures generally give plenty of warning and repair may be an option.
- Gear-hubs systems are generally incompatible with quick releaseQuick release skewerA quick release skewer is a mechanism for attaching a wheel to a bicycle. It consists of a rod threaded on one end and with a lever operated cam assembly on the other. The rod is inserted into the hollow axle of the wheel, a nut is threaded on, and the lever is closed to tighten the cam and secure...
mechanisms/skewer axles. - The gear-hub is an integral part of the wheel and it is not possible to change the wheel without also changing the gear mechanisms.
Hub gears in everyday use
- Traditional hub gears are indexed at the shifter making operation dependent on correct cable tension (and lubrication thereof). In practice, gear-jumping and consequent internal damage are unusual except in high-mileage units. Modern hub gear-units incorporate the indexing in the unit itself and are therefore unaffected by shifting malfunctions caused in this way.
- The Sturmey Archer and Fichtel & SachsZF SachsZF Sachs AG is a German manufacturer of automotive parts, producing powertrain and suspension components. It was formerly known as Fichtel & Sachs, Mannesmann Sachs and Sachs...
'Torpedo' systems defaulted to top gear at slack-cable, which could make the bicycle usable for long distance travel in flat terrain even if a fault developed in the change mechanism (rather like a derailleur system, which can be manually set to a high gear in case of a similar fault). Some modern hub gear systems (e.g. 7-speed Shimano) default to bottom gear and are thus more dependent on the (generally) very reliable cable-pull.
Hybrid gearing with derailleurs
Some systems combine internally-geared hubs with external derailleurs. A freewheeling hub with a sprocket suitable for narrow chain can be combined with a double or triple crankset and front derailleur, in order to provide a wider range and closer gear ratio spacing. A chain tensioner or a rear derailleur is needed to take up chain slack, and care is needed not to over-torque the hub by using too small a chainring/sprocket ratio.Alternatively, some hubs can accept two dished drive sprockets, between which the rider can switch with a rear derailleur. Careful sprocket selection can allow the available gear ratios when using one sprocket to fall half-way between those available when using the second sprocket, providing half-step gearing, as on the Brompton
Brompton Bicycle
Brompton Bicycle is a manufacturer of folding bicycles based in Brentford, London.The Brompton folding bicycle and accessories are the company's core product, noted for its self-supporting compact size when stored. All available models of the folding bicycle are based on the same hinged bicycle...
6-speed folding bicycle. This concept is used and extended in the SRAM Dual Drive system, where a conventional multi-speed cassette is mounted to a 3-speed hub. A similar version of the ever-popular AW hub is manufactured by Sturmey Archer. This system may be useful on bicycles which cannot accept a front derailleur. The German company Canyon
Canyon Bicycles
Canyon Bicycles GmbH is a German manufacturer of racing bikes, mountain bikes and triathlon bikes based in Koblenz, Germany.-Company history :...
introduced the 1442 in 2010, a hybrid hub which uses a similar epicyclical/derailleur combination.
When both front and rear derailleurs are used with a geared hub, the result is a very wide-ranging drivetrain, at the expense of increased weight and complexity.
Advanced hub gears
Advanced hub gears offer a higher numbers of gears by using multiple epicyclic gears driven by each other. Their ratios are chosen to give more evenly spaced gears and a larger total gear range. The operating principle of such units is the same as with less advanced systems, with a trigger or twist shifter with sequential shifting.- The 12-speed Sachs ElanSachs ElanThe Sachs Elan was an epicyclic internal hub gear for bicycles, developed and manufactured by the bicycle division of the German company Fichtel & Sachs. It was considered heavy and production units were plagued with quality issues. The gear hub was discontinued before the turn of the...
was the first hub gear with 10 or more speeds in the market (1995-1999). Unfortunately, it was considered heavy and plagued with quality issues, hence discontinued after a few years.
- The 14-speed Rohloff SpeedhubRohloff SpeedhubThe Rohloff Speedhub is an epicyclic internal hub gear for bicycles, developed and patented by Rohloff AG. It has been manufactured and marketed by the German company since 1998. The Speedhub 500/14 has 14 equally-spaced sequential gears with no overlapping ratios and is operated by a single...
hub gear, introduced in 1998, has a range exceeding 5 to 1, and are now more comparable to 24-speed or 27-speed derailleur systems, since the latter have three overlapping ranges often with only about 14 distinct gears. As there is no overlap, the hub gear is easier to operate, and an oil bath creates a comparable mechanical efficiency to derailleur gears.
- The 11-speed Shimano Alfine 700 hub gear, introduced in 2010, has a gear range exceeding 4 to 1, comparable to 20-speed derailleur drive-trains, and internals running in an oil bath, for greater mechanical efficiency.
List of multispeed hub gears
- This list is of multispeed hub gears with 7 speeds or more. It may be incomplete.
| Brand | Product | Introduced | Discontinued | Speeds | Gear width | Weight | purpose |
|---|---|---|---|---|---|---|---|
| Rohloff AG Rohloff AG Rohloff AG is a German company from Fuldatal near Kassel that manufactures hub gears, bicycle chains and tools that are known for their durability and high performance... |
Speedhub 500/14 Rohloff Speedhub The Rohloff Speedhub is an epicyclic internal hub gear for bicycles, developed and patented by Rohloff AG. It has been manufactured and marketed by the German company since 1998. The Speedhub 500/14 has 14 equally-spaced sequential gears with no overlapping ratios and is operated by a single... |
1998 | 14 | 526% | 1700 g (non disc) 1825 g (disc) |
Sport, Touring | |
| 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... |
Alfine SG-700 Shimano Alfine The Shimano Alfine series of products is a comfort and urban oriented product series first seen by the market around 2005. It includes internally geared hubs, hydraulic disc brakes and levers, chain tensioners, dynamo hubs, cranksets, shift levers, and complete wheels... |
2010 | 11 | 419% | 1600 g (claimed) 1744 g |
City, Sport | |
| 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... |
Alfine SG-500 Shimano Alfine The Shimano Alfine series of products is a comfort and urban oriented product series first seen by the market around 2005. It includes internally geared hubs, hydraulic disc brakes and levers, chain tensioners, dynamo hubs, cranksets, shift levers, and complete wheels... |
2006 | 8 | 307% | 1600 g | City | |
| 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... |
Shimano Nexus Inter-8 | 8 | 307% | 1550-1990 g | City | ||
| 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... |
Shimano Nexus Inter-7 | 1995 | 7 | 244% | 1465-1860 g | City | |
| Sachs/SRAM Corporation | Sachs Elan Sachs Elan The Sachs Elan was an epicyclic internal hub gear for bicycles, developed and manufactured by the bicycle division of the German company Fichtel & Sachs. It was considered heavy and production units were plagued with quality issues. The gear hub was discontinued before the turn of the... |
1995 | 1999 | 12 | 339% | 3500-4000 g | City |
| SRAM Corporation | SRAM i-Motion 9 | 2005 | 9 | 340% | 2000-2400 g | City | |
| SRAM Corporation | SRAM Spectro S7 | 2010 | 7 | 303% | 1645-1826 g | City | |
| Sturmey Archer | XRF-8 | 2007 | 8 | 305% | 1480-1600 g | City | |
See also
- Bicycle drivetrain systemsBicycle drivetrain systemsBicycle drivetrain systems are used to transmit power on bicycles, tricycles, quadracycles, unicycles, or other human-powered vehicles from the riders to the drive wheels. Most also include some type of a mechanism to convert speed and torque via gear ratios....
- Bicycle gearingBicycle 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,...
- Gear inchesGear inchesGear inches is a system that assigns numerical measurements to bicycle gear ratios, to indicate how low or high a gear is.Gear inches has no current physical significance; it corresponds to the diameter in inches of the main wheel of an old-fashioned penny-farthing bicycle with equivalent gearing...
- NuVinci
- ShifterShifter (bicycle part)A bicycle shifter or gear control or gear levers is a component used to control the gearing mechanisms and select the desired gear ratio. Typically, they operate either a derailleur mechanism or an internal hub gear mechanism. In either case, the control is operated by moving a cable that connects...
Manufacturers
- BendixBendix CorporationThe Bendix Corporation was an American manufacturing and engineering company which during various times in its 60 year existence made brake systems, aeronautical hydraulics, avionics, aircraft and automobile fuel control systems, radios, televisions and computers, and which licensed its name for...
- From 1950s to 1970s, produced the two-speed "Kickback" hub - Fichtel & Sachs
- RohloffRohloff SpeedhubThe Rohloff Speedhub is an epicyclic internal hub gear for bicycles, developed and patented by Rohloff AG. It has been manufactured and marketed by the German company since 1998. The Speedhub 500/14 has 14 equally-spaced sequential gears with no overlapping ratios and is operated by a single...
- Schlumpf
- ShimanoShimanoShimano, 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...
- SRAMSRAM (bicycles)SRAM Corporation is a privately held bicycle component manufacturer based in Chicago, Illinois, founded in 1987. SRAM is an acronym comprising the names of its founders, Scott, Ray, and Sam, .In 2008, the company received a strategic investment from Trilantic Capital Partners, formerly known as...
- Sturmey-ArcherSturmey-ArcherSturmey-Archer is a manufacturing company originally from Nottingham, England. It primarily produces bicycle hub gears but has also produced motorcycle hubs....
External links
- Flash Animation of Hub Gear
- Overview of gear ratios and ranges for existing internal gear hubs by Sheldon BrownSheldon Brown (bicycle mechanic)Sheldon Brown was an American bicycle mechanic and technical authority on bicycles. He contributed to numerous print and online sources related to bicycling, bicycle mechanics and maintenance, including his own website — and received numerous awards for his contributions.-Biography:Brown...
- Tony Hadland's Bicycle Gear History and Technical pages