Gates bike belt drive systemBelt-driveBelt-drive single-speed rear hub on a Trek DistrictBelt-drive crankset on a Trek DistrictBelt-drive multi-speed rear hub gear on a Trek Soho
A belt-driven bicycle is a chainlessbicycle that uses a flexible belt, typically a synchronous toothed design, in order to transmit power from the pedals to the wheel.
The application of belt drives to bicycles is growing, especially in the commuter bicycle market, due to the low maintenance and lubrication-free benefits. Belt drives are also available for stationary and fitness bicycles.[1]
Some belt systems are lighter than conventional chain-driven system.[5][6]
Drawbacks
Derailleurs cannot be used, so a hub gear is used if multiple gear ratios are required.
Most belts cannot be taken apart as a chain can, so a frame must be able to accommodate the belt by having an opening in the rear triangle or an elevated chain stay. There is only one option where the belt can be spliced and joined through the rear triangle.[7]
Belts come in limited selection of lengths, which must be accommodated in the design of the frame.
Belt-driven bicycles and their repair or replacement parts are scarcer at shops than bicycles with conventional chain.
Front and rear pulleys or sprockets must be well aligned to avoid excessive friction and wear. A chain is more flexible in this respect.[8]
Compared to a chain, belts are typically run at a much higher tension. This is done in order to avoid skipping of the belt while in use. However, high belt tensions can reduce the life expectancy of the bearings in the bottom bracket, as well as in the rear hub.[citation needed]
First-generation pulleys with dual guides had problems with snow becoming compacted and trapped in the pulley (up to complete inoperability in some cases). Second generation (one guide, wheel side) and third generation (center guide) improve upon the design.[citation needed]
Tensioning
Tensioning can be implemented in all the same ways that single-speed chain drives can be tensioned. The fork ends for the rear axle are horizontal, in line with the belt, with or without chain tugs, which allows the distance between the rear wheel axle and the crank axle to be adjusted. The fork ends themselves can be moved, to change the distance between the rear wheel axle and the crank spindle. The fork ends are fixed but there is a separate tensioner pulley, which changes the travel distance of the belt.
Bicycle tensioners.
Tensioner pully. (behind bar at middle right edge)
Eccentric bottom bracket.
Horizontal fork ends.
History
A belt drive for a bicycle was patented in the United States on April 8, 1890 by Charles D. Rice, Patent # 425,390.[9]
Mathew J. Steffens
In 1898, Mathew Joseph Steffens of Chicago, Illinois received a patent for a rear-wheel drive electric bicycle using a driving belt attached to the periphery of the pneumatic-tired wheel. By the early 1900s, some motorcycles were using leather drive belts.
Bridgestone Picnica
The Bridgestone Picnica belt-drive bicycle was introduced in the early 1980s. It used a tooth-belt drive like auto timing belts and Harley-Davidson drive belts, along with a novel two-part chainring that increased belt tension with increasing load. The Picnica was a folding bicycle, and part of the appeal of the belt drive was cleanliness. The Picnica was a small-wheel bicycle, so belt tension may have been less than on a bicycle with standard-size wheels. It was apparently successful, but was offered mainly in Japan.
Bridgestone offered belt-drive bicycles in the USA until they left the market about 1994. Since their innovation, they have continuously offered belt-drive bicycles in Japan including their best-selling Albelt model.
In 1984 and 1985, Mark Sanders, a designer who had earned his degree in mechanical engineering from Imperial College, London, designed a folding bicycle as part of his graduate studies in an Industrial Design Engineering (IDE) program. The program was run jointly by Imperial College and the Royal College of Art in London. He collaborated with a design engineer from Gates Corporation to outfit his bicycle with a belt, rather than a chain.
When his project was complete, Sanders chose entrepreneur and former Greg Norman manager James Marshall and a Glasgow manufacturer to turn his award-winning design into a product. The manufacturer coined the name Strida, and in 1987 the bicycle began rolling off the production line. In 2002 production was moved to Taiwanese manufacturer Ming Cycle in order to meet increased demand, and as of 2007, Ming Cycle fully owned the Strida brand and intellectual property rights.
iXi bicycles, distributed in the United States by Delta Cycle Corporation, followed in 2004 with a compact design that, like Strida, featured a belt drive. Other folding-bike manufacturers that have implemented a belt drive include U.S. company Bike Friday and Netherlands-based Bernds.
In 2007, Gates Corporation developed a high-modulus 8mm synchronous belt and sprocket system called the Carbon Drive System. The belt's pitch allowed for lower tension requirements to help prevent skipping. Lightweight, patent-pending sprockets have mud ports, openings under each tooth, which work to slough off debris.
In 2009, an increasing number of bicycle companies, including Trek and f8 Cycles, offered belt-driven bicycles. While builders initially focused on single-speeds and internal hubs, in early 2009 f8 used a Gates-compatible fixed-gear cog designed by Phil Wood & Co.,[10] offering a belt-driven fixed-gear bicycle.
In 2009, Wayne Lumpkin, owner of Spot Brand and best known as the founder of Avid, designed a belt system called CenterTrack. In 2010, Gates Corporation acquired a patent from Lumpkin for CenterTrack,[11] a new belt-and-pulley design that improves on the initial Carbon Drive System design. CenterTrack is more tolerant to misalignment than its predecessors. It is also lighter, 20% stronger due to a wider 11mm belt, yet has narrower pulleys, making packaging with the latest generation of internally geared hubs much easier.[3][12] The company’s CDX belt is the first belt drive designed for severe off-road use on mountain bikes.
In 2010, Daimler introduced the Smart eBike, a power-electric hybrid bicycle featuring Gates Carbon drive-belt system. The eBike is designed for a clean, grease-free ride.[13] Other notable eBike brands include Grace and Pi-Mobility.
In 2012, Continental AG’s subsidiary ContiTech introduced the CONTI® DRIVE SYSTEM for bicycles.[14] The CDS belt drive shared the basic operation of the early 8mm Gates Carbon Drive system, but employed aramid instead of carbon fibers in its construction. The Conti CDS was designed exclusively for ‘normal use on properly laid’ roads and paths.[15] ContiTech eventually switched to carbon belts for bicycle use, citing issues with traction using aramid fibers.[16]
The CDS belt drive was utilized on some Trek bicycles and the Sladda utility cycle marketed by IKEA of Sweden. After reports of failures of the belt itself and a recall, CDS was withdrawn from the belt-drive bicycle market.[17][18]
In 2018, Veer Cycles created the first belt drive conversion kit that allows riders to convert their chain driven bikes to belt drives. The belt is spliced to fit through the rear triangle and eliminates the need for a frame with a split already in it.[19][7] Veer has also shown a concept where the rear cog can change size (and thus gearing),[20] a concept that is reminiscent of derailleurs and implies that a hub gear with planetary gears may not be necessary in order to implement multi-speed gears on a belt-driven bike.
The possibilities for belt-driven bicycles are increasing as manufacturers of internal hub gears (gears inside the rear hub, which allow riders of belt-driven bicycles to shift easily) introduce new designs such as the Shimano Alfine 11 and Fallbrook Technologies's NuVinci. Other major internally geared hub makers include SRAM, Sturmey-Archer, Rohloff and Kindernay.
Another option to provide gears is to create a gearbox bicycle using a bracket-mounted gearbox like the Pinion P.18.[21]
The belts are typically made by the same manufacturing companies that produce toothed belts for automobiles, machinery, and other synchronous belt-drive applications.[citation needed]
Belt-drive manufacturers
Current and former manufacturers of belt-drive bicycles and pedal belt-drive systems include:
Trek Bicycle Company— District, Soho and Zektor bicycle models. Also under the Villager brand.
Gallery
Trek TAB Belt Drive front sprocket rear view
Trek TAB Belt Drive rear sprocket front view
Trek TAB Belt Drive rear sprocket rear view
Trek TAB Belt Drive rear sprocket side view with 3-speed hub. The connection point between chainstay and seatstay necessary to insert belt drive is visible.
Yet another way to tension the belt by positioning the fork end
Horizontal fork ends and tugs for providing belt tension
Horizontal fork ends and tugs for providing belt tension (without the wheel, for clarity)
A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered or motor-assisted, pedal-driven, single-track vehicle, with two wheels attached to a frame, one behind the other. A bicycle rider is called a cyclist, or bicyclist.
A bicycle wheel is a wheel, most commonly a wire wheel, designed for a bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels.
A derailleur is a variable-ratio bicycle gearing system consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another.
A hub gear, internal-gear hub, internally geared hub or just gear hub is a gear ratio changing system commonly used on bicycles that is implemented with planetary or epicyclic gears. The gears and lubricants are sealed within the shell of the hub gear, in contrast with derailleur gears where the gears and mechanism are exposed to the elements. Changing the gear ratio was traditionally accomplished by a shift lever connected to the hub with a Bowden cable, and twist-grip style shifters have become common.
A 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.
A track bicycle or track bike is a bicycle optimized for racing at a velodrome or outdoor track. Unlike road bicycles, the track bike is a fixed-gear bicycle; thus, it has only a single gear ratio and has neither a freewheel nor brakes. Tires are narrow and inflated to high pressure to reduce rolling resistance.
A sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a chain, rack or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which radial projections engage a chain passing over it. It is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth except for timing pulleys used with toothed belts.
A single-speed bicycle is a type of bicycle with a single gear ratio. These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle.
A fixed-gear bicycle is a bicycle that has a drivetrain with no freewheel mechanism such that the pedals always will spin together with the rear wheel. The freewheel was developed early in the history of bicycle design but the fixed-gear bicycle remained the standard track racing design. More recently the "fixie" has become a popular alternative among mainly urban cyclists, offering the advantage of simplicity compared with the standard multi-geared bicycle.
Chain drive is a way of transmitting mechanical power from one place to another. It is often used to convey power to the wheels of a vehicle, particularly bicycles and motorcycles. It is also used in a wide variety of machines besides vehicles.
A 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 in the 1880s, but were mostly supplanted by chain-driven bicycles due to the gear ranges possible with sprockets and derailleurs. Around the 2000s, due to advancements in internal gear technology, a small number of modern shaft-driven bicycles have been introduced.
Bicycle gearing is the aspect of a bicycle drivetrain that determines the relation between the cadence, the rate at which the rider pedals, and the rate at which the drive wheel turns.
Strida is a portable belt-driven folding bicycle with a distinctive A-shaped collapsible frame, designed by British engineer and designer Mark Sanders. The first model, Strida 1, was released in 1987 and the latest, Strida 5.2, in 2009.
Motorcycle components and systems for a motorcycle are engineered, manufactured, and assembled in order to produce motorcycle models with the desired performance, aesthetics, and cost. The key components of modern motorcycles are presented below.
Bicycle 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.
A string-driven bicycle or stringbike is a bicycle that uses an external chainless rope and pulley drive system instead of a traditional bicycle chain and sprockets. The mechanism was commercialized by Hungarian Stringbike Kft which presented models in 2010 with a 19-speed system with no duplicate gears and having a 350% gear range.
A 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 special nut is threaded on, and the lever is closed to tighten the cam and secure the wheel to the fork. Wheels equipped with quick release mechanisms can be removed from the bicycle frame and replaced without using tools by opening and closing the cam lever, thus more quickly than wheels with solid axles and nuts. On the negative side, a quick-release hub renders a wheel more vulnerable to theft and care must be taken to ensure that the mechanism is properly tightened.
Veer Cycle is an American manufacturer of drive belts for bicycles and light electric vehicles. The company introduced Split Belt as their first product in 2018, which is a belt that can be spliced with rivets, and therefore can be installed on bicycle frames with ordinary rear triangles. Veer claims their split belt is as strong as a chain, but with a higher efficiency. The belts are made of nitrile reinforced with carbon fibre, and can be used on vertical droputs or full suspension bikes by using a belt tensioner.
↑ "Daimler Begins Deliveries of smart Electric Bikes". EV World. 2012. Archived from the original on 29 July 2012. Retrieved 10 May 2012. The drive is also of a very high quality with a completely maintenance- and oil-free carbon toothed belt instead of a conventional bicycle chain.
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Tensioner pully. (behind bar at middle right edge)
Eccentric bottom bracket.
Horizontal fork ends.
