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. [1] [2] [3] [4] 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.
The mechanism has a rocker arm [5] [6] on each side of the bike that replaces the round sprockets (which are usually only on the right side) on chain driven bikes. In contrast to traditional derailleur chain drives, the drive does not slip when changing gears, [7] and the gearing can be changed even when the bicycle is almost stationary. [8] (similarly to a hub gear), but also "at full throttle." [6] Two Dyneema ropes (ultra-high-molecular-weight polyethylene, UHMWPE) attached to pulleys attached to swinging lever and cam mechanisms have been used, one on each side of the bike.
In the 1990s, string-driven bicycles were developed by Mihály Lantos and others. [6]
In the 2010s, the concept was commercialized by Hungarian Schwinn Csepel Zrt. and Stringbike Kft. Patents were filed by Stringdrive Technologies Kft for Robert Kohlheb and Mihaly Lantos in 2010 alternating drive elements for bikes (8602433 and 20110266768), and in 2011 on flexible pulley-drives for bikes (9162525). [9]
In 2010, the world's first commercial string-driven bicycle was presented in Padova, Italy by the manufacturing company Stringbike Kft. [10] The company has produced and sold stringbikes with aluminium frames and carbon frames under the brand Stringbike.
In 2012 it was announced that the Hungarian rider Ferenc Szőnyi would use the model Stringbike E line RAAM with a carbon frame in Race Across America, [11] [12] where he placed 14th overall. [13]
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 sprocket, sprocket-wheel or chainwheel is a profiled wheel with teeth that mesh with a chain, track 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.
A drive shaft, driveshaft, driving shaft, tailshaft, propeller shaft, or Cardan shaft is a component for transmitting mechanical power and torque and rotation, usually used to connect other components of a drivetrain that cannot be connected directly because of distance or the need to allow for relative movement between them.
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 chainless bicycle is a bicycle that transmits power to the driven wheel through a mechanism other than a metal chain.
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.
On a bicycle, the cassette or cluster is the set of multiple sprockets that attaches to the hub on the rear wheel. A cogset works with a rear derailleur to provide multiple gear ratios to the rider. Cassettes come in two varieties, freewheels or cassettes, of which cassettes are a newer development. Although cassettes and freewheels perform the same function and look almost the same when installed, they have important mechanical differences and are not interchangeable.
A toothed belt; timing belt; cogged belt; cog belt; or synchronous belt is a flexible belt with teeth moulded onto its inner surface. Toothed belts are usually designed to run over matching toothed pulleys or sprockets. Toothed belts are used in a wide array of mechanical devices where high power transmission is desired.
Sterling Bicycle Co. was a 19th-century American bicycle company first based in Chicago, Illinois before relocating to Kenosha, Wisconsin.
The Rohloff Speedhub is an epicyclic internal hub gear for bicycles, developed and patented by Rohloff AG. It has been manufactured and marketed by that company since 1998. The Speedhub 500/14 has 14 equally spaced, sequential, non-overlapping gear ratios operated by a single twistgrip. The overall gear range is 526%, meaning the highest gear is 5.26 times as high as the lowest gear. Individual gear shifts when shifting up give an increase of about 13.6%.
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.
A belt-driven bicycle is a chainless bicycle that uses a flexible belt, typically a synchronous toothed design, in order to transmit power from the pedals to the wheel.
Lucien Charles Hippolyte Juy was a French industrialist who made derailleur gears. He is credited with making the first derailleur with a collapsible parallelogram. A hinged frame swung in and out from the frame and fed the chain to one of a number of sprockets attached to the hub. Juy's derailleurs, sold as Simplex derailleurs, were novel in having a jockey wheel to correct the tension of the chain as it moved across differently sized sprockets.
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.
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