A string-driven bicycle or stringbike is a

bicycle A bicycle, also called a pedal cycle, bike, push-bike or cycle, is a human-powered transport, human-powered or motorized bicycle, motor-assisted, bicycle pedal, pedal-driven, single-track vehicle, with two bicycle wheel, wheels attached to a ...

that uses an external chainless rope and

pulley Sheave without a rope A pulley is a wheel on an axle or shaft enabling a taut cable or belt passing over the wheel to move and change direction, or transfer power between itself and a shaft. A pulley may have a groove or grooves between flan ...

drive system instead of a traditional

bicycle chain A bicycle chain is a roller chain that transfers power (physics), power from the Bicycle pedal, pedals to the Drive wheel, drive-Bicycle wheel, wheel of a bicycle, thus propelling it. Most bicycle chains are made from carbon steel, plain carbo ...

and

sprocket A sprocket, sprocket-wheel or chainwheel is a profiled wheel A wheel is a rotating component (typically circular in shape) that is intended to turn on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the whe ...

s. 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.

Design

The mechanism has a rocker arm on each side of the bike that replaces the round

s (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, and the gearing can be changed even when the bicycle is almost stationary. (similarly to a

hub gear 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 h ...

), but also "at full throttle." Two

Dyneema Ultra-high-molecular-weight polyethylene (UHMWPE, UHMW) is a subset of the thermoplastic polyethylene. Also known as high-modulus polyethylene (HMPE), it has extremely long chains, with a molecular mass typically between 2 and 6 million amu. The l ...

ropes (ultra-high-molecular-weight polyethylene, UHMWPE) attached to pulleys attached to swinging lever and

cam Cam or CAM may refer to: Science and technology * Cam (mechanism), a mechanical linkage which translates motion * Camshaft, a shaft with a cam * Camera or webcam, a device that records images or video In computing * Computer-aided manufacturin ...

mechanisms have been used, one on each side of the bike.

History

In the 1990s, string-driven bicycles were developed by Mihály Lantos and others. 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). In 2010, the world's first commercial string-driven bicycle was presented in

Padova Padua ( ) is a city and ''comune'' (municipality) in Veneto, northern Italy, and the capital of the province of Padua. The city lies on the banks of the river Bacchiglione, west of Venice and southeast of Vicenza, and has a population of ...

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

by the manufacturing company Stringbike Kft. 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 The Race Across America, or RAAM, is an ultra-distance road cycling race held across the United States that started in 1982 as the Great American Bike Race. RAAM is one of the longest annual endurance events in the world. All entrants must prov ...

, where he placed 14th overall.

References

External links

Website (archived)
Cycle types {{cycling-stub