string bike, chainless

price now, over 3400 us$


The joy of cycling without chain

With STRINGBIKE® you will experience an unparalleled easy and smooth riding. This is because of its revolutionary new symmetric driving system: the STRINGDRIVE® where pure rolling motion provides high efficiency that remains the same in all gears and stays just as efficient even after long periods of service.



The creation of symmetry, the ancient natural property of all living creatures has been the main driving force behind developing the STRINGBIKE®. The asymmetry caused by the placement of the chain and the gears at one side of the frame, has been the source of lots of problems which have remained unnoticeable until all bikes were driven basically in the same asymmetric way.



STRINGBIKE® is so surprisingly novel and different from all existing bikes that one has to re-evaluate all con­ventional features of classic bikes.


One can get used to this new driving sensation and system after a few minutes of test ride and can immediately enjoy the superb comfort of cycling. The correct change of gears needs some training; it cannot be forced to sudden great jumps but has to be moved as fast as it lets itself be moved. In no load condition the movement can be faster.

STRINGBIKE

Last but not least the STRINGBIKE® is a beautiful piece of art, and the reciprocating movement of the swinging members with the never ceasing winding up and down of the ropes from their associated drums provide a nice visual impression.


Change of gears

In each swinging period the forward movement of the swinging member pulls the driving rope forward by means of the rope wheels. The common shaft of the rope wheels is pivotally guided along a traction path tooled in the rear arm. The actual distance between the centre of rotation and the shaft changes as the shaft is traveling up and down along this traction path. When the shaft takes the outermost position, the rope wheels take the greatest distance, and when the shaft is moved closer to the centre of rotation, the displacement decreases. The traction path has 19 neighboring recesses, and each of them corresponds to a respective gear position.



With the turning the single shifting knob on the right handle grip of the bike forward or backward, these travelling shafts are forced to move (in fact roll) up or down along the traction path. When the bike is idle i.e. it is stationary or momentarily rolling and it is not driven by force, the pivoted shafts at both driving units can move easily up or down, thus we can change the gears even if the driver is not rotating the pedals or the bike is stationary.With the turning the single shifting knob on the right handle grip of the bike forward or backward, these travelling shafts are forced to move (in fact roll) up or down along the traction path. When the bike is idle i.e. it is stationary or momentarily rolling and it is not driven by force, the pivoted shafts at both driving units can move easily up or down, thus we can change the gears even if the driver is not rotating the pedals or the bike is stationary.



During active driving, one of the left or right driving units pulls the rope forward, and the pulling force presses the traveling shaft to the actual recess of the traction path, and under such circumstance the shaft cannot move. On the other side, however, the other swinging member is free to be moved, thus the pulling force of the shifting wire can move it by one step up or down. When the pedals are further turned forward, this previously idle side will take up the load and by now the previous side will be free, and the force of the shifting wire moves this shaft to the same position what the other side has taken previously. In shifting under load, the shifting knob must be kept biased when the driver is rotating the pedals, and the position of the shafts in both sides will gradually change in the desired direction, i.e. the gears will be changed just as the driver desires it. Any position is stored and kept when the shifting knob is not turned any more.



This is a totally different mechanism for shifting gears than used at any other customary drive, and it provides a continuous change of gears at any time, however, the shifting knob needs not be forced, but kept being pushed slightly in the desired direction. As long as the bias is maintained, the gears are changed in a step-by-step manner. The shifting is faster under no load condition, but even under load, the shift is easy and continuous.



The total shift range is 3.5 : 1.



The driver must get used to be tolerant with changing the gears, it occurs faster when he turns the pedals faster, and slower if the driving is slow.



The change of gears will slightly drive the bike forward, therefore shifting when the bike is moving or rolling in a non-driven (idle) way is easy. If the bike is stationary, the shift can be made either by slowly rolling the bike forward, or by slightly turning the pedals backward, or by raising temporarily the rear wheel from the ground.

Future objectives

1. Different types of bikes

Currently the STRINGBIKE® has been realized in three models of trekking bike. Parallel with expected (increasing) interest on the side of consumers, almost all other types can be designed, as the STRINGDRIVE® drive train meets the needs of almost all types of bikes.

By changing the diameter of the rope drums on the rear hub, the 2.5 shift range can be fitted shifted to higher (1.7-4.2) or lower (1.2-3) gear range.

2. Racing bikes

Theoretically, the STRINGDRIVE® ideally fits as drivetrain for racing bikes of any type. It is within the close objectives of the designers of STRINGBIKE® to satisfy that need.

3. Special bikes

The longer chain a bike uses, the better can it be replaced by the rope of STRINGDRIVE®. This is especially true for recumbent bikes and three-wheel bikes like rickshaws. At his latter types the property that gears can be changed at any time including shifting under load, constitutes a very essential advantage.

4. Further features

With STRINGDRIVE® there exists the possibility to use different transmission ratios at the left and right hand sides of the bike. This is because the two identical driving units need not have to have the same positioning. This might mean that those who have some problems with one of their legs, can adjust the load on either side separately. The offset positioning of the gears between the two sides can provide a yet never experienced new possibility, and it might open up the way to biking for those being temporarily not so fit to use both of their legs with full load.

5. Changing the driving curve

The designers think to have provided the optimum driving curve. This might not be so for everyone, or drivers might wish to temporarily change the driving characteristic e.g. to refresh new groups of muscles with changing the driving curve. It is an objective of the designers to meet such demands.





http://www.stringbike.com/

Stringbike From Wikipedia,

The Stringbike is a bicycle that uses a wire rope and pulley drive system instead of a traditional bicycle chain and sprockets.[1][2][3][4] It uses two steel wire ropes attached to pulleys attached to swinging lever and cam mechanisms, one on each side of the bike. These mechanisms replace the round sprockets found on chain-driven bikes. Unlike some traditional 10-speed gears using a derailleur, there is no slippage when changing gear ratios.[5] The Stringbike uses a 19 gear ratio system with no duplicates and a total gear range of 3.5 to 1. The transmission ratio can be changed with a shifting knob located on the right-side handle grip. Gear ratios can be changed even when the bicycle is stationary.[6]

Hungarian designers from the manufacturing company Schwinn Csepel Zrt, unveiled the bicycle in 2010 in Padova, Italy.[7]


http://en.wikipedia.org/wiki/Stringbike

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Stringbike: Adiós a la cadena en las bicicletas
Por: Lisandro Pardo @ lunes, 20 de septiembre de 2010

La bicicleta ha estado entre nosotros por más de doscientos años, y aunque los modelos actuales pueden parecer muy similares entre sí, siempre hay lugar para la innovación. Así ha quedado demostrado con algunos prototipos de bicicletas sin cadena, pero la Stringbike de origen húngaro bien podría convertirse en una opción comercial viable. ¿Cómo es que funciona? En vez de la clásica cadena, la Stringbike recurre a cables de acero, eliminando factores como la grasa y la dificultad a la hora de quitar la rueda trasera.


Conozco una cosa o dos sobre bicicletas, pero admito que estoy muy por debajo del nivel de un aficionado. Algunas reparaciones son preferibles que las haga un profesional (después de todo, alguien va a subirse a la bicicleta), mientras que elementos como el freno a contrapedal son un verdadero misterio para mí. Sin embargo, cualquiera puede notar que las bicicletas han ido cambiando con el paso de los años, tal vez no de forma radical, pero sí perceptible. Algunos conceptos se han ido perpetuando con los modelos, por lo que una bicicleta sin cadena puede parecer algo en verdad extraño. Sin embargo, ya se han visto algunos intentos flotando en la Web, los cuales podrían ser perfectamente viables como opción comercial. El modelo conocido como Stringbike es uno de ellos.

La Stringbike reemplaza la típica cadena con cables de acero conectados a poleas, y unos discos especialmente diseñados para la transferencia de fuerza. Los discos reemplazan a los típicos platos en otras bicicletas, y pueden ser intercambiados según la necesidad del usuario. El concepto de cambios también ha sido simplificado, ya que es posible obtener una marcha diferente con sólo variar la altura de las poleas. Otro detalle interesante es que un usuario puede instalar los cables de forma asimétrica. Por supuesto, la forma más eficiente de transferencia es utilizando ambas piernas de la misma forma, pero alguien lesionado puede transferir parte de la carga de una pierna a otra, y seguir utilizando la bicicleta.

Como si eso fuera poco, las ruedas de la bicicleta pueden ser fácilmente quitadas para ahorrar espacio y facilitar el transporte en un vehículo. Muchos usuarios arrojan maldiciones al aire cada vez que deben lidiar con una cadena repleta de grasa y una caja de cambios que complica aún más las cosas, pero tal y como muestra el vídeo superior, quitar la rueda trasera en la Stringbike es algo muy sencillo. No estamos seguros de cuándo podría estar disponible al público, pero si los costos de producción y el precio final se mantienen en un nivel razonable, no debería pasar mucho tiempo. Personalmente creo que preferiría a una bicicleta un poco más ortodoxa, aunque todo se reduce al nivel de conveniencia. Si es más barata y más fácil de mantener, bienvenida sea.

http://www.neoteo.com/stringbike-adios-a-la-cadena-en-las-bicicletas.neo