In the year 1991 at the Budapest Technical University at the Faculty of Traffic Engineering there were about 20 young engineers, who took part at a postgraduate course to become doctors of philosophy. Dr. Gábor Rácz, leading professor of the team raised several problems concerning bicycles, including the functional limitations concerning the changing of gears, the problems connected with using the chain and the associated gears, and provoked the students to try to come up with non-conventional solutions.

Two of the group, Robert Kohlheb and Oliver Vonhauser took the challenge seriously and suggested a mechanism using no chain. Here respective freewheels were arranged at both sides of the rear wheel, and respective wires were wound around the outer cylindrical surface of the freewheels that could be pulled by the mechanism to cause rotation of the wheel. The mechanism was clumsy, using several rods that assisted the conversion of the circular movement of the pedals into swinging movement of respective swinging arms adapted to pull the wires. A young outsider, a bike fan, Attila Kaboldy assisted the small team with wild ideas. After a while, serious optimisation took place, and a second model was built, in which the pedals had cranked arms, and in the swinging arm an elongated guiding path was made for guiding a ball bearing placed at the junction of the two cranked arm portion. The rotation of the pedal caused the swinging arms to swing around respective auxiliary shafts.

At this phase, Mr. Kaboldy gave up co-operation and let the team work alone, and Mr. Michael Lantos, patent attorney who got acquainted with the project during his work, recognised the genuine character of the idea and the need of the three inventors for financial and organisational assistance. He joined in the three in the project and from this time onwards a systematic development started.

There were several problems to solve:

• an easy and efficient way of causing the swinging arms to alternating swinging movement;

• a simple and efficient way to move the height of the pulling point along the two oppositely swinging arms simultaneously;

• a way of providing overlapping characteristics in the two swinging movements so that one arm moves always forward, thus the rider cannot notice the changing of the pulling operation from one side to the other;

• a simple method for forcing the swinging arms to return, that should keep the string biased as well.

It was a long optimisation job to solve all these problems, and the inventors used state of the art computer technology to simulate relative movements, speeds and loads on all elements. In the course of several years altogether six models were made, each differed from the previous one in one or more detail, and the new string-bike took shape. Starting in 1996 the bike was exhibited in several inventors' exhibitions, including Brussels, Geneva, Nürnberg and Budapest, and it obtained several gold and silver medals. The last version was awarded a gold medal at the First Inventors' Olympic Games in Budapest. The reaction of the public was very positive, and according to those who tried riding the bike, the ride was fantastic, a real good sensation coupled with an ease in handling.

The group was optimistic, the patent examinations terminated in the major countries (EP and US) with allowance, however, business success was still behind. A Hungarian manufacturer, Mr. István Szívós, fell in love with the design, and used his engineering workshop to build a prototype. This bike was exhibited in Friedrichshafen, at the Eurobike exhibition, and there was again a high interest on behalf of the press and of the public. Every other visitor got enthusiastic about the design, and those who had the chance of riding it, reported their positive experiences. The profession was conservative, they looked at the bike, often smiled, but did not want to realise that at the end of the XXth century someone may dare building a bike without chain.

The inventors are still optimistic, because the perfect design of the string-bike will eventually break through, and the superior properties will convince the public and the profession that there is a place under the sun for this new design. A co-operation partner or a potential licensee would provide great help in bringing the project to production and to major markets.