Background Art Present solutions of folding bicycles do not pay much attention to the folding of pedals or pedal cranks.

The U. S. patent Nr. 4,634,138 desribes a method of folding a bicycle having small diameter wheels by sliding in a part of the handlebars, the seat and the wheels, and tipping the pedals towards the pedal crank. The solution is very dangerous because of a possibility of injure, and its production is rather demanding. There is a danger that, as a consequence of a small failure, the pedal will tip during cycling under full load with possible serious consequences for the cyclist.

The pedal tipping is similarly solved in the U. S. patent Nr. 4,598,923. The patent solves the folding of a bicycle to a size of a suitcase with a diameter of very small wheels. Reduction in the width of a folded bicycle is contemplated by folding the pedals to the cranks, but no method for the solution of this problem is described in detail.

The most often appearing are the solutions which solve the pedal and pedal cranks folding by dismounting the pedals as well as by dismantling the pedal cranks.

The solution for folding bicycles which is described in the US patent Nr. 5,205,573 consists in dismounting the pedals, pedal cranks, wheels and even the tyres, and putting them into a case. This cannot be regarded as folding a bicycle, but as overall dismantling the bicycle.

Also according to the solution which is described in the patent DE 4446112 Al pedals, cranks and the whole central part of the bicycle are dismounted.

Folding pedals in the solutions for folding bicycles known so far has not been possible, because the pedals together with the pedal cranks have been rigidly fixed in the central assembly of the bicycle. Therefore, their folding was impossible, but in the course of the bicycle folding it was necessary to dismantle the pedals together with the cranks.

This problem is solved in the present innovation by solving the clamping of the pedals with the pedals cranks in the central assembly of a bicycle, thus allowing their folding towards the bicycle centre.

Disclosure of Invention The above problem is solved by a universal central assembly of a bicycle consisting of pedals with pedal cranks, a quick-clamping screw, a bearing, a cylindrical journal and a shaft, the nature of which consists in that the journals of the pedal cranks inserted in the shaft hollow are equipped with a quick-clamping screw connecting the left journal with the right journal of the pedal cranks slidingly and together with the shaft rotationally. The journals of the pedal cranks may be coupled with the hollow shaft by a spring.

The advantage of this solution consists in the fact that after releasing the quick-clamping screw the pedal cranks can be slided out, thus allowing to insert them into the space of the bicycle frame. Folding the pedal cranks makes it possible to reduce the overall width of the folded bicycle to one third of the original width. A further, no less important advantage is the fact that the risk of injury is minimised. A possibility of a cyclist injury is much smaller than with the current solutions of tipping pedals, because in the case of releasing the journals of pedal cranks no tipping of pedals can occur. A release of the journals of pedal cranks can be immediately sensed by the cyclist without possibly falling down. The solution is universal for all bicycle types, those from bicycles for children to bicycles for adults, from mountain bikes to road bicycles.

A considerable advantage of the construction of the central assembly is the fact that folding the bicycle does not require any tools, it is not time demanding and it does require neither any special skill nor any expert knowledge.

A survey of the figures in the drawing The solution of the central assembly of a bicycle is explained in more detail in the enclosed Figure which shows a horizontal section through the central assembly of the bicycle and the central structure of the bicycle.

Examples of Embodiments The universal central assembly consisting of pedals with pedal cranks, a quick- clamping screw, a hollow cylindrical journal and a shaft, as shown in Fig. 1, is characterised in that the journals 1, 1\'of the pedal cranks inserted in the hollow of the shaft 2 with a spring, are equipped with a quick-clamping screw 3. The quick- clamping screw 3 couples the journals 1, 1\'of pedals in such a way that these can be slided out of the hollow of the shaft 2 and slided into the hollow of the shaft 2.

When folding the bicycle, after releasing the quick-clamping screw 3 the journals 1, 1\'of the pedal cranks are released and slided out of the hollow shaft 2. By turning the journals 1, 1\'of pedals with pedal cranks these are inserted into the space of the bicycle frame. When unfolding the bicycle, the journals 1, 1\'of pedal cranks are slided into the hollow of the shaft 2 and clamped with the quick-clamping screw.

Industrial Applicability A universal central assembly of a bicycle according to the present invention can be utilised in the production of bicycles, especially of folding bicycles.