Background Art: Torque-and consequently the power with which the chain drives the drive wheel of a bicycle-depends on the power with which the cyclist pushes the pedal and on the length of pedal, that is the moment arm-r (N = F * r).

If it were possible to extend the length of the pedal without limitation, we could, without changing the cyclist's force when pushing the pedal, achieve greater torque and greater drive power on the chain, and thus increase the speed of the bicycle.

However, the problem is that the pedal cannot be extended indefinitely because we are limited by the length of the cyclist's legs. The length of the crank arm is approximately 20 cm; therefore the difference between the highest and the lowest point reached by the pedal during rotation is approximately 40 cm.

Disclosure of Invention : Extension of the pedal (moment arm-r) while simultaneously maintaining the difference between the highest and the lowest point reached by the pedal during rotation can be achieved by a folding, two-part pedal (two-fold pedal) and a slightly altered construction of the entire bicycle, with its seat moved slightly forward in relation to the bicycle's construction.

Brief Description of Drawings The invention will be illustrated by the following figures showing: Fig. 1,2 and 3: component parts and the construction of the two-fold pedal ; Fig. 4: modification of the two-fold pedal, which is necessary on the side of the bicycle with the drive chain sprocket-wheel ; Fig. 5: behaviour of a two-fold pedal during stroke-how the two-fold pedal folds and unfolds ; Fig. 6: change of construction of the entire bicycle.

Best Mode for Carrying Out the Invention : The goal-extension of the pedal (the moment arm-r) while simultaneously maintaining the difference between the highest and the lowest point reached by the pedal during rotation-can be reached by developing a folding, two-part pedal and modifying the construction of the entire bicycle. a) modification of the pedal (two-fold pedal) : The pedal consists of two parts instead of just one-on top of the familiar"lower pedal"E, an additional"upper pedal"F is flexibly attached on its top. The two properly positioned"pedal sprocket-wheels"G and A and the"pedal chain"J ensure that the upper pedal always remains in horizontal position during rotation. Thus, the two-fold pedal is extended when necessary while the difference between the highest and the lowest point reached by the pedal during rotation is maintained.

Pedal sprocket-wheel A is positioned between the lower pedal and the"bicycle's entire frame"B. Sprocket-wheel A is fixed on the bicycle frame B-during the pedal's rotation, sprocket-wheel A remains fixed. Pedal sprocket-wheel G is fixed on the upper pedal F through the"upper pedal axis"I. Therefore, sprocket-wheel G, axis I and upper pedal F are fixed, welded together. Upper pedal axis I runs through lower pedal E. The joint described between lower pedal E and upper pedal F is movable. For this joint, the well-known technology of movable joints can be used, as widely applied in the construction of cranks (ball bearings). Sprocket-wheels A and G have the same diameter.

Sprocket-wheels A and G fitted in the way described are connected by chain J.

Sprocket-wheel A is fixed (on the bicycle frame B). During the stroke of the two-fold pedal sprocket-wheel G moves around sprocket-wheel A; sprocket-wheel G must rotate because it is fixed onto the immobile sprocket-wheel A and chain J. During the stroke, the entire pedal rotates counter-clockwise while sprocket-wheel G rotates clockwise. Upper pedal F is fixed to the clockwise-rotating sprocket-wheel G. The position of the upper pedal F is defined by the two converse motion directions.

Because sprocket-wheels G and A are the same diameter, it is possible for upper pedal F to always be in a horizontal position during pedaling.

When lower pedal E is in the horizontal rising position, the two-fold pedal is completely folded. When lower pedal E is in the horizontal falling position, the two- fold pedal is completely unfolded. In other words: when the two-fold pedal reaches its outermost point after its rotation axis K, it is completely folded. After this point it commences unfolding again and it is completely unfolded when it reaches its outermost point before its rotation axis K.

The diameter of sprocket-wheels A and G can range from a few centimetres to as much as approximately 20 centimetres, when-if the length of lower pedal E is 20 cm-they are already in contact (and no longer need chain J for connection). The length of chain J depends on the size of sprocket-wheels A and G and the length of lower pedal E. Chain J must not be loosely fitted on sprocket-wheels A and G; on the contrary, it must always encircle half of sprocket-wheel A and half of sprocket- wheel G, without regard to the position of the two-fold pedal at any given time.

On the side where"drive sprocket-wheel"C is located, the sprocket-wheel A is located between drive sprocket-wheel C and lower pedal E. Here, sprocket-wheel A is fixed to bicycle frame B as well (and not on the drive sprocket-wheel). This fixed fastening has multiple technical solutions. The most simple is through a special extension of frame M. The extension of frame M is fixed onto bicycle frame B on its upper part, while on the other side sprocket-wheel A is fastened on it. b) modification of bicycle frame: Because of the position of upper pedal F, the part of pedal H, where the cyclist exerts pressure on the pedal, shifts forward, which is why the axis K of the two-fold pedal must shift backwards and seat L must shift forward. The length of these shifts depends on the length of upper pedal F, which can, in principle, be extended at will.

If the upper pedal is longer, the length of the entire bicycle frame B must be extended-the rear wheel is moved backwards together with rotation axis K of the two-fold pedal in relation to the entire construction of the bicycle.

Industrial Applicability : The invention can be used not only in the manufacture of bicycles but also in the production of and improvements to all drive mechanisms intended for travelling and shifting loads through the use of the power of human legs (ultralight aeroplanes, smaller boats, lifts).