As is known, the optimum length of a bicycle pedal crank, as measured from the pedal axis to that of the central driving assembly pivot pin, will depend on the physical characteristics of the cyclist, the bicycle type and the running path features. Actually, as the pedal crank length is increased, the lever arm will be in turn increased and accordingly the required force will decrease, with a corresponding decreasing of the maximum number of revolutions which can be obtained.

The professional use bicycles, or high quality bikes, are conventionally provided with pedal crank seals made of special materials, allowing to provide a suitable stiffness with a comparatively small weight. The mentioned seals, which are very expensive, must be replaced for any different required lengths of the pedal crank.

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide, by a single pedal crank, different equivalent lengths, so as to fit the pedal

crank to cyclists having different physical characteristics (even with the lower limbs of asymmetrical configuration), as well as to fit it to racing or mountain bikes of different size or to the running path type.

For achieving the above mentioned object, as well as yet other objects, which will become more apparent hereinafter, the subject pedal crank comprises a recess for engaging therein a cam or the like element, in which a threaded attachment is formed for the pedal pivot pin, which, upon assembling, will lock the cam insert in the seat or recess therefor. By turning through 180 degrees said cam insert, or replacing it by other different eccentricity cam inserts, it will be possible to easily change the equivalent length of the pedal crank.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be disclosed in a more detailed manner hereinafter with reference to the accompanying drawings, which illustrate, by way of a not limitative example, a possible embodiment thereof and in which: Figure 1 is a side view of the pedal crank according to the invention; Figure 2 is a side view illustrating the cam or eccentric insert; Figure 3 is a top plan view, as partially cross-sectioned, of the subject pedal crank, the cam insert and pedal pivot pin being shown in an assembling position; and

Figure 4 illustrates an enlarged detail of the pedal crank end portion, as partially cross- sectioned, with the cam insert and pedal pivot pin being shown in an assembling position thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT The reference number 1 of the above mentioned figures shows the pedal crank rod, whereas the reference number 2 shows a hole for assembling the pedal crank on a pivot pin of a central driving assembly. At the other end portion of the pedal crank a recess 3 having a shape corresponding to that of the cam insert 4 is provided.

More specifically, said cam insert is provided with a threaded hole 5 arranged at an eccentric position and being provided with an abutment 6, which, upon assembling, will be located on a corresponding abutment 7 of the recess 3.

The reference number 8 shows the pedal pivot pin, the threaded end portion 9 of which is threaded in the hole 5 of the eccentric or cam insert 4, which will be accordingly locked in its recess or seat 3.

Between the treaded attachment 9 of said pivot pin 8 and the pedal crank, it is possible to engage, in a suitable engagement seat 10, a washer 11 having a configuration corresponding to that of the recess 3.

By turning through 180° the cam insert 4 to bring the threaded hole 5 to a position opposite to that shown in the figures, it is possible to obtain a different equivalent length of the pedal crank. By assembling cam insert of different eccentricity, it will be accordingly possible to provide other

different equivalent lengths.

The cam insert could also be engaged at the central driving assembly pivot pin or on both ends of the pedal crank, in order to allow the equivalent length thereof to be adjusted in a broader range. Said cam insert, moreover, could be locked in its seat by using locking screws, or any other suitable known means.

The pedal crank, in particular, can be made starting from Ergal carbon fibers, titanium or other suitable materials. The subject pedal crank is very advantageous since it can be easily made while allowing a cyclist to buy at a comparatively small cost, a plurality of different eccentricity cam inserts, to choose therefrom the length best fitted to the bicycle running path.

Thus, it should be apparent that the main object of the present invention has been fully achieved.

While the invention has been disclosed with reference to a preferred embodiment thereof, it should be apparent that the disclosed embodiment is susceptible to several modifications and variations, all of which will come within the scope of the appended claims.