Bicycle devices are already known able to increase, during rotation, the active lever of the pedal so as to exalt its efficiency and therefore the speed of the athlete.

Moreover, the application of such devices seems to be conditioned by the minimal space for their housing, along the hub of the frame and the pedal.

It is the aim of the present invention to allow a perfect working of a device for improving the efficiency of the push on the pedal by means of the new structure of the rear fork of the frame, comprising two arms linked, respectively, to the hub carrying the pedals, and to a housing, inside which said device may comfortably rotate.

The advantage of the present invention appears to be evident.

The present invention will be described hereinbelow relating to the enclosed drawings in which e preferred embodiment is shown.

Figures 1 and 2 show an axonometric view and a plane view of a device for improving the efficiency of the push on the pedal, as applied to a frame T of a competition bicycle B.

Figures 3 and 4 show an exploded axonometric view and a plane square section of the components'shape.

Figures 5,6, 7 and 8 show the different positions obtained by the pedals during the rest, push and the reascent of the pedals P.

Figure 9 shows a plane scheme of the insertion and fastening phase of the device according to the present invention inside its housing provided on said frame T.

Figure 10 shows in a plane scheme the condition of perfect parallelism, requested for preventing from breaking or mechanic blocks of the system, taken by the motion axis AC of the chain with respect to the longitudinal axis AT of the frame, after the application of the device to said frame.

The enclosed figures show a bicycle frame provided with a rear fork FP whose arms are respectively linked to the hub of the

frame and to a housing for receiving and allowing the rotation of a device for improving the efficiency of the push on the pedal of competition bicycles and similar, consisting of : - a round housing 1, protected by a bottom FO for blocking the inlet of foreign bodies that might be harmful for the working of the mechanisms contained therein, applied to said frame T in a position eccentric to said hub M, and for containing a bearing 2, kept into position by a blocking metal ring 3 inserted in a special groove 4 internal to the housing's structure; - a flange 5 fixed to said bearing 2 by means of a blocking metal ring 6 inserted into a special groove 7 on the external structure of the flange, provided with projections 8 so as to allow the coupling thereof, by means of threaded pins 9, with crown wheels 10,11 ; - crown wheels 10,11 for transferring the motion to the wheels of the bicycle B, coaxial to said bearing 2 and provided with passing-through holes 12,13 for allowing the connection thereof with a special gear 14; - a gear 14, coaxial to said crown wheels 10, 11, assured to the same by means of said threaded pins 9 and linked through the same to said flange 5 applied to said bearing 2 contained in said housing 1, engaged onto special cylindrical elements 15 placed along the external edge of the right pedalier 16 ; - a right pedalier 16, coaxial with pins PN of said hub M on said frame T, carrying a pedal P and provided with a special

perimetrical structure 17 for containing special cylindrical elements 15, forming the mechanical equivalent to a roller chain, for determining the rotation of the gear 14 engaged therewith and of the components linked thereto; - a left pedalier 18 of a standard kind, coaxial with the pins PN of the hub M of the frame T, carrying a pedal P.

As far as the description of the working is concerned, the push on the pedals P determines the rotation of the pedaliers 16 and 18 onto pins P of hub M of bicycle B and the consequent rotation of gear 14 carrying the crown wheels 10,11, engaged onto cylindrical elements 15 placed on the outer shape of the right pedalier 16, onto a bearing 2 contained inside housing 1 provided on frame T, through the flange 5 onto which it is fixed, together with said crown wheels, by means of threaded pins 9.

The different rotation centres of pedaliers 16,18 and of the crown wheels 10,11 determine an increase of the moment transmitted to the wheels of said bicycle B, due to the increase of the power arm with respect to the axis of the crowns during the push phase on the pedals, and to the reduction of the resistant moment during the reascent phase of the same, determined by the reducton of the value of said arm with respect to said axis.

As an example, according to the different diameters of the pedalier 16 and of the gear 14 connected thereto, making use of

pedaliers of 17 cm length and conferring to the elements an eccentricity of 2 cm, the crown wheels 10, 11 acquire a gain of 20% in movement.

Furthermore, the device determines the perfect parallelism between the movement axis AC of the chain and the longitudinal axis AT of the frame, allowing to operate the change gear mechanism for moving the chain on the respective crowns 10, 11, maintaining the same as much as possible in axis with the rear crowns CP of the driving wheel of the means, thus avoiding that an excessive tension causes the breaking of said chain or that a too low tension determines the unhooking of the same from crowns 10,11 or from the rear crown CP.