Abstract: An inertia mechanism for gymnastic bicycles having a pedalling axle, the mechanism includes an inertia flywheel and a set of cogged crowns of different diameters and different number of cogs mounted on the flywheel and operatively connected to each other and to the pedalling axle so that weight and the size reduction of the flywheel are counterbalanced by the set of the cogged crowns actuated upon the actuation of the pedalling axle.

Abstract: A gymnastic bicycle includes a device for regulating the physical effort necessary for tilting handlebars with respect to a chassis during exercises simulating rowing, together with a vibrator formed by a lever having one end permanently connected to the articulation of the handlebar tube with respect to the chassis. The other end of the lever has a roller capable of contacting a polygonal surface which rotates as a result of pedalling. The polygonal surface forms part of or is closely linked to an inertia flywheel which constitutes a power accumulator and pedalling regulator. Contact or separated positions of the roller with respect to the polygonal surface are obtained by a control knob fixed to a shaft provided at its free end with two axially spaced surfaces which, on rotation of the knob and shaft, alternately contact a plate, thereby pivoting the lever with respect to the chassis of the bicycle.

Abstract: A gymnastic bicycle includes a frame mountable on the floor and having at a forward portion a tubular part or stem which supports a handlebar and at a rear portion a tubular part supporting a seat and provided with a pedal shaft operable by pedals. Incorporated in an articulation zone between the lower end of the tubular piece or stem supporting the handlebar and the frame of the bicycle is a friction device having an adjustable resistance which permits the physical force of the user to be adjusted when he practices an exercise corresponding to rowing, such exercise taking place by the forward and backward oscillation of the handlebar. At such articulation zone is a main vibrating mechanism whose main operating element is a polygonal member securely mounted on the pedal shaft so that the vibrations produced as a result of the operation of the main vibrating mechanism are transmitted to the handlebar of the bicycle.