30 a return spring 100 is inserted around the screw 19 in this manner the position of the control lever 20 is adjusted by acting on the nut 30 in order to be able to regulate the type of braking desired the control lever 20 has a groove 21 able to accommodate the cable 22 fig1 to be connected to the lever not shown of a brake on the handlebar the end of the cable 22 is blocked in the cavity 21 by means of a bolt 101 again in the outer body 16 of the caliper a through hole is provided wherein a sheath fastening pin or revolving pin 23 engages the pin 23 is blocked at the bottom by an open snap ring 24 fig4 so as to be able to turn freely inside the through hole the pin 23 has a through hole 25 through which the cable 22 is inserted and at one end of the pin 23 the sheath 55 that covers the cable 22 is blocked the spring 100 around the screw 19 is preferably covered by a dust guard 31 of rubber or synthetic material a hollow body 13 having a substantially upturned t shaped section that is having a cylindrical tang with a disc shaped base is positioned inside the outer caliper body 16 in the base of the hollow body two opposing seats 33 are created only one visible able to accommodate a pair of rollers 34 integral in position with respect to the caliper body 16 the seats 33 communicate with a pair of opposed cams 35 only one visible with an opposite incline when the brake lever on the handlebar is actuated pulling of the cable 22 causes shifting of the lever 20 that actuates the screw 19 that.