A continuously variable transmission including an input shaft; a flywheel connected to the input shaft; a drive pulley connected to the input shaft and defined by a first and a second half-pulley defining a groove of variable width for a belt; and a centrifugal actuating assembly having a centrifugal actuating device, which activates above a first threshold value of the angular speed of the input shaft to connect the drive pulley to the flywheel by a clutch interposed between the first half-pulley and the flywheel, and a speed regulating device, which is active above a second threshold value of the angular speed of the input shaft to adjust the width of the groove of the drive pulley, and therefore the work diameter of the belt.