Actuation device of the control cable of a bicycle gearshift, comprising: - a casing , configured for fixing to bicycle handlebars, - a cable-winding bush mounted in the casing angularly rotatable about a rotation axis (X) in a first angular direction (A) between a first angular position and a last angular position and in a second angular direction (B) between the last angular position and the first angular position, - a rotary member mounted in the casing in a rotary manner about the rotation axis (X) and a stationary member mounted in a non-rotary manner in the casing , wherein one from the rotary member and the stationary member is provided with at least one first pointer engaged on a fastening track formed on the other member, - the fastening track comprising at least one first plurality of stop positions engageable in sequence by said pointer , the cable-winding bush passing from one angular position to an adjacent angular position after the passage of the pointer from one stop position to an adjacent stop position, - each stop position being angularly spaced from an adjacent stop position by a respective indexing angle (C), each indexing angle (C) corresponding to a rotation of the cable-winding bush by an amount equal to the indexing angle (C), characterised in that said fastening track extends along a closed loop path and in that a first stop position that determines the first angular position of the cable-winding bush is angularly spaced from the next stop position by an indexing angle (C) equal to the indexing angle (C) necessary to make the cable-winding bush rotate from the penultimate angular position to the last angular position. - a casing , configured for fixing to bicycle handlebars, - a cable-winding bush mounted in the casing angularly rotatable about a rotation axis (X) in a first angular direction (A) between a first angular position and a last angular position and in a second angular direction (B) between the last angular position and the first angular position, - a rotary member mounted in the casing in a rotary manner about the rotation axis (X) and a stationary member mounted in a non-rotary manner in the casing , wherein one from the rotary member and the stationary member is provided with at least one first pointer engaged on a fastening track formed on the other member, - the fastening track comprising at least one first plurality of stop positions engageable in sequence by said pointer , the cable-winding bush passing from one angular position to an adjacent angular position after the passage of the pointer from one stop position to an adjacent stop position, - each stop position being angularly spaced from an adjacent stop position by a respective indexing angle (C), each indexing angle (C) corresponding to a rotation of the cable-winding bush by an amount equal to the indexing angle (C), characterised in that said fastening track extends along a closed loop path and in that a first stop position that determines the first angular position of the cable-winding bush is angularly spaced from the next stop position by an indexing angle (C) equal to the indexing angle (C) necessary to make the cable-winding bush rotate from the penultimate angular position to the last angular position. <EOS>