Column-wheel for a chronograph, chronograph and chronograph watch including such a wheel

A column-wheel for a chronograph including:

• a ratchet provided with a plurality of teeth the shape of which defines the direction of rotation of the column-wheel;
• and
• a superstructure coaxial to the wheel and having n≧3 order rotational symmetry, the peripheral part of the superstructure forming n columns parallel to the wheel axis and arranged substantially along the periphery of the ratchet, each column including an outer part, the cross-section of which is substantially shaped like a truncated triangle with a base substantially parallel to the circumference of the wheel and a front side, called the leading edge, and a back side, called the trailing edge, extending from the base towards the interior of the wheel;
• wherein said cross-section is asymmetrical, a first angle α between the leading edge and the base being smaller than a second angle β between the base and the trailing edge;
• and wherein the superstructure includes a hub connected to the columns by arms so as to reinforce said columns, the height of the hub and the arms being comprised between 10% and 50% of the height of the columns.