Valve for tubeless bicycle tires

A valve for tubeless bicycle tires destined to be mounted in a circumferential seat (50) formed in the peripheral part of a rim (5) of a wheel, the valve comprising a mechanism (3) for the passage of air for inflating/deflating the tire, a valve body (2) containing the mechanism (3) and destined to be housed in a hole (52) formed in the rim (5) and communicating with said seat (50) for accommodating the tire, a gasket (4) with a substantially frusto-conical shape to ensure the tight seal of the valve body (2) inside the hole (52) in the rim (5).