The present invention provides a wheelchair, in which the angular position of a swivel axis of a castor wheel with respect to the frame of the wheelchair is adjustable in a continuous, step-less manner. In general, a castor wheel assembly (14) is connected by way of a transversal axle (16) to a frame portion (18). Separately, an adjustable blocking mechanism (22, 23) prevents said castor wheel assembly (14) from pivoting by blocking the castor wheel assembly (14) at the desired angular position.