A manually propelled vehicle (1) comprises a frame (11) and a plurality of wheels (17, 23) secured to the frame (11) for conveying the vehicle (1) in one mode of operation. The vehicle (1) further comprises at least one continuous track assembly (3) mounted on the frame (11) and defining an upper tread (63a) and a lower tread (63b). The distance between the upper tread (63a) and lower tread (63b) can be changed from a retracted condition to an extended condition. In the extended condition, the lower tread (63b) forms the ground engaging surface of the vehicle (1) for conveying the vehicle (1) in a second mode of operation thereof. The vehicle (1) further comprises a seat (5) pivotally mounted to the frame (11) and means to tilt the seat (15) rearwardly when ascending or descending an incline
