A wheelchair comprises a frame and first and second rear wheels that are each independently mounted to the frame via a respective mounting hub. Each rear wheel is detachably mounted to its respective mounting hub at two or more distinct hub mounting points. Either or both of the hub mounting points can be movable with respect to a remainder of the hub, for example via a pivoting arrangement. A disk can be positioned at the rear wheel and a stop element located at the mounting hub can be selectively operated to interfere with the disk to prevent rotation of that rear wheel. The frame can comprise first and second spaced apart and unitary tubes which each extending in an unbroken manner from a wheelchair seat to a wheelchair forward region.