Abstract: Embodiments of the present invention provide a wheelchair for a wheelchair rider, the wheelchair having first and second wheel arms each pivotally mounted so as to allow the alignment of the first arm to move relative to the second arm through a range of relative alignment in response to the rider leaning laterally. First and second wheel mounts are provided on first and second arms respectively to mount respective first and second wheels with central axes of first and second wheels able to move in an arc about the point of pivotal mounting of the respective first or second arm.