Sloped-for-rain urban sidewalks are horrible for wheelchair users because of the constant veering-off threat caused by gravity. Anybody who tries to self-propel a wheelchair on a city sidewalk for the first time is in for a rude awakening—the user must use one hand to steer by retarding one wheel, and that makes propelling inefficient, difficult and frustrating, to say nothing of the dangerous veering-off threat. Applicants solution is to provide joining means to couple and uncouple the drive wheels. The joining means, when coupled, causes the two drive wheels to rotate in unison preventing the wheelchair from veering-off so that it travels straight when traversing a sloped surface, and when uncoupled allowing the two drive wheels to rotate at different speeds to allow turning. Joining means comprises: slip-clutch, gear configuration or the like, and may be automatic or user controlled.
