There's a lady I know who is in a wheel chair and still 'rides'.
Ok well maybe rides a bike is not descriptive enough.
She's got on old Z1 with a side car arrangement on it. All the controls have been moved to the side car. She simply wheels herself into the side car, straps the wheel chair in and 'rides' away. It's not pretty engineering by any stretch of the imagination, but it's effective. I'll see if I can track down a picture.
It's quite disturbing the first time you see her coming towards you because there's a bike and sidecar coming towards you, but there's no one on the bike.