Bob to Dan's idea of a ground friction propelled padalless bicycle aka a wheeled walker:
What, no Rohloff.
You don't need 14 speeds for a wheeled walker. Two will do. And Florian Schlumpf has already designed a sectionally circular two-speed planetary gearbox, same diameter and length as a bottom bracket, that you can have your choice of surgeon insert in each of your ankles. There's a Speed model, a High Speed or Butterfly Cadence model, and a Mountain model, each with a different ratio between the two gears. You operate this ingenious gearbox by jumping upwards off the saddle and klicking your heels together in the forward triangle of the frame, at the same time resisting the temptation to shoot your arm out in pseudo-military salute, then putting your feet quickly back on the road, ready for an adventure in a different gear. Sheldon Brown used to recommend it for those recently released from state institutions of the sort where electroconvulsive "therapy" is still practiced. See
http://sheldonbrown.com/harris/schlumpf.html (http://sheldonbrown.com/harris/schlumpf.html)
(http://www.schlumpf.ch/hp/schlumpf/bilder/g_faq.hsd.2.jpg)
Here is the Schlumpf two speed box fitted with chainring and a crank (1) to demonstrate that it can be used on more bicycles than the foot-dragger, but in the Danwhiz there will of course be no cranks and two of these gearboxes, fitted to either Dan's ankles or, for extra leverage, to his knees. The bottom bracket shell can be used to store the touring compass until designers work out what that hole is for...
More from Herr Schlumpf himself:
http://www.schlumpf.ch/hp/schlumpf/faq.getriebe.engl.htm (http://www.schlumpf.ch/hp/schlumpf/faq.getriebe.engl.htm)