Sounds like you're describing an Ingo-Cycle:
http://www.bicyclemuseum.com/
Aldo Ross
Monroe, Ohio
> I have built a wheel like you describe. In maybe '73 a customer of the
bike
> shop I worked in brought in a vintage scooter, no pedals just a platform
to
> stand on. I have the vaguest memory that that brand was Fungo or Pongo or
> some such. It was built to have a massively off-center rear wheel, and
that
> was how you powered it down the road - by jumping on the platform in sync
> with the whole thing going up and down! The wheel was missing so we had
to
> build one.