Check out my new 'no-push scooter' page. It is a summary of a project I did at the end of last summer - a scooter that you can propel by jumping up and down...."Last summer I read a description of an old-fashioned bicycle whose main mode of power transmission was not by chain, but by an off center (eccentric) wheel. To make the bicycle go, the user would simply jump up and down powering the bicycle similarly to how a locomotive is powered by pistons which move back and forth."