[sam_paine]

Two wheels gives it a turning radius of zero which is one of the breakthroughs.

Ever heard of a caster? (And not a fly fisher.)

[Don Joe]

"Ever heard of a caster?"

A caster is by definition an uncontrolled, passive device.

Comparing this scooter to a caster is like ridiculing powered flight by asking Orville Wright if he'd ever heard of a falling apple.