Two-wheeler

thumb|right|Penny-farthing bicycle A two-wheeler is a vehicle that runs on two wheels.

The two wheels may be arranged in tandem, one behind the other, as with single-track vehicles, or arranged and also side by side, on the same axle. If on the same axle, the vehicle may have no other support, as with dicycles, or have additional support, which is often also the source of motive power.