from wikipedia http://en.wikipedia.org/wiki/Chainless_bike

A chainless bicycle is a bicycle that transmits power to the driven wheel through a mechanism other than a metal chain.

Examples:

* Directly driven "ordinary" bicycle (see Penny-farthing)
* Shaft-driven bicycle
* Belt-driven bicycle
* Hydraulic bicycle (and pneumatic bicycle)
* Hybrid vehicle (see Series hybrid bicycle)
* Some rowed bikes use a cable or a linkage.
* Stringbike the pulley-driven Hungarian designed bike