Originally Posted by Chinookmark
What about two sets of sprockets mounted, and a slider with a handlebar lever, like the gear change on a bicycle? It would be like a two speed, but actually be a twelve speed.
A bicycle has a rear derailluer that acts as a chain tensioner. I'm not sure you could develop a tensioner that would be tensioned enought to withstand an 800cc motorcycle, yet, be slack enough to allow it the chain to climb to the higher gear. Also, the rear cassette has teeth shaped in a specific way, on a bicycle, to get the chain to climb the gears. Lastly, a motorcycle chain is designed to be ran only in a straight chainline, whereas a bicycle chain is designed to be cross-chained.