Been ages since I played some bike game demo's and its time to lighten up a little:
Cnet have a demo version of that old Fave - Ducati Racing world:
http://downloads.cnet.co.uk/0,39100207,39176004s,00.htm Only one track and it never did quit properly, even in the version I had on CD but its still fun for a small game.
Cnet also have a demo of MotoGP but its 150Mb - I set it away last night - looks great but I gotta dig a controller out for that one.
Finally - great looking ad site for a game - but no media downloads
http://www.super-bikes.blackbeangames.com/ Cheers - Frank