SRAM dual drive, 10sp cassette and 3 to 5 chainrings. 90~150 gear combinations possible.
That's what came to mind for me to.
Edit: Just remembered.. do it old school. 63 speed yo.
http://sheldonbrown.com/org/otb.html
Last edited by RaleighSport; 05-22-12 at 11:57 PM.