Originally Posted by
nashcommguy
My combination is 48x16 fg. Not sure how to compute gear-inches. It's an old Fuji conversion w/a Sugino 103mm bb, Messenger cranks, Rocket Ring and a Vuelta wheelset. My favorite bike by far. Seatpost rack/trunkbag combo hauls empty containers and clothes on the homeward leg.
Try
Sheldon's Gear Calculator. Not only can you figure gear inches, but also ratios and it'll even tell you speed based upon your cadence.