I've been experimenting with a modern Suzue two-sided hub (fixed and fw), trying to make Ed's old Bianchi fixed gear bike a little more versatile, and wound up with a 17/19 fixed gear on the fw side, and a 17-19-21 freewheel on the fixed side. Add some vintage steel wingnuts, and the whole thing is really interesting visually... see pics at:
http://albums.photopoint.com/
I'll have to grind the fixed cogs a bit to thin the "spacer" section, then mount the 19 backwards, to get as much thread as possible beneath the 17. Locktite is the preferred method of retaining track gears at MTV, where they've all but eliminated the use of lock rings.
Weight is 27oz, or 765grams!
Used with a 46x49 crankset, it should be able to handle even the hilliest local terrain.
65, 70, 73, 78 gear inches fixed 59, 63, 65, 70, 73, 78 gear inches fw
Aldo Ross