Adding another fixed cog would be inadvisable, especially if you're not using your brakes to slow down, as the threads on the other side of the wheel are for a freewheel. Sheldon's take:http://www.sheldonbrown.com/fixed-co...l#freewheelhub.

The Steamroller's stock gearing is pretty low at 65 inches, however. The standard practice on a fixed gear, and hence why you have a flip-flop hub, is to have a higher gear, around 75-85 inches oftentimes, on your fixed side for bombing around and a larger freewheel (for a lower gear) on the freewheel side for bailing out when you're tired.