Originally Posted by
c_m_shooter
If you plan to use it for off road, then get a tooth or two smaller than what you normally run SS.
+1 The conservation of momentum you get on a fixie just about cancels out the taller gearing in climbing. You'll also thank yourself on the downhills when you aren't spinning so fast. Riding fixed off road is incredibly fun and also rewarding in the skillset you will aquire. It will pay off on the trails and in traffic.
The cog gives a perfect chainline on my '07 'Cog9er. Oh, and mine's a drilled Dx cog. Only 3 holes, and disc bolts. For the record, water bottle bolts will fit, and are strong enough.
-Rob.