I'm building a fixed gear using an old threadon road hub with a Dura Ace track cog. I've build others but always used Surly cogs which apparently are thinner at the threads by 1.5mm or so than the Shimano. I've always used a bottom bracket lock ring and loctite with the Surlys for extra security to prevent the cog from unscrewing when I torque back the cog to slow down (using a front brake, no rear brake).
My problem is this- the thicker Dura-Ace cog does not leave enoungh threads on the rear hub to allow the use of a lockring. I've never had a problem with a cog unscrewing with my usual setup with the lockring. I would like to build my rig with no rear brake, just using the Dura Ace cog, loctite, but no lock ring. My question is a little bit of engineering science. Is a thicker (more threads) cog less secure (more likely to unscrew) than a thinner cog used in combination with a lockring? Assuming that the total number of engaged threads is approximately the same, is the resistance to the backpedaling torque going to be the same? Remember, this is not a track cog with reversed threading for the lockring-