Originally Posted by
Gabuyo
If it is any help, the bike is a stock Mercier Kilo TT which I have heard to have a reputation of not having the greatest stock lockring.
Apparently this bike has a flip-flop hub. Which hub is this? Does the fixed-gear side have a reverse-threaded lockring?
If you feel it slipping in the forward direction, you must stop and tighten up the lockring before going in reverse. Going back and forth repeatedly will just loosen the lockring and cog more and more.