So I have a noname flip-flop hub that was miraculously already on the bike I got for free from a friend's basement. I'm running it single-speed for now, but on the side with the two sets of threads I've got a track cog & a lockring on it. My problem is this: with the cog threaded all the way against the hub and the lockring threaded all the way to where the threads for the cog begin, there's still a 1-2mm gap between the two. I've torqued the lockring as much as I can (and the gap seems to be on the threads that the gear's on) and am wary of flipping the wheel & riding until there's no gap there any more, as I value not busting my ass. Any suggestions, short of Loctiting the thing on there or something?