So I have another noobie question. In order to try out SS I bought a cheap Nashbar spacer/tensioner kit. I've noticed that the "nut" that holds the spacers and cog on the freehub is not notched like most ones that come with a cassette are. Obviously it doesn't click when you tighten it. Any chance it could work loose?

I have an old cassette all broken down and am considering using the smallest cog from it in place of the last spacer. It fits on the half splines nicely and the matching "nut" confidently clicks into place. However I really don't want to do this unless loosening could be a problem.

edit: "nut" = lockring, Duh