Thanks ismellfish2,
As I said, I'm still trying to figure all this stuff out. After reading other people's comments online I was under the impression that unless the chain was almost perfect it would derail if you hit a bump hard. Good to know.

Yeah, I am actually a little more concerned with chainline but was saving that for another post. I would like to use a single speed MTB hub to keep everything simple and minimalist but not sure it would work with a track crank. And I really don't mind using a cheap freehub cassette and spacers, because I know it shouldwork.