I know mine gets a bit noisy when I have the chain too tight - I wouldn't describe that particular noise as a twang, but maybe that's what it is. I'd say start with slackening chain slightly. A loose hub cup & cone might make a clunk if the wheel was far enough out of adjustment. I'd think you could hear something from BB if you yank on crank (the bike's, of course) when bike is in the stand...you'd surely "feel" some play if that was the issue. Anyway, good luck!