Originally Posted by
79pmooney
Another approach - try what you've go. Change the chainring. Shift into small-small. Does that work? I'm guessing the derailleur cage will be roughly straight back and unable to get full tenison of the chain. The chain may be hitting itself. But neither of these is a deal breaker if it doesn't bother the matter between your ears. It is a gear that you shouldn't be using very much. Working but meeting nobody's idea of kosher is OK.
...
Ben
Exactly; as a sadist who insists on brutalizing all my RDs to their extreme limits, I feel trial and error is the surest way to calculate your chain wrap. It's especially fun on bikes with really long dropouts. It really expands the possibilities, if you're not afraid to mess with chain lengths.
"OK, let's see what this little sucker can handle..."