In the ratios you've posted above, the second ratio has four more teeth in the back and four less teeth in the front, compared to the first ratio. You should need the exact same chain length, and thus shouldn't need long dropouts at all.
(disclaimer: this makes sense in my head, but I've never tried it before.)
In the ratios you've posted above, the second ratio has four more teeth in the back and four less teeth in the front, compared to the first ratio. You should need the exact same chain length, and thus shouldn't need long dropouts at all.
(disclaimer: this makes sense in my head, but I've never tried it before.)