+1. Try 22T first. It's easy enough to change if you want it a bit taller. There's no telling what cog you prefer until you spend some time riding with it. I have a box full of em. I'm happy with the 48x22 gearing on my Rudge in hilly New England, but I'll change to 48x18 when I visit Florida this winter. I won't shorten the chain, I'll keep it so I can swap back easily.