I upgraded gears and shifters on my folding bike recently, and went with the 10sp Tiagra (flat bar). Initially I was going to go with mtb style shifters, but once installed the shop realized they wouldn't work with the derailleurs I had on the bike. Don't quote me, but in the end I think they told me you can use mtb derailleurs with road shifters, but not mtb shifters with road derailleurs. Something to do with the spacing of the gears?