...if so, what size do you roll on the rear- 18? 16? still learning the ropes, and my new rig comes built with a 50t sugino chainring, with no rear cog. i live in Hawaii, so steep SF-esque hills are nonexistent. i plan to do a lot of distance rides (well, i AM on an island, so its not the type of distance im sure most of you are used to) . i need so advice on whether to keep the 50t, and if so, what size cog to run. if i should indeed switch my front ring out, what size would you recommend for flatland rides? thanks guys.