I may be more relaxed than the 'typical' fixie rider, so I run a 38 / 18. I do have a 17% grade I have to climb & descend in order to leave my neighborhood to the west, so I've adapted to be able to spin reallllly fast during the descent. If I ran a 46 / 16 the descending would be less of an issue, but I'd be a lot less happy most of the rest of the time.