You aren't providing enough info for us to really help you. Your gearing preference can change with your fitness level, time of year, steepness and length of hills, etc. Part of the skill of a SS/FG rider is knowing what gear to choose for the ride. It doesn't hurt to have a few different cogs (or a few different bikes geared differently). How does 48x17 feel to you? Thats a pretty typical gear ratio. Unless you are climbing monster hills, I'd start with that and move up or down later, depending on your preference.