I recently converted one of my steel bikes into a fixed/single-speed. Not sure if I will like the SS as it is pretty hilly where I live, but I'm going to give it a shot. However, if don't like it, my plan is to convert it to a 1x9. When I did the SS conversion, I removed the outer chainring and replaced the inner ring with a 42 T. The 42 ring seems like it would provide a nice range of gears coupled with a 12-27 cassette.