I need to order a new rear cog for my conversion. I have 52 teeth on my chainring and was told to get an 18t cog. I want a nice "all around" ratio, I'll just be using the bike to cruise around. Can anyone give me some pointers or confirm that this is the right one to order before I do? I am kind of a noob when it comes to fixies but I'm working on it so any help would be great!