So I just completed my first fixie conversion and I have a major problem. My chain keeps slipping on the rear cog and it seems as though it doesn't sync with each tooth. My chain line seems spot on and the tension seems fine. I am running a 40t and 14t cog and this brings about a total noob question, but does it matter what chain ring/cog size you run? Do they need to be a certain ratio so the chain is in sync with the amount of teeth? I don't know if any of this makes sense, but I really want my chain slip issue resolved bc I am super excited about this bike. Thanks a lot for the help.