im looking to purchase a new wheelset to convert my centurion super lemans into a fixie. When i measured the rear wheel spacing i got 135mm. Is that right? im reading 135mm is mostly mountain bike frames, so should i go ahead and order my wheels online and get 135mm?

also are cogs universal? if i order a 17t cog will it fit my hub?


as you can tell im new to the whole fg/ss scene.