Thank you all for your replies! Also Timmyt, I think I'm almost there it's either 16x43 or 16x44. No w need different advice, do I NEED perfect tension? One ratio is super tight, no slack, and the chain makes noises, the other is really slack, but the chain stays on decently. If I had to pick, what should I go with? Too tight or too loose? Can this hurt my bike? (Also I can't use a tensioner because it's a fixie)