I don't know a whole lot about the chain and sprocket other than its purpose. Since mine is getting pretty bad I'm in the market for a new one, but would like to know more about my options.

What are the advantages of changing the teeth numbers?

What is a 520 chain?

What are some good brands and bad brands?

Should I just get another OEM?

Any other information about the chain/sprocket would be wonderful too. Thanks for your input.