I just got a bike that had a 15t front sprocket on it, I want to take it back to the stock 16t. I was looking at sprockets and they are relatively cheap. However the sites I was looking at said they had the sprockets for a 520 or a 525 chain. How do I know which one I have? Is it marked on the chain somewhere?

 

Clean off a link, usually have the manufacturer and type on there.

 

You can also measure the width of the roller on the chain. A 520 will be 1/4" wide, a 525 will be 5/16" wide, and for good measure, a 530 will be 3/8" wide.

 

there's no markings on the chain and I don't have a tool to measure that precisely. guess i'll have to take it to a shop and have them tell me.

 

How thick is your rear sprocket ? The thickness of the sprocket would match the width of the pins in the chain.

 

don't know if it's written on their either. i'll have to check.

 

The general rule of thumb is to replace both sprockets and the chain together. By not doing this you will wear out the chain and sprockets faster. Also by changing them as a set you will not have to worry about what size you currently have nor will you have to take it to a shop to have them tell you. If you are positive that the chain and back sprocket are new/in very good condition then you can get away with just the front. A new set is not all that much and would put your mind at ease.

 

i know but i don't have money for all that.

 

Yeah I hear you on that but you're going to be super pissed if you have to replace it again pretty soon cause chain wore it down prematurely. Also does your bike have a speedohealer on it?

 

no, I would much rather keep the 15t sprocket and put on a speedohealer, but as already stated, I don't have that kind of cash. So i'll just throw on a 16t sprocket for now. it'll get me by until I can get some more cash.