Rigid B33 Primary Chain?

[leon bee]

It's 525 chain, correct? I thought so, then when I looked I kept seeing 520 chain everywhere and I don't know what that is. I've never bought any other than 530 for my other bikes and got confused. Thanks!

[Mike40M]

Your not the first to be confused. Motorcycle chains was earlier measured by pitch and width in inches. Since most people in the world are unfamiliar with thinking in fractions of an inch, a decimal looking system was introduced.
The first digit tells the pitch in eights of an inch. A 1/2" is now a 4xx and a 5/8" is now a 5xx chain.
The second and third digit tells width, also in eights of an inch. 1/4" becomes 2 eights, so x20. 5/16" becomes 2.5 eights, so a x25. A3/8" width becomes a x30.
So you are correct that your 1/2x5/16 chain is equal to a 525 chain.

[Mike40M]

Oops! Made an error. Last sentence should be:
A 1/2x5/16 chain is equal to a 425 chain.
Sorry

[leon bee]

Yes, I finally found a chart. 525 chain is for a 5/16" thick sprocket and 520 is for 1/4".