Standard Harley chain pitch 5/8 x 3/8

The standard size for Harley-Davidson motorcycles from 1915 was 5/8“ x 3/8”. In the older parts manuals, often only the width is mentioned, so 3/8. Or you find a reversed size designation: 3/8“ x 5/8”. The chains themselves were already standardized, but obviously the naming was not.

3/8“ is the width between the inner plates and 5/8” is the center distance of the pins. Where does the designation 530 come from?

When the designation for roller chains was based on the sequence pitch x width, this was considered still too long. Malicious gossip claims that for some manufacturers this seemed not cryptic enough. Be that as it may, at some point you could read new designations. D.I.D. packaging was the first to sport these numbers: 630, 530, 428, etc. Meanwhile, all motorcycle chain manufacturers code their products according to this system: the first digit indicates the chain pitch in eighths of an inch. So 5/8“ → 5. The second and third digits indicate the width of the chain in ‘decimal eighths’: 3/8” → 3.0/8” → 30. Because widthwise, you may also find sixteenths of an inch, e.g. in the designation 5/8“ x 5/16”, which is then coded as 525, i.e. as 2-1/2 eighths. Because 5/16“ is 2.5/8”. How lucky we are that only 530 chains are suitable for Harleys and 520 chains for some custom applications!

How do I choose my new chain?

First of all, you need to know the size, but we'll assume you know that. The second criterion is the length. If you're not sure, count the links of the old chain. If you have changed or want to change the transmission ratio, calculate 2 links more or less for every 4 teeth difference on the rear sprocket. Or just use a longer chain and shorten it with a suitable tool.

The third criterion is the application. Roughly speaking, the difference between the 45 and its 20+ hp and a heavily tuned Sportster with a Buell engine. On the 45, a chain without sealing rings and with a clip lock is sufficient if it is well taken care of. For the aforementioned Sportster, it should definitely be a sealed chain with a riveted lock and the highest tensile strength available.