Motorcycle chain

A motorcycle chain is the most common method used to connect and drive the rear wheel in a motorcycle. The others are belt drive and shaft drive.

Chain size is in inches, the three digit number used to discribe the chain size is based on the "rule of eights". The first digit is for chain pitch. This is the distance between the pins. The second and third digits combine for roller width, with a decimal point inserted between the second and third digits.

For example, a 420 chain has a pitch of 4/8" = 1/2" (12.70mm) and a roller width of 2.0/8" = 1/4" (6.35mm).

A 525 chain (the size my bike uses) has a pitch of 5/8" (15.88mm) and a roller width of 2.5/8" (7.94mm).

A 530 chain has a pitch of 5/8" (15.88mm) and a roller width of 3.0/8" (9.52mm).

There are a number of chain sizes in use, and chain manufacturers may have slightly different specs for roller diameter, sprocket width, etc. But a 525 chain from one manufacturer will have the same pitch as a 520, 525, 530, or 532 chain from another and run smoothly on any 525 sprocket from any manufacturer.

Modern motorcycles invariably use O-ring chains. This contrasts to the traditional roller chain. Using o-rings to seal the inner bearing surfaces keeps out foreign matter (dirt and water) and can translate to a useful life of 10-15000 miles.

Older bikes may not be able to fit the wider o-ring chain. Roller chain needs far more frequent lubrication and cleaning. Even with careful attention they will last less than 3-5000 miles before the wear of the chain will accelerate the wear of the sprockets.