Motorcycle Chain Size Guide: 520 vs 525 vs 530

What 520 / 525 / 530 mean

These numbers are chain size families: pitch and inner-width combinations. Chains and sprockets must match the same family; a 520 chain will not run on 530 sprockets.

Smaller numbers generally mean narrower / lighter; larger means wider / tougher. Makers pick stock size for chassis and torque.

O-ring, X-ring, unsealed

Sealed (O/X-ring) chains hold lube and last longer; they are the street default. Unsealed chains claim less friction but need constant care; not ideal for most daily riders.

Clean and lube routine: How to Maintain a Motorcycle Chain: Clean, Lube, Tension

Sprocket teeth and gearing

Smaller front / larger rear sharpens acceleration and affects top speed and speedo calibration. ±1 tooth off stock is a light touch; big changes can break chain length and adjuster margin.

Chain + front + rear usually wear as a set. A new chain on hooked sprockets dies early.

When to replace

Excess stretch past the manual limit, stiff links, rust, damaged seals, and hooked sprocket teeth are replace signals. If slack is always at the adjuster end, the set may be done.

• Measure slack at the same point (manual mm range)
• Use a wear tool or maker stretch procedure
• New sets need correct pitch + link count + correct rivet/clip type

Wrong-size risks

A mismatched chain can jump, trash the gearbox, or cause a crash. Aftermarket ‘lighter 520 kit’ conversions are model-specific; do not improvise.

Log part numbers and km: RPMVault motorcycle garage