Motorcycle chain length calculator

Chain sizes – what does 520 mean?

The three-digit motorcycle chain size is based on inch measurements:

• The first digit is the pitch (distance between pins) in eighths of an inch: 5 = 5/8" = 15.88 mm.
• The last two digits are the inner width between the plates: 20 = 2.0/8" = 1/4" = 6.35 mm.
• Smaller chains (04C, 25H, 219H, T8F, 270H, 35H) do not follow this code – their pitch is given in the table. The chain and sprockets must always have exactly the same designation.

* not an ISO/ANSI standard chain, dimensions may vary between manufacturers. Roller and pin dimensions may vary slightly between manufacturers (DID, RK, EK etc.) and chain types (standard, heavy duty, O-/X-ring).

How to measure the pitch?

The pitch is the distance from the centre of one pin to the centre of the next. If the chain has no marking, measure between the centres of two adjacent pins with a caliper: 12.70 mm is a 4xx chain, 15.88 mm a 5xx chain and 19.05 mm a 6xx chain.

Chain types – standard, O-, X- and XW-ring

Motorcycle chains are either non-sealed (standard) or sealed (ring) chains. Sealed chains differ in the cross-section of the rubber ring.

Standard chain (non-sealed)

The simplest chain with no seals between the links. The factory grease wears or washes out quickly, so the chain must be lubricated often.

• Pros: cheap; no seal friction, the chain runs most freely
• Cons: stretches and wears quickly, needs constant maintenance
• Use: mopeds, 50–125 cc bikes, vintage bikes and motocross racing, where chains are replaced often anyway

O-ring chain

Rubber rings with a round cross-section between the inner and outer plates keep the factory grease at the pins and dirt and water out.

• Pros: lasts several times longer than a standard chain, needs less maintenance (mainly the rollers need lubrication)
• Cons: the rings add friction, the chain is slightly stiffer
• Use: street and touring bikes, everyday riding

X-ring chain

The ring has an X-shaped cross-section, so the seal has four small lips instead of two large contact surfaces.

• Pros: clearly less friction than an O-ring, holds the grease even better, usually a longer life
• Cons: more expensive
• Use: sport bikes, powerful touring bikes, off-road bikes that need reliability

XW-, W- and Z-ring (manufacturer designs)

Top manufacturers (e.g. RK, DID, EK) have developed the X-ring idea further: profiles with several sealing lips protect better against dust and sand and flex so that friction does not increase.

• Pros: best protection and longest life
• Cons: the most expensive
• Use: enduro and long trips in dusty conditions, very powerful street and track bikes

Quick comparison