A motorcycle chain comprises two precision ground pins peened at each end as a rivet, two bushes, two rollers and two side plates. A further pair of outer side plates join each link to the next link. In O ring chain a round seal is fitted on the pin between the plates to retain lubricant. The seal is contoured for less drag in X ring chains.
The Number of links is measured by the number of pitches, which is the gap between each pin or rivet and includes a Spring/clip or Rivet link to give an even number.

Chain Dimensions

Chain Dimensions

Metric Dimensions

wdt_IDChainPitch, mmWidth, mmRoller Diameter, mm
1 415 12.70 4.88 7.75
2 420 12.70 6.35 7.75
3 428 12.70 7.75 8.51
4 520 15.88 6.35 10.16
5 525 15.88 7.85 10.16
6 530 15.88 9.53 10.16
7 532 15.88 9.53 11.10
8 630 19.05 9.53 11.91
9 632 19.05 9.66 12.68

Side plate thickness varies with grade and make of chain. As a rule 1.5 to 2.6 mm. It is important for safety to join chain with the manufacturers correct Rivet Soft Link or Split Spring Link.
Size, Manufacturer, and grade is often stamped on some of the side plates.

British Classic Chain Sizes and Modern Equivalents

wdt_IDClassic SizeReynolds NoEquivalent
1 1/2 x 3/16 Inch 110044 Similar Modern 420 - See Below
2 1/2 x 5/16 Inch 110046 Modern 428
3 5/8 x 1/4 Inch 110054 Modern 520
4 5/8 x 3/8 Inch 110056 Modern 530

BSA/Triumph Bantam/Cub and similar earlier lightweight British motorcycles need a Original 1/2 X 3/16 inch chain.

This is because metric equivalents, although having the same pitch has different size rollers which will not correctly seat into the sprockets and will very quickly knock the tops off the sprocket teeth.
Many British bikes do not have sufficient clearance to fit Modern heavy-duty chain which tend to have very wide side plates.
Some British Classic bike run chains with an odd number of links. This is made possible by a special half link.

What’s the Difference Between 50 and 530 Chains?

Nowadays there is little to no difference between 50 and 530 chains, but the difference originated from where 50 chains were used in industrial applications whereas 530 chains were used primarily for transport and vehicles. Therefore 50 chains were traditionally more durable but heavier and more expensive. To avoid confusion many chains these days are in fact marked as 50 (530) chains.




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