Chain and Sprocket Calculators
The chain calculators below do not have allowances in the calculations for the chain slack required by the geometry of the rear suspension. They rely on the allowance for slack BMW allowed in the standard chain and sprocket set.
The chain is 112 links of 520 (5/8" x 1/4")
There are minor differences in roller and pin diameters
between manufacturers and chain types so be warned.
When calculating the number of links needed in a chain, the centre to centre distance between the sprockets is needed. For the standard sprocket set BMW calculated the number of links needed and allowed for chain slack to suit the suspension geometry. This length can be used to make calculations for non standard sprocket sizes
Enter the front and rear sprocket sizes and the number of links to calculate the sprocket centre to centre distance.
Front Sprocket
Rear Sprocket
Number of Links
Distance C to C
The distance between sprockets for the standard GS chain is 24.966 inches. This figure can be used to calculate the number of links needed in a chain when using different sprocket sizes. Add 0.75" when fitting an 18" rear wheel.
Enter the front and rear sprocket sizes and sprocket centre to centre distance to calculate the number of links.
If your result is an odd number of links add one link to get an even number
Front Sprocket
Rear Sprocket
Distance C to C
No of Links
The calculation of chain length is easy and measurement is worthwhile in determining chain wear.
Regina Chains
are more forthcoming than other manufacturers on wear and technical data. Some of the mild steel rear sprockets
supplied with kits will wear out well before the chain and front sprockets. There are circumstances where
replacement of the rear sprocket only is appropriate. The initial length of a chain can be calculated below.
TR650