If a worn chain is replaced by a new one, the number of chain links must be determined. Since a worn bicycle chain has lengthened and the pure holding of the new and old chain together leads to an inaccurate result, thus to a different number of chain links.
suitable for bicycle chains from BMX to 12-speed
Attach chain link counter to chain, set counter to zero
Mark any chain link with a visible point
From chain marking 1x pass through chain link counter
Read off the number of chain links
Count new chain from chain reel with chain-link counter and cut the chain to length (the new chain is shorter compared to the worn chain)