Originally Posted by
fietsbob
I can use the chain checker to measure..
or measure a foot of length.
every link pin was at 1/2" centers when new,
so combined wear is how much longer 12" of chain is than 12" ...
1% is definitely worn, so 0.125 inch = 1/8 inch.
Some like to replace at 0.5% which is 1/16 inch.
I split the difference and change at around 0.75%.