Originally Posted by
Retro Grouch
If you are going to use one of those chain checker thingies, you would be well advised to calibrate it against a brand new chain.
Or it might be better to compare the chain checker to a ruler, since you're more interested in the chain checker warning you that the chain is worn out (or approaching the end) than confirming that the chain is new.
My first chain checker was the Park CC-2. I found that on a new chain I couldn't even get the pins into the chain links(!). I contacted Park Tools and was told that the CC-2 is calibrated at the 1% mark. I've since found that this is basically true. I will notice when the reading is 0.75 and this trips the alarm to stock a new chain. The minute it hits 1.0 I replace the chain. By the ruler method, the chain isn't *quite* worn 1%. This has also been my experience with a Spin Doctor "go/no-go" chain checker and a Shimano
TL-CN42 (another "go/no-go" tool).
So basically I consider the chain check tools to be "advance-notice" devices, and they are faster and easier to use than a steel ruler, which means I check the chain wear a lot more often than I would otherwise.