Originally Posted by
sweeks
Years ago when I got my first chain check tool (Park CC-2) I noticed it wouldn't fit into a new chain. I contacted Park and was told that the tool is calibrated at the wear limit (1%). I've since found that the tool agrees well with other tools and the ruler method for worn chains. There's some technicality about inaccuracy of these kinds of gauges which is supposedly only compensated for in a tool made by Shimano. I have one of those as well, and it agrees with the others. I'm comfortable using any of these to identify a chain that's approaching the end of its useful life, but the ruler method is more accurate.
My Shimano tool measures 0.40-0.50 while my other tools indicate 0.75 for the same chain, so they do not match. When you measure with those chain tools, you are either relying on whether or not they are bent, or their assumptions on roller thickness (except for the Shimano and Pedros). The most accurate way to measure is with calipers. And taking 2 or 3 samples at different sections of the chain. This method of A-B also cancels out any errors from the calipers (assuming that the measurement is taken in the same way for both A and B).
