Originally Posted by
Kontact
My example shows how roller wear alone can damage the sprockets. But roller wear AND pin wear don't cancel each other out - together they are going to produce the geometrical effect depicted in the graphic - that the pitch of the chain is effectively different when curved around a sprocket.
What examples do you have of chain checkers being wrong? How did you test that they were wrong?
And the whole 25% thing is a canard. It doesn't matter what the chain measures until that measure exceeds whatever tolerance the manufacturer recommends as "No go". We don't measure the chain to monitor its wear - that wear might not be linear. We measure the chain to take note of whether it is still in-spec or not. When it is not, you replace it to keep the rest of the drivetrain in shape.
I was not suggesting that roller and pin wear cancel each other out. I'm simply stating that chains don't exclusively wear on one or the other, which would be the argument that a ruler is not a good way to measure chain wear. If the chain is wearing, the rollers are wearing AND the pins are wearing and the ruler will show the latter, which is a good marker for roller wear as well. For years Campagnolo used simple elongation as the measurement for wear. While roller wear might be slightly more precise than just length, most chain checkers offer no real advantage over a ruler and several mislead the user.
Over the decades lots of people have reported their chain checker showing 75% wear on a brand new chain. That sounds wrong to me.