Originally Posted by
smd4
You mean the wear from the inner plate? If there's wear between the pin and outer plate, why doesn't the pin fall out eventually?
I circled the obvious lip on the top and bottom of the pin. The pin stands proud of the outer plate on all chains. You can see a small lip just below where the outer plate has worn the pin slightly. The pin is worn more severely from the inner plate but the pin is also worn from the outer plate rotation. The reason the pin doesn’t fall out is because the lip traps the pin to keep it from falling out. Additionally, the rate of wear on the outer pin is slower than the inner pin and few chains really get to this kind of wear. Further, modern chains from at least 9 speed on are peened to keep the chain from pushing the plate off the pin. That’s what pins should not be reinstalled on almost all modern chains. Plates falling off the pin
was an issue in the era of transition from 8 to 9 speed (or perhaps 7 to 8) two to three decades ago. Chain breakage (from pin failure not cracking) was far more common than it is today.
