Originally Posted by
asmac
2. At the risk of jinxing myself (so far so good) what is the most common cause of broken chains? Does the side plate or pin break or does the pin pull out of the hole?
I always (3-4 times in 16 years) had the side plate lose its grip on the pin and spring open in spite of not shifting under load, not splitting chains to clean them (so they were only joined once), and weighing under 140 pounds in good shape.
That stopped with the move to flush peened rivets. Shimano made the transition a long time ago, but Campagnolo didn't switch until 10 speed.