I experienced my first broken chain the other day. One of the outer plates popped off the rivet and made a horrible racket when it went through the rear derailler. Thankfully it didn't completely fail or I no doubt would have eaten the top bar on a very hilly ride. Post incident analysis revealed that the failure occurred where I had rejoined the chain to add a few links for a larger freewheel, so it was a link that had been removed and reattached, by me. There was also some bulging of the area around the hole in the outer plate. I can only deduce that I screwed up putting this link back together and caused the deformity by not having everything perfectly aligned when I put the chain back together. I figured better safe than sorry and replaced the link that failed, but it took me three tries to get the stupid thing back together without causing some deformity around the hole where the pin goes into the outer plate. Is there some trick to getting the holes and plates and pins aligned correctly that I am missing? It seems like every chain has a little variance in the shape of the outer plates, maybe this one just doesn't fit my chain tool correctly? I bet I have done this a couple dozen times without a problem, but this particular chain is being difficult.