Caporegime
I can't tell from the photos provided, but would it be possible to route the chain the wrong way through the jockey wheels or something? Short of trying it myself, I can't tell quite how wrong you could get it or if it would even work or what the end result would be, but it leaps to mind as a potentially easy mistake to make. I once put my chain on after a clean and got it the wrong side of a metal tab between the two jockey wheels and it made a racket and didn't shift properly. I noticed pretty quickly, though, so I don't know whether it could have as dramatic results as in the photos.
Anyway. If this problem has arisen in the time it's taken to get the chain off and on again, I'd guess at chain routing being the problem, assuming you didn't randomly hit the derailleur with a hammer midway through the process.
Anyway. If this problem has arisen in the time it's taken to get the chain off and on again, I'd guess at chain routing being the problem, assuming you didn't randomly hit the derailleur with a hammer midway through the process.
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