The bolts are very different. Chorus' top pivot is sprung. Athena's doesn't appear to be.
They are also about 8mm different in length.
Are you missing a bit? If the new bolt looks 8mm longer than the old one, is it going all the way through the dropout due to the B-Pivot spring retainer being missing? That could cause it to go loose after the thread has passed through the dropout, leaving the derailleur hanging from the thin section where the B-Pivot spring retainer and circlip should be.
Are you missing a bit? If the new bolt looks 8mm longer than the old one, is it going all the way through the dropout due to the B-Pivot spring retainer being missing? That could cause it to go loose after the thread has passed through the dropout, leaving the derailleur hanging from the thin section where the B-Pivot spring retainer and circlip should be.
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