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If they were all breaking, we'd have found out by now.
The ones which broke and gave Crack'n'fail their nickname aren't around any more. While the design is obviously dodgy, any which have survived are probably free of what was most likely a sporadic rather than systemic issue. Just from looking at them, they seem like a design which would be very vulnerable to stress raisers at weld imperfections.
Do we trust this old Cannondale dropout design? It's always seemed mad to me.