Most of the break surface is weathered and corroded. Only a very thin sliver of metal is what made the final separation today, which is why the seat came off while he was "just riding along". The rest of the break occurred over a long time due to fatigue.
This is a good reason to carry a spare seat bolt or to replace the seat bolt periodically since it's difficult inspect for cracks in the metal parallel to the bolt's threads.
Exposure mode: program (auto)
Metering Mode: matrix
Exposure time: 0.0012 s (1/800)
Focal length: 10.4mm (35mm equivalent: 28mm)
File size: 1548840 bytes
Camera maker: SONY
Camera model: DSC-RX100
Resolution: 2833 x 1889
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