Originally Posted by
Polaris OBark
There is no way this could have happened without the OP noticing it at the time, if he was on the bike.
Either it happened when he was not on the bike, or there is much more to the story.
it could have easily happened without the OP noticing. ( see the missing Cervelo seat stay above.)
I’ve hit tons of sticks and never thought anything of them. OP could have easily hit some debris, thought nothing of it, and not noticed the crack for sometime. You could ride that bike for a long time in the condition pictured without feeling anything wrong.