They've got those opposing bolts like on Shimano hollowtech - and they must have worked loose. I was riding at the time, and thought the cleat was wobbling - went to unclip, and the whole crank came away, still attached to my shoe. Made stopping interesting!
Once re-tightened they never did that again, so I'm chalking it down to experience, rather than an issue with the cranks.
They've got those opposing bolts like on Shimano hollowtech - and they must have worked loose. I was riding at the time, and thought the cleat was wobbling - went to unclip, and the whole crank came away, still attached to my shoe. Made stopping interesting!
Once re-tightened they never did that again, so I'm chalking it down to experience, rather than an issue with the cranks.