A friend has an e-unicycle (I think the category devices has some other name as well..) and he wanted to try out how it behaves in a track.

He sort of knew, but didn't expect it, that when the roll of the device exceeds a certain threshold, the device will shutdown. Even if you're on a curve going with some speed. Broke his wrist. Since then he's also wearing wrist protectors that keep the hand straight.

Actually it was a bit unexpected that it would have known to do that; it must have used its complete IMU data to even know it was rolled, as plain accelerometer would have been pointing "down" as usual.