(The) three reasons for falls

[Setonix]

@Quax1974

Missing one that can be really nasty: the slow or zero-speed fall.

Typically when learning to ride or (practicing) mounting.
Resulting in falling onto the unicycle or onto your back by having a pedal preventing you from putting a foot down.

I hate the instability of zero speed!

Edit: to put it as a reason for falling: lack of speed

That is exactly what happened to me today when training to ride backwards. I go too slow or start thinking too much while I slow down. Got a nasty pedal bite today as well. I refuse to learn with pedals without pins though.

[johnfoss]

@wobbling_bear

A molecule train crossed your path: you just fall and you wonder why

Way back when Bruce Bundy, who is probably not remembered by many contemporary unicyclists, was a new (but really talented) rider, he and his friend had a name for this; they blamed it on cosmic rays.