Hate those where you're off but not really sure what you did wrong- they just mess with your head IMO.
I'd prefer one where you just cocked it or hit a slippery bit of diesel or something where you can say "that was it, it won't happen again". when you aren't sure if you did anything wrong it's hard to get your riding up to speed again.
How do i know?
Very similar thing last year (RH side) on black ice.
At least I worked out where the ice was- I fell over again once I'd stood up after the off!
