So, a month after crashing and breaking my arm I'm still mulling over all the possible causes and trying to educate myself a bit to reduce the chances of it happening again. Obviously it's mostly a skill thing, but I keep coming back to the issue of rebound damping. It seems too much of a coincidence that, after six months of riding the bike with the controls in the middle and not having a single crash, ten minutes after basically removing all the rebound damping from the fork (1 or 2 clicks from fastest) I'm laying on the ground clutching my arm.
The crash happened when (after a decent compression) the front wheel skipped to the side and hit a rock that I'd intended to go round.
I know what too much rebound damping feels like (fork packs down), but how do you know when you've got too little?