This is ridiculous. He never hurt himself particularly (not even as much of a scrape as yesterday, and those didn't even bleed), but we're like, dude, put your feet down and slow down before you hit something. R. showed him the handbrake, but we're not convinced his hand is big enough to use it yet. We started actively praising him when he turned uphill to slow down before hitting something, or put his feet down to Fred-Flintstone brake, or dodge an obstacle or whatever. This seemed to influence his choices (altho maybe he was just running out of new things to experiment with hitting to see if those were fun ways to stop).
I shudder to think what's next.