We bought our sons larger bikes this weekend. Little Louis (2yrs) has a wooden balance bike but as it has no brakes I bought him a good S/H metal BB with a rear brake. Unfortunately he isn't good at using it yet and as we live on a hill he tends to fly off down the path and try and stop himself with his feet.
He wiped out at a low speed but ended up on his front (heavy coast on so ~ok) but his face (head down) scraped along the tarmac. Very fortunately his helmet has a large integrated peak/visor, not the clip on thing I have on mine. So his helmet has a large scrape on it and not his face. Note to self make him wear gloves in future.
I also popped out and got a snazzy HI VIZ top for Camie (4yrs) from the Workware shop at the top of Leith Walk. He likes to bomb around on his new 16" bike with full suspension (he calls is Spenchiun) and is getting more confident so does go off in the distance.