@superbetsy I do not recognize the sign from anywhere at all but SOMEHOW I recognize the very specific fall it's depicting.

There is a tram laid out over the street pavement. The front wheel gets stuck in the tram tracks. The wheel is stuck really tough. Enough to twist the bike handle and rip it off of your hands and spin it violently against your elbows or ribs. Finally the bike topples with that twist and you fall face first to the concrete, your arms too numb to raise in front of you.