Normal riding, once was on a flat road on an ordinary city bike (saddle ~same height as handlebars, not full tuck like a racer), the other was downhill on a mou

Normal riding, once was on a flat road on an ordinary city bike (saddle ~same height as handlebars, not full tuck like a racer), the other was downhill on a mountain bike (on asphalt). In both cases I flipped over the front, because the front wheel turned perpendicular to the direction of travel. I average around 20-22kph on my 8km commute riding my current bike. It's nothing particularly special, just an 8-speed city bike, and I certainly don't go all-out, I ride at what feels like a comfortable speed for the bike. Biking in Copenhagen, I definitely see a fair share of people on granny bikes dawdling along, they're much more likely to crash due to sudden mechanical failure, or due to inattention from staring at their damn phones. But either way, we're only talking about solo accidents. You can certainly also hit your head against the hood of a car, for instance. Besides, I like wearing the helmet. It concentrates airflow across the top of my head, and it gives me more area to put stickers on.