I ride 4000 miles a year, do triathlons and duathlons. Did Ironman Canada in 1993. I’ve crashed twice….both stupidity on my part…and knocked myself out both times. (Broke my collarbone in one of them on RAGBRAI in 93.) I remember nothing about either crash. I was not racing, or going fast, or being reckless. Just nice, normal casual rides. Both times I hit my head hard enough to knock myself out…and I was WEARING a helmet. I can’t begin to imagine what would have happened if I hadn’t been wearing it.
I would not ride out of my driveway without a helmet. Nor would I allow my grandson to get on his bike, not even for “just a second” without a helmet. It saved my life.