I've done 60 downhill on a commuter bicycle, and with the steering geometry forces being different downhill the bike gets uncorfortably unstable. I turned to take a driveway off the main road and the back end slid around, then caught suddenly, the rear wheel tacoed itself, i highsided and slid, ground through my shirt and jacket. Helmet kept my head safe, but I was in really rough shape and a little bloodied.

I see kids flying by helmetless on their tweaked scooters and ebikes. 🙏