User guide
Cornering on an electric scooter: lean angle and centripetal force physics, countersteering at ≥15 km/h, body position, line choice, surface hazards (tram rails, paint, sand), tire pressure, common mistakes + practice drill
Cornering on an e-scooter is not 'turn the bar that way.' It is a sequence of four independent mechanisms: (1) leaning at θ = arctan(v²/(r·g)) — for a 10 m radius at 20 km/h this is 17°, at 30 km/h it is 35°, at 40 km/h it is 52° (beyond a normal tire's adhesion); (2) countersteering above ~15–20 km/h — a brief push of the bar in the opposite direction initiates the lean, and this is physics, not an alternative to leaning; (3) body position with the scooter's high CoG (centre of mass 20–25 cm higher than a motorcycle at the same wheelbase) — knees bent, weight forward on entry, eyes on exit; (4) outside-inside-outside line with a late apex — this increases effective radius and cuts required lean by 5–10°. Plus surface hazards that turn a routine corner into a crash trigger on a single-track vehicle: tram rails at an angle < 30° (the critical threshold, PMC 10522530), painted road markings with glass beads (Minnesota DOT — the lowest COF of all road surfaces), sand/gravel on off-camber surfaces (front-wheel washout), tire pressure as a switch between contact patch and rolling resistance. Helsinki TBI cohort (2022–2023): e-scooter riders end up in ED 3× more often than cyclists at the same intersections. Ten sections — physics, countersteering, body, lines, surfaces, tires, trail braking, mistakes, drills, recap.