User guide
Helmets and protective gear for e-scooters: crash physics, the standards matrix, rotational mitigation, and FOOSH biomechanics
Engineering deep-dive into impact physics and certification mechanics for protective gear — parallel to the general regulatory overview in «Safety gear, traffic rules». Linear acceleration vs rotational velocity — HIC15 (NHTSA: 700 = 5 % risk of severe injury, 1000 = original 1972 FMVSS 208 threshold) and BrIC; the trade-off between peak force (kN) and duration (ms) as the central engineering parameter. Full standards comparison matrix: EN 1078:2012+A1 (1.5 m flat / 1.06 m curb, 5.42 m/s, 250 g max, single-impact), NTA 8776:2016 (~150 J, ≈ 6.2 m/s, written specifically for speed pedelecs up to 45 km/h), ASTM F1492 (multi-impact, flat + cylindrical + triangular anvils — a distinct skateboarding discipline), CPSC 16 CFR Part 1203 (2 m flat at 6.2 m/s / 1.2 m curb+hemispheric at 4.85 m/s, 300 g max), DOT FMVSS 218 (5.0–5.4 m/s, 400 g peak), ECE 22.06 (slow ≈ 6.0 m/s allows 180 g / fast ≈ 8.2 m/s allows 275 g), Snell B-95 (lower max acceleration, voluntary premium). Rotational mitigation technologies with physical explanation: MIPS (von Holst + Halldin 1996, 10–15 mm slip plane, up to −50 % rotational acceleration), WaveCel (inverted-V cell crumple, −16–26 % linear + up to 5× rotational reduction vs EPS), KOROYD (welded co-polymer tube structure, mostly linear, often paired with MIPS), SPIN. Virginia Tech STAR rating: 24 impact tests × 6 positions × 2 speeds, biofidelic linear + rotational combination. FOOSH biomechanics: the distal radius = 80 % of the wrist joint surface, Colles (pronation) vs Smith (supination) fracture patterns, Frykman classification; ASTM F2040 wrist guard splint design + prevalence (25 % of bone injuries in children / 18 % in the elderly / 8–15 % in adults). D3O dilatant shear-thickening polymer mechanism (Richard Palmer 1999) and EN 1621-1 Level 1 (≤ 18 kN mean / 24 kN peak — limb protector) vs Level 2 (≤ 9 kN / 12 kN) with a 5 kg striker at 4.47 m/s = 50 J. Back protectors EN 1621-2, eyewear ANSI Z87.1 / EN 166, retention test ECE 10 kg drop 0.75 m max 25 mm displacement. Fit protocol: two-finger above brow, Y-junction strap geometry under the ear, shake test, expiration 3–5 years (CPSC) / 5–10 years (Snell). The engineering source matrix runs parallel to existing applied-physics guides — braking, acceleration, cornering, climbing, descending, emergency maneuvers.