Wilson Bicycling Science

Articles, guides, and products tagged "Wilson Bicycling Science" — a combined view of every catalogue resource on this topic.

User guide

Aerodynamics of an electric scooter as an engineering discipline: F_drag = ½·ρ·v²·CdA, decomposition into pressure/friction/induced/interference, Reynolds regimes (rider Re ≈ 10⁶, wheel Re ≈ 6×10⁴), CdA breakdown (rider 60-75% + frame 10-15% + wheels 5-10% + bag 0-15%), measurement methods (wind tunnel + coastdown ISO 10521 + power-meter Martin 1998), yaw-angle dependence Cy, why wheel aero on 8-10" differs from bike/moto, body-position tradeoffs vs stability, P_drag > P_roll crossover ≈ 19 km/h, fairings engineering and EU L1e, vehicle-class CdA table

Why a standing upright rider posture on an e-scooter is the worst CdA configuration among all personal vehicles (typical 0.55-0.70 m²), and why that means drag power begins to dominate rolling resistance from just 18-22 km/h — whereas a tucked motorcyclist only reaches that crossover at ~50 km/h. This article does not repeat the user-facing wind protocol from [Riding in windy weather](@/guide/riding-in-wind.md) and is not the same as the [energy-budget model](@/guide/real-world-range-energy-budget.md) — it is the **engineering foundation under both**: the formal drag equation F_drag = ½·ρ·v²·CdA with decomposition into pressure/friction/induced/interference, Reynolds regimes for the rider (L ≈ 1.7 m → Re ≈ 10⁶ at 25 km/h: turbulent boundary layer) and wheel (R ≈ 0.1 m → Re ≈ 6×10⁴: subcritical regime, drag crisis Re ≈ 3×10⁵ unreachable); CdA breakdown by component (rider 60-75% of frontal silhouette 0.4-0.55 m² + frame/deck 10-15% + wheels 5-10% + bag/cargo 0-15%), extrapolated from Crouch et al. 2017 J. Fluids and Structures 74:153-176 cycling aerodynamics state-of-the-art review and Bert Blocken et al. (TU/e + KU Leuven) bicycle-pose CFD studies; three measurement methods (wind tunnel low-speed automotive Eppler-section; coastdown ISO 10521-1:2015 + SAE J1263/J2263; power-meter regression Martin et al. 1998 J. Applied Biomechanics 14(3):276-291) with accuracy bands; yaw-angle dependence — Cy reaches 0.6-0.8 at 15-20° yaw, explaining catastrophic crosswind behaviour; wheel aerodynamics on small 8-10" wheels — why disc-vs-spoke difference is <2% drag (vs ~5% on 700c bike wheels) because of small frontal area; body-position tradeoffs — tucked posture possible but constrained by deck length and vibration absorption; power crossover P_drag > P_roll for CdA 0.55 + Crr 0.012 + m_total 105 kg at v ≈ 19 km/h (below it P_roll dominates, above it cubic P_drag dominates); fairings engineering — CdA reduction potential 25-40%, but crashworthiness penalty + EU L1e enclosure rules; vehicle-class CdA table for context (cyclist tucked 0.20-0.25; cyclist upright 0.45-0.55; e-scooter rider 0.55-0.70; motorcyclist tucked 0.30; auto 0.6-0.8). ENG-first sources (0 RU): Wilson «Bicycling Science» 4th ed. MIT Press 2020; Martin et al. 1998 J. Applied Biomechanics 14(3):276-291; Crouch et al. 2017 J. Fluids and Structures 74:153-176; Blocken et al. TU/e + KU Leuven cycling CFD; Hoerner «Fluid-Dynamic Drag» 1965; ISO 10521-1:2015; Anderson «Fundamentals of Aerodynamics» 6th ed. McGraw-Hill 2017; Schlichting & Gersten «Boundary-Layer Theory» 9th ed. Springer 2017; SAE J1263 and SAE J2263.

14 min read

User guide

Real-world e-scooter range: an energy-budget model (P_drag + P_roll + P_grade + P_accel), derating from payload / wind / temperature / altitude / tire pressure / speed, and how to convert Wh into kilometres

Why a manufacturer's nameplate range is almost always optimistic by 20–60 %, and how to replace blind trust in a marketing number with your own model: the full power equation (P_drag + P_roll + P_grade + P_accel; formulation from Wilson «Bicycling Science» 4th ed. MIT Press and Martin et al. 1998 Journal of Applied Biomechanics 14(3):276–291), drivetrain efficiency η_motor × η_controller × η_battery ≈ 0.55–0.75 over the full chain, six derating axes from real-world conditions (payload +1 kg → +0.5–1 % Wh/km; headwind 5 m/s at 25 km/h → +5.1× P_drag and ~+50–80 % total power; temperature from +20 °C down to 0 °C → −20–30 % usable Wh; –10 °C → −30–40 %; –20 °C → −50 %; altitude — air density ρ(h) = ρ₀ exp(−h/8400 m) gives −12 % drag at 1000 m, but motor cooling deteriorates from rarer convective air; tire pressure below 80 % nominal → +20–40 % Crr per bicyclerollingresistance.com data), a Crr table for e-scooter tires (pneumatic 0.008–0.015; foam-filled 0.020–0.028; solid honeycomb 0.022–0.035 — Cambridge UP / Design Society 2024 comparison + Wilson MIT Press inflated-tire baselines), manufacturer range testing standards (EN 17128:2020 PLEV by CEN/TC 354, UNECE R136 for L1e/L3e categories, SAE J1634 Multi-Cycle Test for EV range, WMTC worldwide motorcycle cycle), a worked example with Wh-to-km conversion, and a route-planning protocol. ENG-first sources (0 RU): Wilson MIT Press, Martin 1998, Schwalbe rolling-resistance technical notes, Bicycle Rolling Resistance Crr database, Cambridge UP / Design Society 2024 e-scooter tire study, EN 17128:2020 (CEN/TC 354), UNECE R136 e-bike type approval, SAE J1634 Multi-Cycle Test, Battery University BU-502 low-temperature discharge, NREL 2018 EV temperature derating studies, NCBI PMC9698970 Li-ion at low temperature review.

14 min read

User guide

Riding an e-scooter in wind: headwind / tailwind / crosswind / gusts — aerodynamic drag, range loss, lateral stability, route planning, Beaufort scale

Wind, for an e-scooter rider, is not a «secondary nuisance» but a separate physical axis that simultaneously hits five parameters: aerodynamic drag (P_drag = ½ρv³CdA, with ρ = 1.225 kg/m³ per ISA at sea level, and an e-scooter rider's standing-pose CdA ≈ 0.5–0.7 m² — close to the upright-cyclist values reported by Wilson «Bicycling Science» and Martin et al. 1998), range (a 5 m/s headwind at 25 km/h ground speed yields effective_v_air ≈ 32 km/h, equivalent to ~2 % gradient by the power formula, costing +20–30 % Wh/km), stopping distance (the vector sum of apparent_v with ground_v shifts effective speed entering a sharp corner with tailwind), lateral stability (lateral force F_y = ½ρv²A_side can reach ~2.5× the drag force per «Fighting crosswinds in cycling», a level that on bridges and in gaps between buildings — Venturi effect — becomes critical for 8–12-inch wheels with a short wheelbase), and gust response (transient lateral force with a 1–2 s rise time demands preemptive body posture). The wind discipline thus covers: drag-formula physics and CdA, behaviour in headwind / tailwind / crosswind / gusts, route planning around bridges / exposed stretches / coast, body posture (tucked vs upright tradeoff), gear choice (jacket flap, helmet visor) and a practical Beaufort table (Bft 0–8) with recommendations on when to ride, when to drop speed and when to dismount. ENG-first sources: Wilson «Bicycling Science», Martin et al. (1998) cycling power model, Bert Blocken (TU/e + KU Leuven) CFD studies on cyclist pose, UK Met Office and Royal Meteorological Society Beaufort scale, Fighting crosswinds in cycling (ScienceDirect), MIT urban canyon physics, BestBikeSplit / AeroX / Science4Performance CdA reference values, marsantsx / NAVEE / Apollo / Levy e-scooter range data.

13 min read