Cycling Wattage
Estimate cycling power from speed, weight, gradient, drag. P = (Fg + Fr + Fa) × v. W/kg, FTP zone, CdA by position. Bradley Wiggins 440W hour record.
P = (Fg + Fr + Fa) × v
Gravity, rolling resistance, aerodynamic drag. CdA: hoods 0.32, drops 0.31, aero 0.29.
Preset Scenarios
Power Components
For educational and informational purposes only. Verify with a qualified professional.
🎯 When to Use This Calculator
Use when you don't have a power meter but want to estimate power from speed, or to understand power breakdown (gravity vs drag vs rolling). Helpful for comparing positions (hoods vs aero) and planning equipment upgrades. Also useful for calorie estimates.
Worked example
75 kg rider + 8 kg bike, 40 km/h, 0% gradient, hoods (CdA 0.32). v = 11.1 m/s. Drag = 0.5×0.32×1.225×11.1²×11.1 ≈ 268 W. Rolling (Crr 0.005) ≈ 45 W. Total ~313 W. Add 2–3% for drivetrain.
Cycling power P = (Fg + Fr + Fa) × v. Three components: gravity (weight × gradient), rolling resistance (Crr 0.002–0.03 by surface), aerodynamic drag (CdA: tops 0.408, hoods 0.324, drops 0.307, aerobars 0.2914). Bradley Wiggins held 440W for his hour record. CdA wind tunnel testing costs $500–2000.
📋 Key Takeaways
- • Bradley Wiggins: 440W for his hour record
- • CdA testing in wind tunnels: $500–2000
- • Rolling resistance varies 0.002–0.03 by surface
- • Aerobars CdA ~0.29 vs hoods ~0.32
💡 Did You Know?
📖 How Cycling Power Works
Power equals force times velocity. Three forces oppose the rider: gravity (on climbs), rolling resistance, and aerodynamic drag. At low speed, gravity and rolling dominate; at high speed, drag dominates.
Step 1: Gravity (Climbs)
Fg = mass × g × gradient. On 8% at 15 km/h, a 75kg rider + 8kg bike needs ~240W just for gravity.
Step 2: Drag + Rolling
Fa = 0.5 × CdA × ρ × v² × v. Fr = Crr × mass × g × v. Drag scales with v³; rolling with v.
Step 3: Sum and Convert
Total power = gravity + drag + rolling. Divide by rider weight for W/kg. Add ~2–3% for drivetrain losses in real riding.
🎯 Expert Tips
💡 Get Aero
Drops save ~15–20W vs hoods at 40 km/h. Aerobars save another 10–15W. Free speed.
💡 Tire Pressure
80–100 psi for road. Too high increases vibration losses. Tubeless allows lower pressure.
💡 W/kg for Climbing
4 W/kg = ~1000 m/h climb rate. 5 W/kg = elite. 6+ = world tour climber.
💡 Wind Matters
10 km/h headwind adds ~20–30% power at 30 km/h. Tailwind subtracts similarly.
⚖️ Power Calculator vs Other Methods
| Feature | This Calculator | Power Meter | Estimate |
|---|---|---|---|
| Physics-based formula | ✅ | N/A | ❌ |
| CdA by position | ✅ | N/A | ❌ |
| Component breakdown | ✅ | ✅ | ❌ |
| No hardware needed | ✅ | ❌ | ✅ |
| W/kg and zone | ✅ | ✅ | ⚠️ |
| Wind adjustment | ✅ | ✅ | ❌ |
| Calories estimate | ✅ | ✅ | ❌ |
📊 By the Numbers
📚 Official Sources
⚠️ Common Power Estimate Mistakes
- Ignoring wind—10 km/h headwind adds 20–30% power at 30 km/h
- Wrong CdA—hoods vs drops vs aero can change power 15–25% at 40 km/h
- Underestimating rolling resistance—MTB and gravel have 2–3× road Crr
- Forgetting bike weight—8 kg vs 12 kg matters on climbs
- Using speed from GPS—wheel speed is more accurate; GPS lags on accelerations
📐 Power Formula
P = (Fg + Fr + Fa) × v
Fg = m × g × slope (gravity)
Fr = Crr × m × g × v (rolling)
Fa = 0.5 × CdA × ρ × v² × v (aerodynamic). ρ = 1.225 kg/m³
CdA: hoods 0.32, drops 0.31, aero 0.29. Crr: road 0.004–0.006, MTB 0.008–0.015.
Pro tip: A power meter is the gold standard. This calculator is for estimation without one—useful for planning, comparing positions, or understanding the physics.
Understanding the three components—gravity, drag, and rolling resistance—helps you optimize position and equipment. Bradley Wiggins's 440W hour record required exceptional CdA and sustained power. Use this calculator to model different scenarios before investing in a power meter or aero upgrades.
⚠️ Disclaimer: This calculator provides estimates based on physics models. Actual power depends on many factors. Use a power meter for training. Not a substitute for professional coaching or equipment.