Advanced Cycling Power Calculator

Enter Ride Details

Rider weight (kg)

Bike and gear weight (kg)

Target speed (km/h)

Distance (km)

Road gradient (%)

Use negative values for descents.

Wind speed (km/h)

Positive for headwind, negative for tailwind.

Air temperature (°C)

Altitude (m)

CdA (m²)

Typical road range is roughly 0.25 to 0.40.

Rolling resistance coefficient

Drivetrain efficiency (%)

Acceleration (m/s²)

Keep zero for steady pacing.

Cadence (rpm)

Gross efficiency (%)

Used for estimated food energy.

Example Data Table

Scenario	Speed	Gradient	Wind	Total Mass	CdA	Crr	Estimated Power	Notes
Endurance road ride	28 km/h	0%	0 km/h	80 kg	0.32	0.004	118 W	Steady flat pacing.
Climbing effort	24 km/h	5%	5 km/h headwind	80 kg	0.34	0.005	389 W	Higher grade dominates total demand.
Sprint surge	40 km/h	-1%	8 km/h tailwind	80 kg	0.30	0.004	291 W	Includes 0.2 m/s² acceleration.

Formula Used

The calculator estimates the total wheel power first, then adjusts for drivetrain efficiency to estimate rider power at the crank.

Relative air speed: v_rel = v_bike + v_wind
Aerodynamic force: F_aero = 0.5 × ρ × CdA × v_rel × |v_rel|
Rolling force: F_roll = Crr × m × g × cos(θ)
Grade force: F_grade = m × g × sin(θ)
Acceleration force: F_accel = m × a
Wheel power: P_wheel = (F_aero + F_roll + F_grade + F_accel) × v_bike
Rider power: P_rider = P_wheel ÷ η
Torque: T = P_rider ÷ ω, where ω = 2π × cadence ÷ 60
Air density: Estimated from altitude and temperature using a standard atmosphere pressure model.

How to Use This Calculator

Enter rider weight plus the bike and gear weight separately.
Set the target speed and planned distance for the effort.
Add road gradient, wind, temperature, and altitude values.
Enter CdA, rolling resistance, and drivetrain efficiency inputs.
Leave acceleration at zero for steady riding.
Add cadence to estimate torque at the crank.
Click the calculate button to show the result above the form.
Use the CSV or PDF buttons to save the output.

FAQs

1. What does this calculator estimate?

It estimates the rider power needed to hold a chosen speed after accounting for drag, gradient, rolling resistance, acceleration, and drivetrain losses.

2. Should I include bottles, tools, and clothing weight?

Yes. Add all carried mass to the bike and gear field because extra weight increases climbing, rolling, and acceleration demand.

3. How should I enter wind speed?

Use a positive number for headwind and a negative number for tailwind. This directly changes relative air speed and aerodynamic power.

4. Why does speed affect power so strongly?

Aerodynamic drag rises quickly as relative air speed increases. On flat roads, that drag often becomes the biggest part of total power.

5. What is CdA?

CdA combines drag coefficient and frontal area. Lower values usually mean a more aerodynamic position, tighter clothing, or faster equipment setup.

6. Why is cadence included?

Cadence lets the calculator estimate crank torque. Two riders can produce the same watts, but lower cadence usually needs higher torque.

7. Does altitude change the result?

Yes. Higher altitude usually lowers air density, which can reduce aerodynamic drag and the power required at the same speed.

8. Can this replace a power meter?

No. It is a planning and estimation tool. A power meter measures real output directly and captures pacing changes, terrain shifts, and rider technique.