SuCalc
Health & Fitness

Cycling Power, Grade & Speed Calculator

Updated Aug 27, 2026 Reviewed Aug 27, 2026
Estimate steady cycling speed from power or required power from speed using grade, mass, distance, wind, rolling resistance, aerodynamics, and drivetrain loss.

Steady-state cycling physics

Enter rider, route and resistance inputs

Numerically solves the steady speed where available wheel power balances modeled resistance.

Positive climbs; negative descends.

Wind, rolling and aerodynamic settings

Positive is headwind; negative is tailwind.

Constant-segment planning model
Acceleration, turns, traffic, drafting changes, fatigue and braking strategy are excluded. Verify environmental and equipment inputs.

Result

Calculation summary

Enter values to see the result

Your result, breakdown, assumptions, and warnings will appear here.

Live road-segment preview

Power balances slope and resistance

power + wind+6%
The road graphic follows signed grade while the metrics update from the current steady-state model.
Available wheel power = gravity + rolling + aerodynamic power
Estimated speed
15.2 km/h
Crank power
250 W
Segment time
39:34

How to use this calculator

  1. 1Choose speed from power or power from target speed.
  2. 2Enter rider, bicycle, grade and distance.
  3. 3Review or edit wind, Crr, CdA, air density and efficiency.

Formula

Pwheel = (m·g·sinθ + Crr·m·g·cosθ + ½·ρ·CdA·vair·abs(vair)) × v

Positive wheel demand is divided by drivetrain efficiency; speed is solved from the same balance.

Calculation steps

  • Convert inputs to SI units and derive road angle.
  • Calculate gravity, rolling and signed aerodynamic components.
  • Solve speed or crank power and report braking demand separately.

Worked example

An 85 kg system on a 6% climb balances 250 W against gravity, rolling resistance and drag.

Assumptions

  • Speed and conditions stay constant.
  • Positive wind is a headwind.
  • Model parameters remain constant over distance.
  • Fatigue, handling and safety are excluded.

Sources

Frequently asked questions

Why do riders at equal power have different speeds?

Mass, drag, rolling resistance, grade, wind, air density and losses differ.

What does negative wind mean?

It represents a tailwind; positive represents a headwind.

Why can downhill rider power be zero?

Gravity can exceed resistance; the surplus is shown as braking power.

Is this a race-time predictor?

No, it models one constant segment without real-route pacing or interruptions.

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