English Endurance
Climbing Power Calculator
Estimate the power required for a climb from distance, elevation gain, time, and total system weight. The model resolves the demand into its three physical components — lifting mass against gravity, overcoming rolling resistance, and pushing through the air.
Climb details
Power analysis
Enter the climb details above to see the power estimate.
Model assumptions
- Rolling resistance. Tyre tests publish a per-tyre figure at a 42.5 kg wheel load and 29 km/h. That fixes a rolling-resistance coefficient, Crr = Pref ÷ (42.5 × g × 8.05), which is then applied to the real conditions as Crr × m × g × cos(gradient) × speed. Because the whole system weight rests on both tyres together, this single figure already covers both — it is not doubled. A useful check: an 85 kg system at 29 km/h on the flat puts exactly 42.5 kg on each tyre, and the model returns exactly twice the published per-tyre number.
- Air conditions. Sea level — 1.225 kg/m³ density, roughly 20°C, no wind. Air density falls with altitude, so this overstates aerodynamic drag on high climbs.
- Rider position. Standard road position: 0.9 drag coefficient over 0.4 m² frontal area.
- Power type. Steady-state output. The model assumes constant speed with no acceleration, braking, or descending sections within the climb.
- Road surface. Smooth asphalt or concrete. Gravel, dirt, and broken surfaces raise rolling resistance substantially.
- Drivetrain. Losses are not modelled separately — the figure represents power at the wheel, typically 2–3% below crank power.
Interpreting the split. On a steep climb, gravity dominates and aerodynamic drag is nearly negligible — which is why weight matters so much and position matters so little. As the gradient flattens, speed rises and aerodynamic drag grows with the cube of speed, quickly becoming the largest term. The breakdown bar shows where the work is actually going on this particular climb.