Why does drag matter so much in cycling?

At speeds above 25 km/h, aerodynamic drag is the largest resistance force. At 40 km/h it accounts for 80-90% of total resistance on flat ground.

How does speed affect drag power?

Drag force increases with the square of speed, but drag power increases with the cube. Doubling your speed requires eight times the power to overcome drag.

Standard sea-level air density is 1.225 kg/m³. It decreases at altitude and in warm weather, and increases in cold weather.

How can I reduce my drag?

Use an aero position, tight clothing, aero helmet and frame. Even small reductions in CdA yield significant power savings at speed.

BikeCalcs

Drag Calculator — Aerodynamic Drag Force

Calculate aerodynamic drag force at different speeds.

Speed

CdA (Drag Area)

Drops ~0.32, Hoods ~0.38, TT ~0.24

Air Density

Sea level ~1.225

How We Calculate This

Aerodynamic Drag Formulas

Drag Force (N) = 0.5 x air_density x CdA x v²
Drag Power (W) = 0.5 x air_density x CdA x v³

Where v is speed in m/s, air_density in kg/m³ and CdA in m².

Frequently Asked Questions

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CdA Calculator

Estimate your drag coefficient area from field test data.

Wind Resistance Calculator

Calculate the effect of headwind and tailwind on power requirements.

Last updated: February 2026

All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.