Cycling Power → Speed Calculator
Physics-based speed from watts: air drag, rolling resistance and gradient, with honest defaults.
The cubic term explains cycling's economics: on the flat, doubling speed needs ~8× the aero power, so position (CdA) buys more speed than fitness at race velocities. Tilt the road 8% and the v³ term fades — now it's all W/kg. 200 W on the hoods ≈ 30 km/h flat; the same watts at 8% ≈ 9 km/h.
Formula
For general information only — not medical or training advice. Estimates vary between individuals; consult a qualified professional before changing your exercise or nutrition routine.
Physics-based speed from watts: air drag, rolling resistance and gradient, with honest defaults. The Cycling Power → Speed Calculator is a free, private cycling power speed tool — every result computes instantly in your browser with no sign-up and no data upload.
About Cycling Power → Speed Calculator
The cubic term explains cycling's economics: on the flat, doubling speed needs ~8× the aero power, so position (CdA) buys more speed than fitness at race velocities. It applies P = ½ρ·CdA·v³ + (Crr·m·g + m·g·grade)·v (solved for v). Use the Cycling Power → Speed Calculator to get an instant, clearly-explained result with the working shown step by step — free, private and with the source method cited.
How to use Cycling Power → Speed Calculator
- 1Enter your details in the Cycling Power → Speed Calculator input fields above.
- 2The result updates instantly with the working and reference bands shown.
- 3Adjust any value to explore how it changes the outcome — it's free and unlimited.
Why use Cycling Power → Speed Calculator?
- ✓Instant cycling power speed result that recomputes as you type — no waiting, no page reloads
- ✓100% client-side: your health data never leaves your browser
- ✓Shows the actual formula and your numbers substituted in, so you can see exactly how the result is reached
- ✓Based on published, citable sources (Martin JC et al., J Appl Biomech 1998 — validation of cycling power model)
- ✓Free forever with no sign-up, account or app install
Frequently asked questions
How does the Cycling Power → Speed Calculator work?+
The cubic term explains cycling's economics: on the flat, doubling speed needs ~8× the aero power, so position (CdA) buys more speed than fitness at race velocities. The calculation uses the formula: P = ½ρ·CdA·v³ + (Crr·m·g + m·g·grade)·v (solved for v). Everything runs instantly in your browser as you type — your inputs are never uploaded.
Is the Cycling Power → Speed Calculator accurate, and what is it based on?+
The method is traceable to authoritative sources: Martin JC et al., J Appl Biomech 1998 — validation of cycling power model. Results are estimates — individual variation always applies, so treat the output as a well-grounded starting point.
Is the Cycling Power → Speed Calculator free and private?+
Yes. It's completely free with no sign-up, and all computation happens locally in your browser, so none of your health data ever leaves your device.
Can I use this for medical decisions?+
This tool is for general fitness information only, not medical or training advice. Consult a professional before changing your routine.
What can I use the Cycling Power → Speed Calculator for?+
It's commonly used for cycling power speed, watts to speed, bike speed calculator. Physics-based speed from watts: air drag, rolling resistance and gradient, with honest defaults.
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