Every cyclist knows headwinds are brutal — but why doesn't the tailwind on the way home cancel it out? This interactive tool shows exactly why an out-and-back ride in wind is always slower than the same ride in calm conditions, using real physics and realistic power numbers.
Aerodynamic drag scales with the square of your speed through the air. A headwind increases your air speed far more than a tailwind decreases it — so the extra drag into wind massively outweighs the drag reduction going home.
Worse still, because you're slower into the headwind, you spend far more time in the hard section. On a 40 km ride with 20 km/h wind, you spend 68% of your time fighting the headwind and only 32% enjoying the tailwind.
The headwind leg produces 1.6× the drag force of calm conditions, while the tailwind only drops it to 0.65×. The maths never balances — this is Jensen's inequality in action.
| Wind | Headwind speed | Tailwind speed | Avg speed | Time penalty |
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