Strava KOM Hunting: Why Wind Decides the Seconds
On flat segments, wind is the single biggest factor in your time — bigger than tyre pressure, kit choice or a few grams off the bike. Hunting a Strava KOM mostly means hunting the right weather window.
Aerodynamic drag grows with the square of air speed
At 40 km/h roughly 85 percent of your power goes into moving air. Add 15 km/h of tailwind and the air speed drops to 25 km/h — aerodynamic drag falls to less than half.
That is why KOM times on flat segments almost always come from windy days. The record holder is not the strongest rider on the leaderboard, but the rider who was strong when the wind lined up.
Only the component along the segment counts
What matters is not the wind speed in your weather app but the share of it pointing along your segment. With 20 km/h of wind at 60 degrees to the segment axis, only about 10 km/h acts as tailwind — the rest is crosswind.
- 0 to 30 degrees off: nearly all of the wind helps
- 45 degrees: around 70 percent acts as tailwind
- 90 degrees: pure crosswind, almost no time gain
- over 120 degrees: headwind, postpone the attempt
Twisty segments average the benefit away
A segment with several direction changes extracts far less from the same wind than a straight road. On a loop, tailwind and headwind almost cancel out — and you end up slightly slower, because headwind costs more than tailwind gives back.
For segment selection that means straight, flat, well-aligned stretches are by far the most rewarding KOM targets.
From forecast to decision
Practically you need three things: the bearing of your segment in degrees, an hourly wind forecast with direction, and your existing personal record as a reference. The difference between reference conditions and today's conditions tells you whether a PR is realistic at all.
That is exactly the calculation KomPredict runs for you: segment bearing, hourly forecast and your own history produce a time prediction instead of a gut feeling.
In short
Pick the segment by bearing, the day by wind direction and the hour by forecast — in that order.
Frequently asked questions
How much time does tailwind save on a 2 km segment?
With 10 km/h of effective tailwind on a flat 2 km segment, 10 to 25 seconds is typical depending on your baseline speed. Shorter segments give smaller absolute gains simply because the total time is smaller.
Is a tailwind KOM unfair?
No. Strava leaderboards are not weather-normalised and every rider can choose conditions. Weather planning is part of the discipline.
What wind speed is ideal?
Anything above 15 km/h along the segment is valuable. Above 35 km/h it gets tricky on exposed roads, because gusts break your line and your aerodynamics.