How much time does the wind cost?
Your speed into a headwind and with a tailwind, at the same effort, and what it does to a ride.
Why the wind costs more than it gives back
Air drag grows with the square of the air speed past you. Riding into a 10 mph wind at 14 mph, you push through 24 mph of air; with it at your back at 22 mph, only 12. The headwind half also takes longer, so you spend more of the ride in it. That’s why a windy out-and-back is slower than the same ride on a calm day, even though you get the wind “back” on the way home.
The wind on your real route
Real rides aren’t all headwind or all tailwind. Route Forecast lays the forecast wind over every stretch of your route at the time you’ll ride it and adds up the minutes it costs or gives, and for loops it checks whether the other direction is faster. Open a route.
Questions
How much does a headwind slow you down on a bike?
At the same effort, a 10 mph headwind takes a road rider at 18 mph down to about 13–14 mph, roughly 25–30% slower. A tailwind gives back less than a headwind takes, because air drag rises with the square of the air speed.
Does an out-and-back cancel out the wind?
No. You spend more time in the headwind (you’re slower there) and the drag penalty grows faster than the tailwind help, so a windy out-and-back is always slower than the same ride in still air.
How is the time worked out?
From the power it takes to ride at your speed into that wind (rolling resistance plus air drag for a typical rider and bike), then the speed that same power gives in still air. It’s an estimate: your weight, position and tires change the exact numbers.