Question: How much does rain — and wearing a rain jacket — affect the aerodynamics of a ride and thereby the speed? Is there a best way to achieve speed in a wet race or fast group ride? — Dave G.
Coach Fred Matheny Replies: In a rainy ride or race, the issue isn’t speed so much as traction.
Rain won’t affect speed by adding rolling resistance unless there are several inches of water on the road. But rain slows you because it’s more dangerous to corner and harder to see when water flies up from the wheels of other riders.
The best way to counteract rain’s effect is to ride in the rain. There’s really no substitute for experience. But many riders won’t train when it’s wet. They lose this opportunity to build their skills. The main reason pros are so good on wet roads is because they have to race on them. They learn by necessity.
And you’ll find that if you ever do a big group ride in the rain, the conditions can actually heighten focus — which is necessary for the group to maintain its speed and cohesiveness.
As for clothing, a floppy rain jacket will cut your speed drastically by acting as a drogue chute. You’ll see pros wearing rain jackets in abysmal conditions, but that’s when the whole pack rides relatively slowly, huddled together for protection. When the crunch comes, the jackets come off no matter how hard it’s raining.