Drafting in Duathlon

How to use the drafting rules to bike and run several minutes faster...

During a duathlon, you can gain a significant advantage by riding and running behind other athletes legally and respectfully. It’s known as drafting, and it's free speed waiting to be had, so don’t leave it on the table. Here we’ll explain how to get it right.

Bike Drafting

Most (not all) amateur duathlon events are non-drafting. Meaning you’re not allowed to ride directly behind the rider in front of you. The legal drafting distance is 10 or 12 meters (depending on the length of your race). This is measured from the front of the bike in front to the front of yours.

Riding at a 12m legal distance reduces your drag coefficient by around 9% compared to riding solo. That can mean a saving of around 25 watts, depending on conditions. Put another way; you’ll pedal approximately 10% less hard for a given speed. There are lots of variables to consider, but the point is that legal drafting can help you knock minutes off your bike splits. Or enable you to conserve more energy for the final run.

Don’t feel bad about it either. Just make sure you abide by the race rules and if anything leaving a slightly bigger gap than necessary. The pace will ebb and flow, so you’ll need to concentrate on maintaining a legal distance throughout. Just be considerate to other athletes and be prepared to ride on your own or at the front when needed.

Run Drafting

There is a small benefit to drafting when running. The faster your run or the greater the headwind you’re running into, the more benefit you’ll experience. At a relatively fast running speed of 5:28 min/miles or 3:23 min/k, it has been shown to be two percent easier to run directly behind another runner. This benefit shrinks exponentially, the slower you run. And the benefit grows again, the stronger the headwind you’re running into.

So there is potential to save energy for a given pace or run faster for a given amount of energy. But not as much as there is for the bike section. Still, every second counts, when you’re chasing a time.