Drafting in Triathlon

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

During a triathlon you can gain a significant advantage by swimming, 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.

Swim Drafting

Research shows that swimming 50 cm behind another athlete reduces your drag coefficient by 21% whereas swimming to the side of another athlete can reduce your drag by around 7%. In an Olympic or IRONMAN 70.3 (Half Distance) Triathlon, this could save you up to two minutes.

What’s the best way to do this? In an ideal world, you should aim to swim behind someone slightly faster than you. To do this, you may have to start a little nearer the front than you might usually, and then swim hard for the first couple of minutes.

If you’re not comfortable with that idea, you can still benefit by swimming with people who are of similar ability to you. In this situation, you might feel like you’re going too slow, and you’ll be tempted to overtake. Whereas in actual fact, you’ll be swimming at a good pace, it just feels easier because you’re drafting.

A word of caution: don’t follow other swimmers blindly. Make sure the person you’re following is heading in the right direction and not weaving all over the place. Be prepared to find another pair of feet if you need to.

Also, try not to infuriate anyone by touching their toes. Nobody will be cross about you drafting behind them if they hardly know you’re there. It’s up to them to swim behind another athlete if they want to; you should concentrate on your own race. Just try and be respectful.

Bike Drafting

Most (not all) amateur triathlon events are non-drafting. Meaning you’re not allowed to ride directly behind the rider in front of you. At IRONMAN events, for instance, the legal drafting distance is currently 12 meters. This is measured from the front of the bike in front, to the front of yours.

Riding at this 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 run.

Don’t feel bad about it either. With up to 2000 cyclists all on the same route, there’s literally not enough room on the road for everyone to leave a massive gap. So make sure you abide by the race rules and, if anything, leave 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 per cent 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 swim and bike sections. Still, every second counts when you’re chasing a time.

This article was based on our blog post: Legal Triathlon Drafting Tips

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