If you have ever watched the Tour de France or any professional cycling race, you have probably seen the riders lining up in single file and riding very close behind one another. This is called drafting and is an important technique that cyclists use to reduce energy output and increase speed on long races.
However, it’s a technique that is not only important for racers. Touring cyclists or anyone else who rides long distances in potentially windy areas should know how to draft; it can be the difference between a great afternoon ride and a hellish time fighting against the wind.
How Drafting Works
As a bicycle rider moves forward along the road or trail, the air in front is pushed out toward the sides and then behind the rider. Like a large truck or car barreling down the road, the human body can move a substantial amount of air. As this air is pushed out of the way, it creates a low-pressure zone behind the cyclist. This low-pressure zone causes air to rush in from the back and sides, in what physicists would call a vortex. This vortex acts like a wind: if you are close enough behind a bicycle rider (or car) that is on the move, you will feel these vortexes actually contribute to your speed, pulling you along behind the lead cyclist.
Professional cyclists take advantage of this effect on long rides by riding behind each other in a narrow line. This allows each rider to draft off the rider in front of him or her, excepting the rider in front, who is cutting through the wind for everyone else. Proper drafting can reduce the amount of energy needed from the riders behind them by a very substantial amount, as much as 30, 40, or even 50 percent.
It is important to note that drafting is most effective at high speeds or when there is substantial wind. Drafting can also help keep you a bit warmer on cold days when the wind seems to cut right through your clothing.
Drafting is a skill that is really straightforward to learn. The key components of drafting are proper position, proper distance, riding style and safety. We will go over them here one by one.
Finding the proper position while drafting is usually pretty straightforward. If there is no wind, this is the position you want to be in: Your front wheel should be several inches behind and to one side (usually the left) of the rear wheel of the rider behind you.
It is common while drafting for the puller (the leader) to rotate to the rear of the pack every so often. This allows a rest, while successive riders take the lead, each taking a turn at performing the most difficult task.
Proper distance is critical. Most people who try drafting for the first time ride too far back, which leaves them out of the slipstream of the rider in front of them, having to break the wind all over again for themselves. Unless you are following a rider who is substantially bigger than yourself, you will need to stay quite close to their rear wheel — close enough that, at first, it will feel slightly dangerous. While you ride, work to maintain this spacing. It will feel awkward initially, but over time your skills will improve and you will begin to reap the full benefits of drafting.
It is extremely important to use the right riding style; to do otherwise can be dangerous. The leader should maintain a constant speed; it can be very dangerous if the puller varies speeds, as they can cause a crash in the blink of an eye. The leader should also avoid swerving or changing directions rapidly. All movements and maneuvers should be slow, steady and controlled to give the riders behind a chance to react.
Staying safe while drafting is very important. As the riders are all bunched up together, one person crashing can quickly multiply and cause a much larger pileup. Each rider should take it upon himself to keep his eyes out for debris or obstacles on the road, and to watch the riders in front with an eagle eye in case anything happens or they have to brake quickly.
If an obstacle does approach, or it is necessary to slow down or make maneuvers, use your voice to alert other riders. Give a loud shout to let everyone know what is coming up.
There is one situation which requires a modification of the normal drafting style. This occurs when wind from the front is combined with wind from the side — called a side wind or a crosswind. In this situation, lining up in a straight line can be detrimental. The side wind will reduce efficiency and could cause accidents. To deal with this, riders have developed something called the echelon formation.
To use the echelon formation, the front rider should be trailed at an angle opposite the direction that the side wind is coming. For example, if the side wind is coming from 45 degrees to the left of the lead rider, those drafting should stagger themselves behind and to the right. This will give maximum protection from both headwinds and crosswinds.