Tour de France primer: Drafting
Bike racers ride in the slipstream of their competitors to save their strength, so they can hit the wind at exactly the right moment to drop them
Bike racing is a tactical game.
It is not like other endurance sports, where athletes simply try to get to the finish as fast as possible by holding an even pace. That’s because of the effect of drafting.
If you ride behind another rider, so they break the wind for you, you can pedal the same speed as them and save up to half as much effort. The faster you go, the greater this effect is. As your speed increases, you have to push against ever more wind resistance. That is why racers tuck into aerodynamic positions on their bikes and ride one behind the other in single file. Even uphill, at slower speeds, it is a great advantage to pedal behind another rider. Only on the very steepest mountains, does cycling become a race against gravity.
So, bike racing is a matter of picking the right moments to save your strength, while your rivals spend theirs, and then hitting the wind at exactly the right times to leave them behind you.
That’s why bike racers often stick together in a pack for so much of a race. This main group of riders is called a peloton. In a peloton, riders can travel at great speeds much more easily than they could ever do alone.
Who does the work at the front of the pack is an ongoing game. Teammates work with each other and with riders from other teams to shape the situation on the road, so their competitors are pressed into exhausting their strength in the wind.
A group of racers might, for instance, break away and race ahead of the peloton. Even if they are from rival teams, they will share the work at the front of their break by taking turns in the lead. This will put pressure on other teams back in the peloton to chase, while the breakaway riders’ teammates conserve their power in the pack. When they are caught, if they do get caught, those teammates will have a tactical advantage.
However, if the riders in the peloton give up the chase, and it becomes apparent that the breakaway will stay away to the finish line, the reckoning that each rider in front makes will change. Instead of working together, they will find ways to make each other ride in the wind.
If the wind is blowing across the road, for instance, the lead rider might ride on the very edge of the pavement on the downwind side, leaving his competitors no space to benefit from his draft. Or a couple of racers might launch an attack by sprinting ahead on a hill. All of a sudden, it will be in their mutual interest to take even turns in the wind to extend their lead. Their competitors behind will have to decide fast who is going to chase. One of those riders might gamble that his rivals will close the gap for him and stay behind them on their wheels. This is called sitting on.
When the race comes down to a final sprint, drafting also plays a huge role. Hurtling towards the finish line at over 70 km/h, a lead racer has to pedal through enormous amounts of wind resistance to increase his speed. His rivals want to stay on the wheel for as long as possible, and then accelerate around at the last possible moment with a huge burst of power that will carry them over the finish line. Timing that burst right often makes the difference between winning and losing.
The best bike racers aren’t just strong; they are good at playing this game.