Drafting the Peloton

Peloton in CyclingI’m sure you have seen the pictures and videos of cycling races, either in the Olympics or the Tour de France. Packs of riders all clumped together, appearing to pedal almost in unison, winding their way around curves or rushing down straight-aways. I could never quite understand why, if the goal is to be first to cross the finish line, a rider would stay with the pack. It would be more difficult to break out at the last minute to win the race.

However, after reporting the story for North Carolina Science Now about the A2 Wind Tunnel in Mooresville, now I understand the strategy. It’s all about the wind.

It’s not clear just when the strategy started. The earliest organized sport of road bicycle racing dates to around 1868. The first world championship was held in 1893. The sport of cycling has been part of the Olympic Games since the modern sequence started in Athens in 1896.

Somebody, somewhere during that period realized it’s much easier, and requires a lot less energy, if you follow behind a rider rather than lead the pack. It’s all about taking advantage of the aerodynamic benefit of drafting, where a rider is still peddling, but riding very closely in the slipstream of the rider in front. The rider in front of the pack is cutting through the wind, fighting the maximum amount of drag. The rider following closely behind doesn’t have to do that. Studies have shown that riding in the pack, what’s called the peloton, can save almost 40% of the energy needed to pedal a bike. 

If you want a good example of drafting, just watch a NASCAR race. The drivers do it all the time to save gas.

The strategy, of course, is to force the leader to do more of the work and possibly tire early and fall back. The rider drafting has then saved enough energy for a last minute burst of speed to break out of the pack. The challenge is to not get so boxed in that a rider can’t break out. But that’s another matter.

The idea of drafting also explains the huge pileups in major races that make the news highlights.

Dynamics of CyclingTo successfully draft, riders must stay very close to the cyclist in front. It’s not unusual for professional cyclists to be within inches of the bicycle in front. The shorter the distance is between the bicycles the larger the decrease in wind resistance. However, riders are often so close, that there is almost no time to swerve out of the way in the event of a crash.

Drafting can also work into a race strategy. Teams of riders can strategize and pick a leader, and they can assign the rest of the team to keep that person out of the wind and in a good position, until the leader needs to make a move and break out of the pack.

The next time I go bike riding with my family, I’ll explain all of this to them. I’ll tell them how it would make it easier for Dad if I can follow behind and use less energy.

I’m don’t think they’ll agree to the plan. But it’s worth a try!

- Frank Graff

Frank Graff is a producer/reporter with UNC-TV, focusing on North Carolina Science Now, a weekly science series that airs Wednesdays as part of North Carolina Now on UNC-TV. In addition to producing these special segments, Frank will provide additional information related to his stories through this North Carolina Science Now Reporter's Blog!


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