A tightly packed bunch of road racing cyclists in plain jerseys sweeping along a country road between green fields
AI-generated image, not a photograph of a real person or place.
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WHAT THE WIND TUNNEL SHOWS

Hide from
the wind.

5–7% DRAG deep in the bunch

  • Drag grows with speed squared
  • Shelter beats strength
  • Even a bike behind helps
  • The physics behind the bunch

At racing speed, the air pushes back hard.

Drag grows with the square of speed, so going faster gets hard quickly. Racers beat it by tucking in behind others. Wind tunnel tests and huge computer simulations show the shelter is far bigger than riders once assumed.

Updated

Find the shelter

THE SHORT ANSWER

Ride in the bunch,
pay a fraction.

Air resistance climbs steeply with speed.
Riding in someone's wake cuts it dramatically.

PELOTON

Almost out of the wind

In a study of a 121-rider peloton, riders in the middle and at the back faced about 5 to 7% of the drag of a solo rider, like riding at 12 to 15 km/h in a bunch doing 54 km/h.

Find the shelter

THE PHYSICS

Speed squared

NASA explains that drag depends on air density, body size and shape, and the square of the velocity. Double the speed and the drag force rises about fourfold.

See the numbers

MOTORBIKES

Help from behind, too

Wind tunnel tests found a motorbike 0.25 m behind a time-trial rider can cut their air resistance by almost 9%, and three motorbikes by up to 14%.

Where the wind goes

A QUICK SHELTER CHECK

Where is
the rider?

Pick a position to see how much air resistance a racing cyclist saves, from Eindhoven University of Technology wind tunnel and simulation studies. The bar shows how much shelter the rider gets.

Shelter check

Choose a position
Riding aloneFull drag

The baseline: the rider pushes all of the air aside alone. Every other figure here is compared with this.

30 m behind a race motorbike12% less drag

Even at 30 metres the wake still helps, worth about 2.6 seconds a minute at 54 km/h. At 50 metres a 7% reduction is still measurable.

10 m behind a race motorbike23% less drag

At 10 metres the drag falls by about a quarter, a time gain of about 5.3 seconds every minute.

2.6 m behind a race motorbike48% less drag

Nearly half the drag disappears: a rider who could do 54 km/h alone could ride at about 67 km/h, gaining 14.1 seconds a minute.

Middle or back of a big peloton5–7% of solo drag

Shielded by many rows of riders, cyclists face only a small fraction of solo drag. Earlier estimates from small groups were 50 to 70%.

Sources: Eindhoven University of Technology news on peloton drag (2018) and on following motorbikes (2016, 2019).

Figures from studies at a reference speed of 54 km/h. Real races vary with wind, road and the gaps between riders.

TWO NUMBERS WORTH KNOWING

Bigger shelter
than anyone thought.

One figure from the biggest peloton simulation,
one from the motorbike tests.

5–7%

Drag in the middle or back vs solo

Simulations with 3 billion cells and wind tunnel tests of a complete 121-rider model peloton gave the same answer: far less drag than the 50 to 70% previously assumed.

PELOTON · TU EINDHOVEN 2018

48%

Drag cut 2.6 m behind a motorbike

At about 2.6 metres behind a motorbike, a rider experiences up to 48% less drag, gaining 14.1 seconds every minute at a reference speed of 54 km/h.

MOTORBIKE · TU EINDHOVEN 2019

The researchers suggested race teams' models for timing breakaways had used the older, smaller drag savings, which may help explain why so few breakaways succeed.

READING A RACE

Where the
shelter is.

Scale models of a cyclist and a motorbike lined up in a wind tunnel test section with smoke streaming past them
AI-generated image, not a photograph of a real person or place.

The studies also point to where riders choose to sit, and why the rules on race vehicles matter.

  1. Breakaways lose the shelter

    A rider who escapes faces far more drag than the bunch. The researchers said this may explain why so few escapes succeed.

  2. Rows 6 to 8 for contenders

    The peloton study's lead researcher suggested rows 6, 7 or 8 for sprinters and overall contenders: well sheltered, but close enough to react.

  3. The very back has a cost

    Drag is very low at the back, but there is less chance to react to attacks and crashes happen more often.

  4. Watch the motorbikes

    Researchers urged cycling's governing body to raise the 10 m minimum gap for following motorbikes to 30 m, and to enforce it.

MEASURED TWO WAYS

Simulation and
wind tunnel agree.

A lone cyclist in a low, tucked time-trial position riding along an empty road in the early morning
AI-generated image, not a photograph of a real person or place.

The peloton study combined computer simulations of two 121-rider pelotons with slightly different gaps between rows, and wind tunnel tests on a complete peloton of scale models. The two methods independently gave the same results.

The motorbike studies used the same pairing. In short time trials a following motorbike could be worth a few seconds; in longer time trials the researchers said the difference could reach a minute.

Questions

Questions people ask

Why do racing cyclists ride in a bunch?

To shelter from air resistance. An Eindhoven study found riders in the middle and back of a 121-rider peloton experience only about 5 to 7% of the drag of a solo rider.

How much does drafting help?

Earlier studies of small groups riding in line found drag fell to about 50 to 70% of a lone rider's. Deep inside a large, tightly packed peloton the saving is much larger.

Why does speed make cycling so much harder?

Drag depends on the square of velocity, NASA explains. Doubling speed roughly quadruples the drag force a rider must overcome.

Can a vehicle behind a rider really help?

Yes. Wind tunnel and simulation studies found a motorbike 0.25 m behind a time-trial rider cut drag by almost 9%, and up to 14% with three motorbikes.

How close can race motorbikes ride?

The researchers noted a regulatory 10 m distance and called for it to be raised to 30 m and properly enforced, as the wake still reduces drag by about 12% at 30 m.

Sources

Where the facts come from

  1. TU Eindhoven (Cursor): A cyclist in a peloton experiences considerably less air resistance than assumed (2018)
  2. TU Eindhoven research portal: Aerodynamic drag in cycling pelotons, new insights by CFD simulation and wind tunnel testing
  3. TU Eindhoven: Time gain for cyclist behind motorcycle much bigger than expected (2019)
  4. TU Eindhoven (Cursor): Racing cyclist benefits from motorcycle right behind him (2016)
  5. NASA Glenn Research Center: The drag equation

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