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Peloton drafting even more efficient than we first thought, new study finds

Joe Robinson
13 Jul 2018

Research using a 3D-printed terracotta peloton finds riding at the back can cut aero drag by up to 95%

New research that cycling in a peloton is far more efficient than first thought, with aerodynamic drag at the back dropping to as little as 5% that being experienced at the front.

In a study titled Aerodynamic drag in cycling pelotons: New insights by CFD simulation and wind tunnel testing, researchers at the Eindhoven University of Technology ran wind-tunnel tests on a 3D-printed mini-peloton of 121 terracotta cyclists based on input and feedback from WorldTour riders to establish the most energy-efficient area of the peloton. 

The analysis came to the conclusion that drag in the mid-rear of the peloton is only 5 per cent what a solo rider will experience riding at the same speed. This is considerably lower than previous research, which had the figure at around 70 per cent.

The Dutch university's Professor Bert Blocken, who led the research, worked with professional riders from LottoNL-Jumbo and BMC Racing as well as a wind-tunnel filled with 121 3D-printed terracotta cyclists to gather data, which was then put through supercomputers using ANSYS fluid flow software to establish the most energy-efficient area of a peloton.

Unsurprisingly, the data showed that the mid-rear of a peloton was the most efficient section, with the level of effort required steadily increasing the closer to the front you get. The least efficient part of the peloton, as would be expected, was the very nose with drag reaching 86 per cent of what a solo rider will experience.

Blocken suggested that the misinformation surrounding previous testing was down to the method of testing used.

'Some teams use mathematical cycling models to calculate when exactly a rider should escape to stay out of the grasp of the chasing peloton,' wrote Blocken.

'These models assume that the riders inside the peloton have a resistance of 50 to 70 percent that of an isolated rider.

'These values result from old tests on small groups of up to four in-line drafting cyclists that showed reductions for the third and the fourth cyclist, both up to 50 percent. This has led researchers to believe that also inside a peloton, this 50 percent would apply.'

Blocken then stated that their groundbreaking testing method showed that drag reduced to as little as 5 per cent for isolated riders at the same speed.

Blocken has since spoken out at complaints from pro riders that this data suggests amateurs could comfortably sit in the wheel of a pro. 

Blocken reminded us that this data only applies to a perfect peloton that is riding on a straight and flat road with no external factors such a wind.

What Blocken's findings do however, is increase our appreciation for solo breakaway artists such as Thomas De Gendt (Lotto-Soudal) or Steve Cummings (Dimension Data), who have made a habit throughout their careers of going on long solo breaks resulting in impressive stage victories at the world's best races.

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