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Impact of a motorcycle on cyclist aerodynamic drag in parallel and staggered arrangements

Authors
  • Blocken, Bert1, 2
  • Gillmeier, Stefanie1
  • Malizia, Fabio1, 2
  • van Druenen, Thijs1
  • 1 Eindhoven University of Technology, Eindhoven, 5600 MB, the Netherlands , Eindhoven (Netherlands)
  • 2 KU Leuven, Kasteelpark Arenberg 40 - bus 2447, Leuven, 3001, Belgium , Leuven (Belgium)
Type
Published Article
Journal
Sports Engineering
Publisher
Springer London
Publication Date
Apr 07, 2021
Volume
24
Issue
1
Identifiers
DOI: 10.1007/s12283-021-00344-3
Source
Springer Nature
Keywords
License
Green

Abstract

Cycling races contain a multitude of motorcycles for various activities including television broadcasting. During parts of the race, these motorcycles can ride in close proximity of cyclists. Earlier studies focused on the impact of a nearby motorcycle on cyclist drag for in-line arrangements. It was shown that not only a motorcycle in front of a cyclist but also a motorcycle closely behind a cyclist can substantially reduce cyclist drag. However, there appears to be no information in the scientific literature about the impact of the motorcycle on cyclist drag for parallel and staggered arrangements. This paper presents wind tunnel measurements of cyclist drag for 32 different parallel and staggered cyclist-motorcycle arrangements. It is shown that the parallel arrangement leads to a drag increase for the cyclist, in the range of 5 to about 10% for a lateral distance of 2 to 1 m. The staggered arrangement can lead to either a drag increase or a drag decrease, where the latter is about 2% for most positions analyzed. For one of the parallel arrangements, computational fluid dynamics simulations were performed to provide insight into the reasons for the drag increase. A cyclist power model was used to convert the drag changes into potential time gains or losses. Compared to a lone cyclist riding at a speed of 46.8 km/h (13 m/s) on level road in calm weather, the time loss by a drag increase of 10%, 4% and − 2% was 2.16, 0.76 s and − 0.80 s per km, respectively. These time differences are large enough to influence the outcome of cycling races.

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