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

Bert Blocken (Corresponding author), Stefanie Gillmeier, Fabio Malizia, Thijs van Druenen

Research output: Contribution to journalArticleAcademicpeer-review

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.

Original languageEnglish
Article number7
Number of pages11
JournalSports Engineering
Volume24
Issue number1
DOIs
Publication statusPublished - 7 Apr 2021

Bibliographical note

Funding Information:
We thank the technical support team of the Wind Tunnel Laboratory at the Department of the Built Environment at Eindhoven University of Technology: Ing. Jan Diepens, Geert-Jan Maas and Stan van Asten. This work was also sponsored by NWO Exacte en Natuurwetenschappen (Physical Sciences) for the use of supercomputer facilities, with financial support from the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (Netherlands Organization for Scientific Research, NWO). We acknowledge the partnership with Ansys CFD.

Funding Information:
We thank the technical support team of the Wind Tunnel Laboratory at the Department of the Built Environment at Eindhoven University of Technology: Ing. Jan Diepens, Geert-Jan Maas and Stan van Asten. This work was also sponsored by NWO Exacte en Natuurwetenschappen (Physical Sciences) for the use of supercomputer facilities, with financial support from the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (Netherlands Organization for Scientific Research, NWO). We acknowledge the partnership with Ansys CFD.

Publisher Copyright:
© 2021, The Author(s).

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Keywords

  • Aerodynamic cyclist drag
  • Computational fluid dynamics
  • Cycling aerodynamics
  • Motorbike
  • Wind tunnel

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