Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
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©Journal of Sports Science and Medicine ( 2016 ) 15 , 223 - 228

Research article
Effects of a Non-Circular Chainring on Sprint Performance During a Cycle Ergometer Test
Frédérique Hintzy1, , Frédéric Grappe2, Alain Belli3
Author Information
1 Laboratoire Inter-universitaire de Biologie du Mouvement, Université Savoie Mont-Blanc, Le Bourget-du-Lac, France
2 Département Sport-Santé - Equipe Culture Sport-Santé-Société (EA 4660, C3S), Besançon, France
3 Laboratoire Inter-universitaire de Biologie du Mouvement, University of Lyon, St Etienne, France

Frédérique Hintzy
✉ Researcher in Inter-University Laboratory of Human Movement Biology, University Savoy Mont-Blanc, France.
Email: frederique.hintzy@univ-smb.fr
Publish Date
Received: 23-06-2015
Accepted: 01-02-2016
Published (online): 23-05-2016
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ABSTRACT

Non-circular chainrings have been reported to alter the crank angular velocity profile over a pedal revolution so that more time is spent in the effective power phase. The purpose of this study was to determine whether sprint cycling performance could be improved using a non-circular chainring (Osymetric: ellipticity 1.25 and crank lever mounted nearly perpendicular to the major axis), in comparison with a circular chainring. Twenty sprint cyclists performed an 8 s sprint on a cycle ergometer against a 0.5 N/kg-1 friction force in four crossing conditions (non-circular or circular chainring with or without clipless pedal). Instantaneous force, velocity and power were continuously measured during each sprint. Three main characteristic pedal downstrokes were selected: maximal force (in the beginning of the sprint), maximal power (towards the middle), and maximal velocity (at the end of the sprint). Both average and instantaneous force, velocity and power were calculated during the three selected pedal downstrokes. The important finding of this study was that the maximal power output was significantly higher (+ 4.3%, p < 0.05) when using the non-circular chainring independent from the shoe-pedal linkage condition. This improvement is mainly explained by a significantly higher instantaneous external force that occurs during the downstroke. Non-circular chainring can have potential benefits on sprint cycling performance.

Key words: Elliptical chainring, clipless pedal, maximal power output, equipment design, force-velocity test


           Key Points
  • The Osymetric non-circular chainring significantly maximized crank power by 4.3% during sprint cycling, in comparison with a circular chainring.
  • This maximal power output improvement was due to significant higher force developed when the crank was in the effective power phase.
  • This maximal power output improvement was independent from the shoe-pedal linkage condition.
  • Present benefits provided by the non-circular chainring on pedalling kinetics occurred only at high cadences.
 
 
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