Performances

Performances

  1. PowerCurve performances compared to the circular chain wheel

source: www.noncircularchainring.be

“Why do appropriate non-circular chainrings yield more crankpower …etc.”

Malfait L., Storme G. & Derdeyn M. 2012.

Page 32 & 43. (reference 8)

 

  1. 2. PowerCurve performances compared to other commercially available non-circular chainrings (graphs).

source: www.noncircularchainring.be

“Why do appropriate non-circular chainrings yield more crankpower …etc.”

Malfait L., Storme G. & Derdeyn M. 2012.

page 32 & 43. (reference 8)

2.1 Crank power gain versus a round chainring as a function of pedalling cadence.

2.2 Reduction of peak-power in the extensor muscles of the knee-joint versus round chainring as a function of pedalling cadence.

2.3 Reduction of peak-power in the extensor muscles of the hip-joint versus round chainring as a function of pedalling cadence.

  1. 3. PowerCurve performances compared to other commercially available non-circular chainrings (tables).

source: www.noncircularchainring.be

“Why do appropriate non-circular chainrings yield more crankpower …etc.”

Malfait L., Storme G. & Derdeyn M. 2012.

page 32 & 43. (reference 8)

Conclusion:

The graphs and tables above show undeniably that the PowerCurve chainring is by far the best performing non-circular chain wheel on the market: greatest kinetic crank power gain, greatest reduction of peak load in the knee extensors and being the only oval reducing the peak load in the extensor muscles of the hip.

  1. Experimental confirmation of the theoretical performance figures.

The theoretical crank power gain and the reduction of the peak-loading in knee- and hip joint published in www.noncircularchainring.be (reference 8) have been checked and confirmed by experimental tests.

4.1. Experimental tests crank power gain (reference 17)

In late 2010, comparative tests between the PowerCurve prototype and a conventional round chainring were carried out (with 18 “well trained test subjects”) in the biomechanical laboratory of the department “Kinesiology” at the University of Leuven, Belgium (Prof P. Hespel). Maximal crank power output was measured during a series of short intermittent sprints on a isokinetic (predetermined fixed pedalling rate, moment/torque to maximize) bicycle ergometer. For all pedalling cadences between 40 rpm to 120 rpm (included) the PowerCurve prototype showed crank power gains compared to round. These experimentally measured figures confirm and even surpass slightly the crank power gains calculated with the bio-mechanical model, more specifically in the pedalling frequency range of 80 rpm till 100 rpm, normally used by elite cyclists in competition. This study has not been published yet.

4.2 Experimental tests knee- and hip joint loading (reference 16)

On April 28, 2014 G. Strutzenberger et al., Department of Sport Science and Kinesiology, University of Salzburg, Austria issue a research report: “Effect of chainring ovality on joint power during cycling at different workloads and cadences”.

In this study, the commercially available chainrings, round (Dura Ace Shimano), the Q-Ring oval of Rotor (10% ovality) and the Osymetric (ovality 21.5%) are investigated with 14 elite cyclists. The research results of Grutzenberger et al. fully confirm the theoretical findings of Malfait, Storme & Derdeyn. The load on the knee joint decreases and the load on the hip joint increases with increasing ovality and with increasing cadence. These joint loads are independent of the external power supplied to the pedal.

Very important here is the finding of the increasing load (joint moments/-power) on the hip joint when cycling with non-circular chain wheels in general.

However when cycling with the PowerCurve chainring, the increase is converted into a decrease of the peak-power in the extensor muscles of the hip-joint.

This is accomplished by changing the parameter “crank position relative to the major axis of the oval”. In the “optimal crank position” there is a balance between maximizing the kinetic crank power gain and minimizing the kinetic load of knee- and hip-joint.

4.3 Experimental confirmation of the “zero-results” of the other commercially available non-circular chainrings.

The above mentioned “zero-performances” of the other commercial available non-circular chainrings are confirmed by a myriad of manufacturer-independent scientific studies and testing (see the reference list)

-for Q-Ring

Jones AD 2008 (ref 5)

Peiffer JJ 2010 (ref 11)

Mateo  M 2010 (ref 9)

Diamond ND et al. 2010 (ref 1)

-for Osymetric

Ratel et al. (2004) (ref 14)

Horvais et al (2007) (ref 3)

Rambier N. (2013) (Master Thesis, onder supervisie van prof. Ph.D. Fr Grappe, Université de Franche-Comté, Besançon) (ref 12)

-for Ogival

Grosjean et Grappe (2013) (ref 2)

  1. Referentielijst
  1. DIAMOND, N.D., BATH, B.S., HOLSCHER, R.B., ELMER, S.J., and MARTIN, J.C., Effects of noncircular chainrings on maximal cycling power. Neuromuscular Function Lab, Department of Exercise and Sport Science, College of Health, University of Utah, Salt Lake City, UT, USA, 2010
  2. GROSJEAN, P., et GRAPPE, F., Effets du plateau non circulaire Ogival comparé au plateau circulaire classique sur le pattern de pédalage et lors de différents exercices maximaux et en endurance. Departement Sport-Santé, Université de Franche-Comté, Besançon. 2013
  3. HORVAIS, N., SAMOZINO, P., ZAMEZIATI, K., HAUTIER, C., HINTZY, F., Effects of a non-circular chainring on muscular, mechanical and physiological parameters during cycle ergometer tests Isokinetics and Exercise Science  15, Number 4, 2007.
  4. HULL, M.L. and JORGE, M., A method for biomechanical analysis of bicycle pedalling. Biomechanics 18: 631-644, 1985.
  5. JONES, A.D., and PETERS-FUTRE, E.M., Physiological response to incremental stationary cycling using conventional circular and variable-geared elliptical Q-chain rings. School of Medical Sciences, Faculty of Health Sciences, University of KwaZulu-Natal, 2008.
  6. KAUTZ, S.A. and HULL M.L., A theoretical basis for interpreting the force applied to the pedal in cycling. J. Biomechanics 26, No 2, 155-165, 1993
  7. MALFAIT, L., STORME, G., and DERDEYN, M., Comparative biomechanical study of circular and non-circular chainrings for endurance cycling at constant speedwww.noncircularchainring.be, 2006-2010
  8. MALFAIT, L., STORME, G., and DERDEYN, M., Why do appropriate non-circular chainrings yield more crank power compared to conventional circular systems during isokinetic pedaling?
  9. www.noncircularchainring.be, 2012
  10. MATEO, M., BLASCO-LAFARGA, C., FERNANDEZ-PENA, E., and ZABALA,M., Efectos del sistema de pedalo no circular Q-Ring sobre el rendimiento en el sprint de la disciplina ciclista BMX. European Journal of Human Movement 25, 31-50, 2010. MILLER, N.R., ROSS, D., The design of variable ratio chain drives for bicycles and ergometers-application to a maximum power bicycle drive. Journal of Mechanical Design 102, 711-717, 1980.
  11. PEIFFER, J.J., and ABBISS, C.R., The influence of elliptical chainrings on 10 km cycling time trial performance. International Journal of Sports Physiology and Performance, 2010, 5, 459-468. 
  12. RAMBIER, N. et GRAPPE,F., Effet de l’utilisation du plateau O’symetric sur la performance du cycliste. Departement Sport-Santé, Université de Franche-Comté, Besançon. 2013
  13. RANKIN, J.F., and NEPTUNE, R.R., A theoretical analysis of an optimal chainring shape to maximize crank power during isokinetic pedaling. Journal of biomechanics 41, 1494-1502, 2008.
  14. RATEL, S., DUCHE, P., HAUTIER, C., WILLIAMS, C., and BEDU, M,. Physiological responses during cycling with noncircular “Harmonic” and circular chain rings. Eur J Appl Physiol; 91(1): 100-104, 2004.
  15. REDFIELD, R., and HULL, M.L., On the relation between joint moments and pedalling rates at constant power in bicycling. J. Biomechanics 19: 317-329, 1986.
  16. STRUTZENBERGER, G., WUNSCH, T., KROELL, J., DASTL, J., SCHWAMEDER, H., Effect of chainring ovality on joint power during cycling at different workloads and cadences. Sports Biomechanics, 12 pages, 2014.
  17. VAN HOOVELS, K., KONINCKX, E., and HESPEL, P., Study of the effect of non-circular chainwheels in cycling. Department of Kinesiology, Exercise Physiology Research Group, K.U. Leuven. Unpublished, 2010