Development and Evaluation of a New Bicycle Instrument for Measurements of Pedal Forces and Power Output in Cycling

Abstract

Determination of pedal forces is a prerequisite to analyse cycling performance capability from a biomechanical point of view. Comparing existing pedal force measurement systems, there are methodological or practical limitations regarding the requirements of scientific sports performance research and enhancement. Therefore, the aim of this study was to develop and to validate a new bicycle instrument that enables pedal forces as well as power output measurements with a free choice of pedal system. The instrument (Powertec®-System) is based on force transducer devices, using the Hall-Effect and being mounted between the crank and the pedal. Validation of the method was evaluated by determining the accuracy, the cross talk effect, the influence of lateral forces, the reproducibility and, finally, a possible drift under static conditions. Dynamic tests were conducted to validate the power output measurement in reference to the SRM-System. The mean error of the present system was - 0.87 ± 4.09 % and - 1.86 ± 6.61 % for, respectively, the tangential and radial direction. Cross talk, lateral force influence, reproducibility and drift mean values were < ± 7 %, ≤ 2.4 %, < 0.8 % and 0.02 N · min^-1, respectively. In dynamic conditions, the power output measurement error could be kept below 2.35 %. In conclusion, this method offers the possibility for both valid pedal forces and power output measurements. Moreover, the instrument allows measurements with every pedal system. This method has an interesting potential for biomechanical analyses in cycling research and performance enhancement.

Key words

Cycling - pedal forces - workload - ergometer

References

• 1 Alvarez G, Vinyolas J. A new bicycle pedal design for on-road measurements of cycling forces.  J Appl Biomech. 1996;  12 130-142
• 2 Bland J M, Altman D G. Statistical methods for assessing agreement between two methods of clinical measurement.  Lancet. 1986;  1 307-310
• 3 Boyd T, Hull M L, Wootten D. An improved accuracy six-load component pedal dynamometer for cycling.  J Biomech. 1996;  29 1105-1110
• 4 Broker J P, Gregor R J. A dual piezoelectric element force pedal for kinetic-analysis of cycling.  Int J Sports Biomech. 1990;  6 394-403
• 5 Brooke J D, Hoare J, Rosenrot P, Triggs R. Computerized system for measurement of force exerted within each pedal revolution during cycling.  Physiol Behav. 1981;  26 139-143
• 6 Ericson M O, Ekholm J, Svensson O, Nisell R. The forces of ankle joint structures during ergometer cycling.  Foot Ankle. 1985;  6 135-142
• 7 Gardner A S, Stephens S, Martin D T, Lawton E, Lee H, Jenkins D. Accuracy of SRM and power tap power monitoring systems for bicycling.  Med Sci Sports Exerc. 2004;  36 1252-1258
• 8 Gregor R J. Biomechanics of cycling. Garret WE, Kirkendall DT Exercise and Sport Science. Philadelphia; Lippincott Williams 2000: 515-537
• 9 Gregor R J, Cavanagh P R, Lafortune M. Knee flexor moments during propulsion in cycling - a creative solution to lombard's paradox.  J Biomech. 1985;  18 307-316
• 10 Hoes M J, Binkhorst R A, Smeekes-Kuyl A E, Vissers A C. Measurement of forces exerted on pedal and crank during work on a bicycle ergometer at different loads.  Int Z Angew Physiol. 1968;  26 33-42
• 11 Hull M L, Davis R R. Measurement of pedal loading in bicycling: 1. Instrumentation.  J Biomech. 1981;  14 843-856
• 12 Jones S M, Passfield L. The dynamic calibration of bicycle power measuring cranks. Haake SJ The Engineering of Sport. Oxford; Balkema Publishers 1998: 265-274
• 13 Künstlinger U, Ludwig H G, Stegemann J. Force kinetics and oxygen consumtion during bicycle ergometer work in racing cyclists and reference-group.  Int J Sports Med. 1984;  5 118-119
• 14 Millet G P, Tronche C, Fuster N, Bentley D J, Candau R. Validity and reliability of the Polar S710 mobile cycling powermeter.  Int J Sports Med. 2003;  24 156-161
• 15 Mornieux G, Zameziati K, Mutter E, Bonnefoy R, Belli A. A cycle ergometer mounted on a standard force platform for three-dimensional pedal forces measurement during cycling.  J Biomech. 2006;  36 1296-1303
• 16 Newmiller J, Hull M L, Zajac F E. A mechanically decoupled two force component bicycle pedal dynamometer.  J Biomech. 1988;  21 375-386
• 17 Patterson R P, Pearson J L, Fisher S V. The influence of flywheel weight and pedalling frequency on the biomechanics and physiological responses to bicycle exercise.  Ergonomics. 1983;  26 659-668
• 18 Reiser R F, Peterson M L, Broker J P. Instrumented bicycle pedals for dynamic measurement of propulsive cycling loads.  Sports Engineering. 2003;  6 41-48
• 19 Rowe T, Hull M L, Wang E L. A pedal dynamometer for off-road bicycling.  J Biomech Eng. 1998;  120 160-164
• 20 Sanderson D J, Black A. The effect of prolonged cycling on pedal forces.  J Sports Sciences. 2003;  21 191-199
• 21 Sanderson D J, Henning E, Black A. The influence of cadence and power output on force application and in-shoe pressure distribution during cycling by competitive and recreational cyclists.  J Sport Sci. 2000;  18 173-181
• 22 Sargeant A J, Davies C T. Forces applied to cranks of a bicycle ergometer during one- and two-leg cycling.  J Appl Physiol. 1977;  42 514-518
• 23 Soden P D, Adeyefa B A. Forces applied to a bicycle during normal cycling.  J Biomech. 1979;  12 527-541
• 24 Stone C, Hull M L. Rider bicycle interaction loads during standing treadmill cycling.  J Appl Biomech. 1993;  9 202-218
• 25 Too D. Biomechanics of cycling and factors affecting performance.  Sports Med. 1990;  10 286-302
• 26 Wheeler J B, Gregor R J, Broker J P. A dual piezoelectric bicycle pedal with multiple shoe pedal interface compatibility.  Int J Sports Biomech. 1992;  8 251-258