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 %, < or = 2.4 %, < 0.8 % and 0.02 N x 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.

Effect of chainring ovality on joint power during cycling at different workloads and cadences

“…To account for this offset, the crank arm was adjusted by an adaptor plate mounted between the chainring fixation points and the chainring. The validity and accuracy of this system has previously been reported (Stapelfeldt et al, 2007).…”

Inverse Dynamics in Cycling Performance

“…Pedal forces were measured using the Powerforce® system and recorded with Simi Motion®. Whereas almost every other device used in cycling analysis is implemented in the pedal the Powertec® system is an own mechanical construction which is mounted between crank and pedal [5]. In contrast to most of the other measuring systems it allows every pedal system to be attached.…”

“…In contrast to most of the other measuring systems it allows every pedal system to be attached. "The instrument is based on two sensor systems which determine the magnetic field variations (Hall-Effect) as a result of the displacement of a small sensor in respect to a magnet" [5]. As soon as a load is applied to the circular construction of the Powerforce® system the corresponding sensor moves in respect to the opponent magnet.…”

Metabolische Leistungsdiagnostik und Trainingssteuerung in der Sportmedizin

“…Leistungsvorgaben aus der Fahrradergometrie sind dagegen nur sinnvoll, wenn im Training ebenfalls eine exakte Leistungsmessung zur Verfügung steht [15,16]. Auch beim Training auf Heimergometern kann die Verwendung der Leistung als Vorgabe sinnvoll sein.…”