This paper describes the design and accuracy evaluation of a dynamometric pedal, which measures the two pedal force components in the plane of the bicycle. To realize a design that could be used during actual off-road cycling, a popular clipless pedal available commercially was modified so that both the form and the function of the original design were maintained. To measure the load components of interest, the pedal spindle was replaced with a spindle fixed to the pedal body and instrumented with eight strain gages connected into two Wheatstone bridge circuits. The new spindle is supported by bearings in the crank arm. Static calibration and a subsequent accuracy check revealed root mean square errors of less than 1 percent full scale (FS) when only the force components of interest were applied. Application of unmeasured load components created an error less than 2 percent FS. The natural frequency with half the weight of a 75 kgf person standing on the pedal was greater than 135 Hz. These performance capabilities make the dynamometer suitable for measuring either pedaling loads due to the rider's muscular action or inertial loads due to surface-induced acceleration. To demonstrate this suitability, sample pedal load data are presented both for steady-state ergometer cycling and coasting over a rough surface while standing.
[1]
Maury L. Hull,et al.
A Compact Portable Data Acquisition Module for Sports Biomechanics Research
,
1990
.
[2]
P D Soden,et al.
Forces applied to a bicycle during normal cycling.
,
1979,
Journal of biomechanics.
[3]
M L Hull,et al.
An improved accuracy six-load component pedal dynamometer for cycling.
,
1996,
Journal of biomechanics.
[4]
M. L. Hull,et al.
Measurement of pedal loading in bicycling
,
1981
.
[5]
M L Hull,et al.
Measurement of pedal loading in bicycling: I. Instrumentation.
,
1981,
Journal of biomechanics.
[6]
Ernest Otto Doebelin,et al.
Measurement Systems Application and Design
,
1966
.
[7]
M. L. Hull,et al.
A Dynamic System Model for Estimating Surface-Induced Frame Loads During Off-Road Cycling
,
1994
.
[8]
M L Hull,et al.
A mechanically decoupled two force component bicycle pedal dynamometer.
,
1988,
Journal of biomechanics.