The effect of vibrational exposure to sports activities has shown to have a negative influence on the performance of sportsmen. This superimposed vibration cannot be neglected during cycling, especially when cycling a cobblestones pavement. Because human comfort to vibrations is rather subjective, two methods exist to evaluate and quantify the vibrational comfort. The aim of this study is to set up an experimental test procedure for quantifying vibrational comfort and to find out which method is most appropriate for measuring comfort during cycling. Vibrational comfort and bicycle instrumentation: The first evaluation method is written down in whole-body and hand-arm vibration standards (BS6841:1987), at which the acceleration level measured at the contact points between the cyclist and the bicycle is used for vibrational comfort evaluation. The second method is called `absorbed power`, which is a measure for the power lost by the human body due to vibrational exposure. Absorbed power is defined in terms of contact velocity and contact force at the contact points between the cyclist and the bicycle. The racing bicycle used for testing is equipped with acceleration and force sensors, each measuring the contact acceleration and contact force at the handlebar and the saddle in two orthogonal directions in plane of the bicycle. The contact velocity then results from integrating the acceleration signal. The entire data acquisition and storage system is packed in a backpack which is carried by the cyclist. Results: The outdoor tests were performed with a Museeuw Flax 5 racing bicycle and a cycling speed of 30km/h is maintained over a 180m distance at both an asphalted and cobblestones pavement road (Mortier, 2011). The results were analysed using both evaluation methods and both show less comfort when cycling on cobblestones. If the cyclist is asked to handle the bicycle in such a way that his vibrational exposure decreases subjectively, this subjective feeling of increased comfort is also found in the results from the absorbed power method whereas the whole-body vibration method yields contrary findings. Another advantage of the absorbed power method is that power lossis expressed in Watt, which may be related to cycling performance. These initial tests have shown that the bicycle instrumentation is successful and future work can lead to conclusions on how comfort is related to e.g. tyre pressure, bicycle frame material, cycling position, etc.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Veröffentlicht von Vrije Universiteit Brussel. Alle Rechte vorbehalten.