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10:20   Cycling; comfort and feed-back Chair: Johan Molenbroek 10:20 20 mins TEST PROTOCOL FOR IN-SITU BICYCLE WHEEL DYNAMIC COMFORT COMPARISON Julien Lepine, Yvan Champoux, Jean-Marc Drouet Abstract: Bicycle comfort is very important especially for enthusiastic road cyclists who can ride none stop for several hours. Being an abstract concept, several researchers proposed to assess bicycle comfort by measuring the level of vibration transmitted to the cyclist. This can be measured in a controlled laboratory environment but it requires cumbersome and expensive road excitation simulation setup. In situ measurements are an alternative solution but the experiment repeatability is not as good as in the laboratory because many experimental factors are difficult to control while riding a bicycle on the road. For instance: the variation of the cyclist’s position affects the dynamic behaviour of the bicycle/cyclist system, the bicycle velocity affects the level of excitation produced by the road and so on. This paper presents a test protocol to evaluate bicycle comfort with minimal uncertainty inherent of the in-situ experiment. Three main elements are used to enhance measurement repeatability and therefore increase the differentiating capability of the protocol: the measurand selection, the bicycle propulsion and the design of experiment. The power absorbed by the cyclist is used to quantify the level of vibration transmitted to the cyclist because it is far less sensitive to variation of cyclists’ position than to the other measurands used to assess comfort such as acceleration. The bicycle is propelled from an external source which increases precision of the velocity control during the experiment and eliminates measurement noise coming from the bicycle drivetrain. The experiment is specifically designed in term of test runs’ duration and replication to improve its repeatability. The protocol is presented in this paper as a case study of bicycle wheel comfort comparison and can be extended to any components or a complete bicycles comfort comparison. The same case study has been performed with different test methods in laboratory which are used to assess and validate the accuracy of the presented in-situ protocol. 10:40 20 mins PERCEPTUAL THRESHOLDS FOR SHOCK-TYPE EXCITATION OF THE FRONT WHEEL OF A ROAD BICYCLE AT THE CYCLIST’S HANDS Jean-Marc Drouet, Catherine Guastavino, Nicolas Girard Abstract: Road cyclists are typically exposed to two types of road excitations: random-type excitation mainly related to road surface roughness and small irregularities, and shock-type excitation caused by to potholes and cracks in road surface, or even cobblestones like the ones of the Paris-Roubaix race. Shock-type excitation has a more severe and negative effect on the cyclist body than random-type excitation and is the one considered in this work. Shock-type exposure does not only increase the risk of injuries related to the hand-bicycle interface but it can also be a significant source of discomfort, fatigue and disincentive to ride. The ride quality or vibrational comfort of a road bicycle has thus become one of the most regarded characteristics by potential buyers and an important design issue for bicycle manufacturers. Ride quality is closely linked to the cyclist’s perception of road vibration transmitted by his bicycle. To determine the effectiveness of changes made to the bicycle in terms of the reduction of vibration transmitted to the cyclist, we need to measure corresponding changes in mechanical quantities like the transmitted power or the transmitted energy. We also need to assess if the cyclist is able to perceive differences in the level of vibration transmitted to his body. To this end, the objective of this work is to study of perception threshold at the cyclist’s hands for shock-type excitation at the front wheel. Tests described in this paper are carried out using a bicycle treadmill and shock-type excitation level is controlled by varying the size of a wooden stud attached to the surface of the treadmill belt. The rear wheel rests on a support that is slightly upraised from the treadmill surface. Only the front wheel touches the treadmill belt and excitation is therefore applied only to the front part of the bicycle. The perception threshold in terms of transmitted energy and transmitted power at the cyclist’s hands is determined using a two alternative forced choice (2-AFC) discrimination task. Measurement of transmitted energy and power is carried out using instrumented brake hoods. Perception thresholds for 10 cyclists are estimated and discussed in this paper. 11:00 20 mins BENEFITS OF CRANK MOMENT SONIFICATION IN CYCLING Roland Sigrist, Samantha Fox, Robert Riener, Peter Wolf Abstract: Movement sonification, i.e. modulation of sound due to movement, has been shown to be effective to learn complex temporal movement structures [1]. The benefit of movement sonification has been explained by enhanced perception of periodicity, regularity, and speed as well as by facilitated recollection of the movement structure by recalling a sound pattern like a song in the absence of sonification. Furthermore, in many sports, provision of augmented feedback by headphones is more practical than by screens, as the visual sense is already loaded by perceiving the environment [1]. In the present feasibility study, it is evaluated if movement sonification is beneficial to teach a crank moment pattern in cycling using clipless pedals, i.e. a movement with a very high frequency. Six participants (21-27 years) were evaluated. The goal was to learn a reference moment pattern applied to the left crank at 140 W and 80 rpm which required a complex bipedal pushing-pulling action on a cycling ergometer. During training sessions, the experimental group (n=4) heard the sonified reference moment pattern in their right earphone and their own moment of the left crank in their left earphone. Higher frequencies represented higher moments. The goal was to match the frequency from the left earphone to the reference heard in the right using the frequency differential as feedback. After a warm-up, visual instruction of the reference moment pattern, and a baseline test, the participants trained ten sessions of 60 s each. The procedure was repeated on Day 2. Retention and transfer tests (“produce pattern on right leg”) were performed between and at the end of the training sessions as well as on Day 3. The control group (n=2) trained without sonification. Results have shown marginal learning of the movement pattern, whereas group differences were lacking. Certain phases of the movement cycle were improved distinctly by some participants. As stated by the participants, it seems that they focused on certain phases more than on others. Thus, it might be that more training sessions as well as a comparison to another feedback strategy such as visual feedback are necessary to evaluate the impact of movement sonification for pedaling technique training. [1] Sigrist R, Rauter G, Marchal-Crespo L, Riener R, Wolf P (2015). Sonification and haptic feedback in addition to visual feedback enhances complex motor task learning. Experimental Brain Research 233(3): 909-925.