Ergonomic Impact of Backpacks on Bicycle Couriers

Abstract

Online supermarkets have experienced rapid growth, especially during the COVID-19 pandemic. According to one forecast, the global online food delivery market will generate annual sales of US $1.38 trillion by 2025. The penetration rate in the meal delivery market is expected to be 28.2% in 2025, resulting in steady growth in the bicycle courier profession. Experiments are to be conducted to determine how the load carried is distributed on the back, how the load affects pressure on the buttocks, and how much of the load is absorbed by the shoulders.The measurements were carried out using an ergometer 8008 TRS 3 from the manufacturer Daum Electronic. The wattage range can be changed in 5-watt increments, which meets the requirements of the tests. The backpacks used for the tests are from the companies Flink and Mjam. Pressure sensors from Tekscan are used to measure the forces acting on the back and buttocks.Pressure and force measurements were used to show the forces acting on a cyclist’s body when carrying additional weight. As expected, a slight difference in the measured force between an upright and a forward-leaning sitting position (as on a racing bike) exists, explaining that a forward-leaning posture means that less force has to be borne by the straps and thus by the back. It was possible to show how the pressure is distributed across the cyclist’s back and buttocks and how great this pressure is. Backpacks from two delivery services were compared. It was found that with a load of 15 kg, the maximum pressure on the back caused by the Mjam backpack was higher overall giving a maximum value of 10 kPa, but was more evenly distributed than the pressure caused by the Flink backpack which gave a maximum value of 9.2 kPa. The Flink model showed that the maximum load carried by the back was 184.2 N, greater than that of Mjam, which was 166.5 N. By testing two different saddles, it was possible to show how pressure is distributed between them. The racing saddle showed pressure peaks up to 59.1 kPa on the sit bones. In contrast, the softer and wider touring saddle showed a more even pressure distribution across the sit bones and perineum, with pressure peaks reaching 50.7 kPa. As expected, measurements of the forces in the shoulder straps of the backpacks showed a decrease with a less upright posture, thus shifting the weight to the back. These results also corresponded with those from the pressure measurement on the back.Several series of measurements should be carried out in the future, with more test subjects to improve the results further. To assess the physiological strain on bicycle couriers more accurately, forces exerted on the handlebars have to be also measured. A relief device explicitly developed for this application has significantly reduced the forces exerted. Nevertheless, the ergonomics of bicycle courier backpacks need to be improved considerably, for example, through more comfortable padding. Comparisons with padding used in mountaineering backpacks showed a significant reduction in maximum forces and pressure exerted on the back of the users.