Fast delivery and physical exposures- vibration and awkward posture

Status:

completed 02/2026

Aims:

The current popularity of bicycles and pedelecs is evident not only from their sales figures, but also from the road accident statistics. Besides the reported accidents, express delivery riders are exposed daily to numerous other physical hazards that can irreversibly harm their health. These include vibration, noise, UV radiation and unfavourable posture, especially during the lifting and carrying of loads.

As bicycles and pedelecs have only recently been adopted as vehicles for occupational purposes, there is as yet a dearth of evidence from real-case occupational scenarios on how these physical hazards affect workers.

In response to this situation, several projects are to be conducted examining the various hazards (vibration, awkward postures, lifting and carrying of heavy loads, UV radiation and accident risks) to cyclists and pedelec riders in the express delivery sector. This project focused on recording and evaluating exposure to vibration on the handlebar grips (hand-arm vibration) and the surface of the saddle (whole-body vibration). Posture during riding was also analysed, with a particular focus on hand and grip positions.

Activities/Methods:

A preliminary picture of real-case working conditions was to be obtained from 20 field measurements (typically measurements over two hours, representative for a working shift). These measurements covered a range of bicycle types (mountain bike, city bike, racing bike, pedelec), and ergonomic measures such as sprung and vibration-attenuating components and different handlebar grip geometries. Since vibration is transmitted to a rider’s body both through the buttocks and the hand-arm system, exposure was measured by suitable accelerometers attached to the saddle and the two handlebar grips. Posture was recorded by means of motion sensors (CUELA measurement system) attached to the rider’s skin.

A simplified questionnaire (Nordic Questionnaires) was used to record musculoskeletal complaints. The questions concerned complaints and impairments experienced during the preceding twelve months in eight body regions (neck, shoulder, wrist/hands, upper back, lower back/lumbar region, hip/thigh, knee and ankle/feet). The Borg CR10 scale was used to determine and assess the exertion associated with the work. This scale is divided into several sub-segments with different gradings over an overall range from 0 to 10. In addition, a questionnaire was used to record work-related mental strain. The data on the mental stresses was analysed by the BGHW. The measurements were supplemented by documentation of the road surfaces and activities by means of video recordings; small cameras were mounted on the bicycle handlebars and frame for this purpose. Integration of further measurement and analysis methods, extension of the sensor system and inclusion of mental and physiological stress factors considerably increased the overhead for collection and evaluation of the data. In addition, development of a data privacy concept and the required ethics committee approval resulted in unforeseeable additional effort.

Results:

A total of 39 employees of an express delivery service in the four German cities of Berlin, Bonn, Cologne and Stuttgart were included in the study. Owing to the high variability of relevant influencing factors such as road surface conditions, topographical features and personal riding styles, the sample of participants to be monitored by instrumentation technology was expanded, from the 20 originally planned to 31 (4 female, 27 male). A further 8 people were recruited for the questionnaire. Data was collected under real-case working conditions, including a range of weather conditions throughout the year. Varying light conditions were also taken into account by monitoring of both early and late shifts. A total of six conventional bicycles and 25 pedelecs (e-bikes with electric pedal assistance) were studied in routine delivery use. The mean duration of measurement was 107 ± 29 minutes. The mean age of the participants was 37 ± 9 years, the mean body weight 77 ± 16 kg and the mean height 174 ± 7 cm.

The initial results of the vibration measurements reveal elevated stresses in the saddle region and are indicative, in accordance with the provisions of the German Ordinance on noise and vibration protection (LärmVibrationsArbSchV), of relevant exposure to whole-body vibration during the delivery work. The calculated permissible working hours (shift duration) before the action value is reached are 1.0 hours for conventional bicycles and 1.4 hours for pedelecs; the corresponding times before the limit value is reached are 2.6 hours and 3.6 hours respectively. A plausible explanation for the difference in values for a conventional bicycle and a pedelec is the difference in pedalling behaviour and pedelecs’ higher mass: motor assistance reduces the transmission of physical force to the vehicle, whilst the higher total weight of the pedelec can result in greater damping of the vibration transmitted to it. The extent to which pedal assistance influences the vibration introduced into the system is to be studied systematically in a follow-up project.

The exposure to hand-arm vibration marginally exceeds the action value: the action value is reached after 4.8 hours on conventional bicycles and 4.6 hours on pedelecs. The calculated durations of exposure before the limit value is reached are significantly higher, at 22.3 hours and 17.8 hours respectively.

The analyses of the posture show that angles of greater forward body inclination were assumed during riding and that body inclination was associated with greater stresses, particularly in the head, upper body, back and knee joint regions. Similarly, high proportions of non-neutral extensions (i.e. in ergonomically unfavourable hyperextension positions) were observed for the wrists, particularly the left wrist.

The simultaneous effect of vibration and awkward posture poses an elevated health risk. The awkward wrist extensions and back inclinations observed here, together with high levels of vibration exposure during riding, are a critical aspect. Analysis of the consequences of mental strain revealed no unusually high levels of cognitive or emotional irritation in any of the study subjects.

Study of the musculoskeletal complaints shows these to be most common in the lower back, shoulders and neck, persisting in some cases for several days or even weeks. Complaints in the lower back, which comprise 21% of the total, are the most common cause of lost working days, followed by shoulder, knee and hip complaints. Overall, it is clear that the joints and the spine in particular are under significant stress, which poses a major health risk.

The exposure data obtained shows clearly that the high levels of vibration exposure in combination with unfavourable posture constitute a significant health risk and that further research is therefore required. In particular, the stress in the hand-arm region and the lower back indicates that existing prevention approaches are insufficient to effectively reduce cumulative strain. Based upon these findings, a follow-up project is to develop specific measures for ergonomic optimisation, technical relief and organisation of the work, thereby enabling substantiated recommendations to be formulated for sustainable prevention activity.

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