# Study on the Minimum Operation Width of Human-Powered Bicycles for Safe and Comfortable Cycling
## 5 Conclusions and Discussion
### Limitation and Future Work  
This study aims to establish the minimum operational width for human-powered bicycles, particularly at higher speeds, thereby contributing to the theoretical framework employed for designing exclusive bicycle paths in China. These bikeways are completely segregated from motorized traffic and are dedicated solely to fully human-powered bicycles, ensuring safety, higher speed, and efficiency. Our focus is limited to human-powered bicycles operating in single-file, yet the insights gained can serve as a starting point for future bikeway design.  
Building upon our findings as the baseline, future research should extend to determine the optimal widths for bikeways, as illustrated in Figure 15. The overall width of bikeways can be calculated by multiplying the number of lanes--determined by bicycle traffic volume and lane capacity--by the basic lane width, assuming edge conditions remain consistent. For example, investigating two-way cycling for human-powered bicycles would aid in determining the minimum operational widths necessary to accommodate the evading effect effectively [65]. Additionally, we should consider supplementary width requirements for non-motorized lanes, which may require more space due to features such as elevated curbs, barriers, and vegetation (A and C in Figure 15). Accommodating various bicycle types, including e-bikes with different dimensions and speeds, as well as interactions with moving or parked motorized vehicles (D in Figure 15), is also essential, especially in areas with speed differentials. Lastly, as the network of bikeways expands, factors like intersections, gradients, and sharp curves may necessitate additional width beyond the baseline measurements established in this study.  
**Author Contributions:** Conceptualization, J.H. and S.Q.; methodology, S.Q. and R.W.; software, S.Q., S.M. and Z.Z.; validation, J.H. and R.W.; formal analysis, S.Q.; investigation, S.Q., Y.G. and Z.Z.; resources, J.H., Y.G. and S.M.; data curation, R.W. and Y.G.; writing--original draft preparation, S.Q.; writing--review and editing, J.H., R.W., Y.G., S.M. and Z.Z.; visualization, S.Q.; supervision, J.H. and R.W.; project administration, J.H.; funding acquisition, J.H. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded in part by the 'Urban Carbon Neutrality' and 'Urban Renewal' Science and Technology Innovation Fund Project at Beijing University of Technology.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.  
**Data Availability Statement:** The data presented in this study may be available from the first author upon reasonable request.  
**Acknowledgments:** We acknowledge all the tested cyclists for their participation. We would like to express our sincere gratitude to [PERSON] from Delft University of Technology for generously sharing his experimental apparatus' detail and valuable insights.  
**Conflicts of Interest:** The authors declare no conflicts of interest.  
Figure 15: Illustration for future work.