Why don’t more people ride a bike to work?
Although there are a number of reasons, the key ones for most people are as follows:
- traffic safety concerns
- degree of effort
- weather issues
- lack of access to a suitable bicycle
- inadequate bike parking and other end-of-trip facilities (including changing rooms, showers, etc.)
People for Bikes:
Bicycling Participation Study: 2020 Survey of U.S. Residents (.pdf) 
Manaugh, K., Boisjoly, G. & El-Geneidy, A. (accepted).
Overcoming barriers to cycling: Understanding frequency of cycling in a University setting and the factors preventing commuters from cycling on a regular basis
“The presence of cycle paths is found to be strongly associated with a higher frequency of cycling commutes. Additionally, an analysis of stated barriers reveals effort and a lack of safety as the most important barriers to potential cyclists. Finally, a qualitative analysis of respondents’ open-ended responses confirms the influence of bicycle paths, but reveals other factors such as the importance of improved interactions among various street users. Findings from this research can be of benefit to transportation engineers and planners who are aiming to increase the use of cycling among various groups of commuters.”
https://tram.mcgill.ca/Research/Publications/over_coming_barriers.pdf
