This thesis is a case study of a Polish city which faces a problem of high automobile share and little popularity of cycling in its residents’ modal split. In times when the world is facing climate change and there is a need of preserving scarce resources, it is essential that urban areas adopt a sustainability approach to the way they develop. Thus, this research focuses on what attitude is held by residents and local authorities of the subject city and how it should be facilitated so that biking for transportation becomes more common. With the approach of Ajzen’s (1991) theory of planned behaviour, the citizens’ perspective is investigated by a questionnaire where the results lead to dividing the population sample into seven groups based on their attitude. Such segmentation into population groups with respect to mobility can help promote sustainable mobility behaviour and is essential in order to address the problem successfully. Local authorities’ attitude is examined by interviews and secondary data analysis. A principal finding here is that in this city bicycle is a secondary or tertiary mode of transportation, while there is a prevailing automobile priority continuously being facilitated by the authorities. The problem lies in that it is not fully understood how bicycling can bring benefits to the city and that managing transportation is an essential part of sustainable urban development. The dissertation concludes with suggestions for both the residents and the authorities so that pro-sustainability behaviour can occur. Additionally, the analysis in this paper could be used in a number of similar cities in Poland.