In this diploma thesis I focus on the formation of urban cycling including heterogeneous participating actors - people, discourses, technologies, infrastructures and other materialities. I examine cyclists' relationships with their environment and describe asymmetries connected with the dominant status of automobilism in urban environment, and strategies for contesting this situation. I also focus on cyclo-activist discourse which plays an important role in the empowerment of cyclists in urban traffic. Mobilizing arguments of critical theory and the "right for the city" concept cyclo-advoacy strives to include as many citizens as possible in debate about public space and in this way support pro-cycling developments. From the perspective of actor-network theory (ANT) this strategy has limits due to its operation with stabilized social science categories and I argue that ANT could contribute a more nuanced arguments to cyclo-advocacy with detailed description of connections between cyclists and urban environment, focus on embodiment and emotions and highlighting the role of materialities. It could thereby provide a stronger argument for furthering the pro-cycling development. Key words: urban cycling, automobilism, actor-network theory (ANT), cycloadvocacy, critical theory, materiality