This thesis investigated mode choice behaviour in Vienna (Austria) and focussed on whether cycling promotion in a city with high shares of public transport and walking and a mobility culture based on public transport increases the share of sustainable mobility or mostly leads to a shift between such modes and how people give meaning to their mode choice behaviour and its change. The case study utilized critical realism as its philosophy of science. A quantitative survey (n=191) among utilitarian bicycle users and nine in-depth qualitative interviews were conducted. The research was based on the principles of the Mobilities Turn as a broader framework and utilized the theories Staging Mobilities, Structural Stories, Perceived Accessibility and Motility. Findings showed that most bicycle users were using other sustainable modes before they took up cycling. The contribution of the uptake of cycling for reaching the municipalities development goal of increasing the share of sustainable mobility is likewise modest. The research furthermore illustrated that there are no plain and simple causal explanations for the personal mode choice behaviour and that important aspects are differing on an individual level but also overlap in many regards. The most relevant factors that keep people from cycling in Vienna are connected to infrastructural aspects as well as personal and societal perceptions of cycling.