Over the last two decades, cycling in Germany has increased by more than 40%. This paper analyses how this overall increase is broken down by group, characterised by residence (rural and smaller towns vs. medium-sized and larger cities) and education (high vs. low). It analyses (1) how the composition of the population changes according to these groups, (2) how cycling behaviour develops within these groups, and (3) how the changes in composition and behaviour shape the overall volume of cycling. Data on mobility behaviour comes from the large-scale, representative German Mobility Panel from 1996 to 2018, and the analytical sample covers information on more than 28,000 persons over approximately 730,000 reported trips. Data on changes in population composition comes from the German Socio-Economic Panel. Results show that the increase in cycling is unbalanced and largely a consequence of highly educated people in cities who now cycle twice as much and whose share of the population has doubled. This reveals that the cycling boom is bypassing important parts of the population, which limits the contribution of cycling to sustainability goals. Furthermore, the uneven evolution of cycling amplifies social inequalities in finances and health. Finally, this paper shows that increased cycling comes not only from changing behaviour within groups, but also from altered population composition. The most impactful compositional shift is the increasing level of education, which will likely continue to boost cycling.