Our mutidisciplinar team observes the mutual influence among the citizenship's initiatives and the policies on the field of biking mobility in Spain. Many operative dimensions have been attempted in order to improve sustainable urban mobility policies. We need to deepen into some aspects: why there are different rhythms and models applied in each city. What social and political factors are influencing sustainable urban mobility policies? What local and global consequences have these policies relating to social democracy? How different social groups contribute to substantive shifts in the sustainable urban mobility systems? We adopt a participatory approach where citizen participation of multiple social agents will be taken into account as both an object of research and a means of debating and promoting bicycling policies. Two cities, Madrid and Seville, in the period 1990-2013, have been examined. The cyclist modal split in Madrid is 0,6% in front of a 6,8% in Sevilla. Probici social movements are currently much more active in Madrid but the institutional support has been stronger in Sevilla. In the frame of the comparison between two cities with different achievements in terms of cyclability, we will go deeply on the madrilienan one, providing a better understanding of the role of citizen participation within sustainable urban mobility policies adding some etthnographic insigths.