This ethnography follows mobile trajectories on roads in Nairobi to investigate how the transformation of transport infrastructure has affected people’s everyday mobility. I follow diverse mobile actors, including pedestrians, handcart (mkokoteni) workers, and minibus (matatu) operators, whose practices and ideas of moving are central to understand the city’s ordinary mobility. I also situate their everyday ways of moving in the rules, plans and ideas of regulators, such as government officials, engineers and international experts, who focus on decongesting roads and attempt to reshape Nairobi’s better urban mobility. Despite official and popular aspirations for building new roads and other public transport infrastructure, I argue that many mobile actors still pursue and struggle with preexisting and non-motorized means and notions of moving that are not reflected in the promise of and plans for better mobility. This ethnography also reveals how certain important forms of ordinary mobility have been socially marginalized. It explores what kinds of difficulties are created when the infrastructural blueprints of road “experts” and the notions that politicians promote about a new urban African mobility fail to match the reality of everyday road use by the great majority of Nairobi residents. By employing mobile participant observation of the practices of moving, this study also finds important ethnographic implications and suggestions for the study of mobile subjects in an African city where old and new forms of mobility collide.