This paper is explorative in both theoretical and empirical terms. Theoretically the paper explores the potential of merging and including ‘assemblage theories’ into mobilities research. Empirically the paper explores the battle of mobilities between bikes and cars in the USA. With the bicycle as an emerging alternative mode of mobility in American cities, there is a call for a re-evaluation of the automotive dominance of the street. The bicycle is often presented as the ‘caveman’ in the history of urban mobility, though some scholars argue it ought to have a more constitutional role in contemporary mobility practices (Furness 2010). In a contribution to the repositioning of the bicycle, the qualities and positive impacts of bicycling on urban life are discussed (Jensen 2007, Petersen, 2007). Repositioning and reevaluating the car in American society implies examination and discussion of the main ideas and discourses that led to its status as the ‘King of the Road’. This paper theorizes this theme through a framework that includes both cultural and social agents (Jensen 2010), as well as infrastructural networks and systems (DeLanda 2006, Latour 2005, Farias & Bender 2010). The emerging ‘Biking Assemblages’ of American cities are related to the existing hegemonic systems, norms, and practices related to the car. This paper contains empirical field studies conducted in the city of Philadelphia, USA where the ongoing dispute between car-drivers and bicyclists, in news media termed ‘bike wars’, will be examined. Issues of planning practices, law enforcement, power, cultures, and material design practices will be involved as the paper explore the changing practices of the US mobility battle as a window into the debate on future mobility practices.