The upscaling of innovations from urban experiments is often assumed to be relatively easy, as if they can simply be ‘rolled out’. In practice, however, upscaling is usually constrained by a range of factors in the wider context of the innovation, typically a context of interconnected and ‘obdurate’ urban socio-technical networks and institutions. Innovation studies have used the notion of upscaling from experiments most explicitly in studies of transitions, especially of strategic niche management (SNM) and transition management (TM). However, these studies have focused more on niche internal dynamics and future visions, respectively, and much less on constraints in the present socio-institutional context. This paper offers a conceptual contribution on ‘constraints on upscaling’, elaborating on how upscaling can be more effective when constraints on upscaling are first identified in retrospective systems analysis, and then anticipated in the design of urban experiments. Our focus is on innovation in urban mobility systems. After a conceptualization of ‘constraints on upscaling’, based on a review of the literature of transition, social innovation, geography and science & technology studies, we present a retrospective analysis of urban mobility in Maastricht (NL) in which these interrelated constraints can be recognized. Further, we analyze a pilot on electric bus mobility which was relatively successful in anticipating future constraints. Based on this, we offer some guidelines on how to anticipate upscaling in the design of urban experiments with socio-technical innovations.