Re-shaping infrastructure systems and social practices within urban contexts has been pro-moted as a critical way to address a range of contemporary economic, environmental and so-cial challenges. Though there are many attempts to re-imagine more sustainable urban con-texts the challenge remains how to achieve such change. In this context urban experiments have emerged as a way to stage purposive infrastructure interventions and learn what works in practice. The paper integrates literatures on urban governance and urban socio-technical experiments to extend analytical understanding of urban experimentation. Through a case study of ‘sustainable transport’ experimentation in Greater Manchester, we argue that place-based priorities that inform action on sustainable urban futures are conditioned by non-place-based, particularly national, interests. Our paper makes two key contributions. First, we illustrate how the (narrow) national conditioning of place-based priorities translates in to experimentation in episodic ways that are highly contextual. We detail how national priorities, stipulations and funding are mediated and translated at the urban scale where they set conditions for the range of interventions that are feasible in a particular context. The interventions that follow are then materially embedded in place through experimentation with processes of governing and constituting capacity. Second, we argue that the learning generated through these processes of experimentation is only weakly communicated back to conditioning institutions. The result is that there is strong conditioning of experimentation but weak experimentation with conditions. The paper illustrates how the potential of experimentation is conditioned and thus it brings to the fore the need to understand experimentation politically.