During an ethnographic research project exploring young people's perceptions of living in a post-industrial semi-rural place, boys aged 13/14 years revealed their semi-clandestine motorbiking activities across mountains trails. It was found that riding motorbikes and fixing engines were potential resources for young boys' transitions into adult working-class masculinity and sources of competence, pride and enjoyment that mimetically referenced the industrial past. The study engages with Deleuze and Guattari's theory to explore relations among rider-machine-territory as dynamic Assemblages that fuse elements from technical, psychological and cultural media to show how motorbiking in different situations afforded boys more or less autonomy. The study argues that an epochal shift in the UK from an industrial to post-industrial base has changed the value attached to motorbike riding on mountain trails creating biking Assemblages that territorialise boys as social nuisances and potential criminals under police surveillance.