On a sunny Sunday afternoon in 2012 a conflict arose between two men riding a popular mountain biking track in New Zealand. The bulk of this was filmed from a helmet-mounted action camera, facilitating a single case analysis of the transition from an everyday trouble to an unexpected violent ending. The two riders come across each other travelling downhill at speed on a narrow track. Unease quickly develops for the camera-clad rider wants to pass the rider in front, but except (...) for an intriguing and brief interlude, the first rider will not let the other pass. The second rider grows frustrated, progressing to tailgate the ‘slower’ rider, in the midst of which he invokes a rule of mountain biking conduct. The reflexive implications of the rule-invocation need to be seen to be believed. The video is used as data to get close to such seeing, and despite some limitations, we can see a clear trajectory where the rule significantly contributes to a moment of phenomenological salience. Thereafter, it becomes witnessably relevant to the conflict that develops. (shrink)