Striking a balance between simulation realism and immersion is essential for the development and evaluation of a prototyping environment (set-up and methodology) for Mixed Reality Road bicycle racing applications. Multi-sensory immersion, safety, usability, and design process iterability are hard requirements for the proposed prototyping environment in which a tandem rides on a treadmill with a participant riding up-front wearing a Virtual Reality headset. In the virtual environment, with interactable interface artefacts in a 360-video sphere, participants’ needs and preferences are dis-covered as participants configure their own 3D user-interface for Mixed Reality capable cycling glasses. Sessions that simulate a cycling race, focus on two distinct scenarios of ascending and descending. Two prototyping methods, while standing and while riding a bicycle, are evaluated and compared. Cyclists’ preferences include types of information, their placement in the visual field, size, and colour, depicted in heatmap visualisations. These insights are essential for designers of Mixed Reality systems with real-time information for outdoor bicycle racing.