Kairn Design Studio — Embedded UI Design for Hardware Products
A freelance product design mission at the intersection of hardware and digital experience — designing embedded interfaces for an e-bike motor ecosystem and an avalanche transceiver, where the interface cannot afford to fail.
Project context
- Role
- Freelance Product Designer — UX research, interaction design, UI system design, Figma prototyping and handoff
- Timeline
- 2024–2025 · Two parallel product tracks, handled simultaneously
- Tools
- Figma · Figma Variables · Figma Auto Layout · Prototyping · Design system documentation
- Products designed
- E-bike motor UI ecosystem: top-tube display (minimal, glanceable) + handlebar dashboard (structured navigation)
Avalanche transceiver (DVA): life-critical directional interface for search-and-rescue — ongoing - Physical constraints
- Hardware-bound screens. No touchscreen. Operated with gloves, in rain, direct sunlight, freezing temperatures. Real-time safety-critical feedback with zero margin for misinterpretation.
- Why this project
- After several years designing web interfaces and geospatial tools for professional users, this mission pushed that same logic into a radically more constrained context: screens you cannot touch, in conditions where a wrong read can cost a life.
The problem
Two products, one shared constraint: the user cannot look away.
Whether riding a trail at speed or searching for a buried person under avalanche stress, the interface has to deliver critical information at a glance — without demanding the cognitive load that the situation cannot afford. The challenge is not to design something beautiful. It is to design something that disappears when it needs to, and surfaces exactly the right signal at exactly the right moment.
The real design problem wasn't "how do we show speed and battery level." It was: what is the minimum legible unit of information a rider or rescuer needs, and how do we make that unit unambiguous under the worst physical conditions we can anticipate?
Research & constraints
The client had already conducted persona research. We used those personas as the foundation and extended them through our own constraint analysis — mapping the physical conditions each interface would have to survive before defining a single screen.
For the e-bike, that meant understanding the difference between a casual urban rider checking battery levels at a red light and a trail rider who cannot take their hands off the bars. For the DVA, research focused on the cognitive state of the user during a rescue: acute stress, tunnel vision, degraded motor control from cold, time pressure measured in minutes.
- Client-provided personas: two distinct rider profiles for the e-bike, with documented use contexts and environmental conditions
- Physical constraint mapping: screen size, ambient light levels, glove interaction, viewing angle and distance per product
- Competitive audit: analysis of existing e-bike HMI systems (Bosch, Shimano, Specialized) and professional DVA interfaces (Mammut, Ortovox, Arva)
- Scenario modelling: edge cases defined before wireframing — what happens in direct sunlight? What happens if the rider has one hand on the bar?
Design decisions
Every significant decision on this project was a trade-off between information richness and cognitive load — and the trade-off was never made in the designer's favour. The products set the terms. The design responded.
The two products required distinct solutions, even when the underlying design language was shared.
One visual system, two very different screens
The top-tube display and the handlebar dashboard share a design language — type scale, colour coding, iconography — but serve completely different use cases. Figma Variables managed the shared tokens; the layout logic diverged deliberately from there.
Glanceability as the primary design constraint
On the top-tube display, every element that was not readable in under 300ms was removed. Battery level, assist mode, a single speed indicator. The handlebar dashboard introduced progressive disclosure — deeper navigation only accessible through deliberate input.
Minimalism as a safety requirement, not an aesthetic choice
Every element removed from the DVA interface was a deliberate functional decision. When the user is panicked and operating in freezing conditions, a cluttered screen is a dangerous screen. If an element didn't directly serve the search-and-rescue function, it was cut.
Unambiguous directional feedback
The core UI challenge was directional: guide a rescuer toward a buried victim using signal strength and bearing. High-contrast arrows, proximity rings with dynamic scaling, a reduced colour palette with a single high-salience accent — interpretable without any prior reading.
Transmit / Search mode states: visually undeniable
Switching between Transmit and Search modes is the most critical transition in the device. The interface state change had to mirror the physical hardware switch — impossible to misread, impossible to miss.
Process & iterations
The iteration process on both products followed the same logic: start from the constraint, not from convention. Existing HMI patterns for e-bikes assume touchscreens and seated users. They were useful as reference points and as things to consciously reject.
Early wireframes were deliberately rough — the goal was to pressure-test the information hierarchy before touching visual polish. Key questions at the wireframe stage: what survives when you squint at it? What survives when you hold it at arm's length in bright light? What survives when you only have half a second?
For the DVA, iteration focused almost entirely on the directional feedback mechanism. The transition from abstract signal-strength numbers to a spatial, directional UI went through several failed attempts before reaching a solution that felt genuinely intuitive under simulated stress conditions.
Outcome & reflections
The e-bike motor ecosystem is currently in its final pre-production phase — the product is expected to reach market in 2025. The UI system designed during this mission feeds directly into the shipped hardware.
The DVA project is ongoing. It has already produced its most important output: a clear articulation of what safety-critical interface design actually requires in practice. Not the safety design principles you read in a textbook — the ones you arrive at when you spend time imagining the worst moment a user could face, and designing backwards from there.
What this project reinforced: physical constraints are the most honest design brief you can receive. There is no room for decorative decisions. The interface either works under pressure or it doesn't. That discipline — designing for the person who has no attention to spare — is something I now bring to every project, including environments far less extreme than an avalanche field.
