Products designed for gloves, rain and vibration keep converging on one physical button. The design challenge is not the hardware — it is building a state machine that fits.
The three-state core
Almost every single-button device settles on the same skeleton: wake/confirm, advance, dismiss/cancel. Short press advances, long press confirms or wakes, double press or press-and-hold dismisses. Riders learn it in one commute because every action maps to an intention (“next”, “yes”, “stop bothering me”), never to a parameter.
Everything else belongs on the phone
The moment one button must adjust volume, the design has lost. Parameters live in the companion app; the device only carries the ride’s essential loop. This division is also what keeps firmware small and testable.
Feedback is half the interaction
With one button, the device must acknowledge every press in kind: a click pattern, a screen flash, a short tone. Unacknowledged presses get repeated, and repeated presses corrupt the state machine. Haptic or audible feedback is not decoration — it is error prevention.
When two buttons are justified
Volume on the handlebar (music riders), or a dedicated safety control. If a second button earns its place, give it a shape difference, not just a position difference — gloves read shapes better than gaps.
Testing the state machine
Single-button devices fail in edge sequences: rapid double presses during a long press, presses during boot, button held through a mode transition. We script these sequences into production test firmware, because a state machine bug found by a rider is found too late.