Scenario analysis
Which GPS watches survive the Lavaredo 120K?
One does, barely. The Lavaredo Ultra Trail 120K is the gentlest race we model, and the only scenario where a watch actually reaches the finish on a single charge. That makes the result more damning, not less. If the mildest 30-hour race still blacks out 5 of the 6 flagships before the cut-off, the marketing battery claims are not a cold-weather edge case. They come apart on an easy day.
The modelled conditions
These are the Lavaredo scenario inputs, chosen to represent a mild late-June day in the Dolomites: sheltered forest and valley for most of the course, with only brief high exposure. They are modelled conditions and chosen inputs, not a field measurement.
- Ambient temperature: 8 °C
- Wind: 3 m/s
- Cut-off window: 30 h (official 120K limit)
The mildest race, and it still breaks them
Neither cold nor wind is the carrying term here. At 8 °C and 3 m/s this is the gentle end of the scenario ladder, the one case that should flatter these watches. It does not. Even here, 5 of the 6 flagships black out before the 30-hour cut-off, covering only 63 to 83 percent of the window. Enduro 3 Solar Sapphire is the only one to reach the line, clearing it by about 20 minutes and the single device to pass the full window. That is the honest exception in a narrow sense only: it still finishes roughly 49 percent under its own GPS-hours claim. Across the set the Reality Gap, marketing claim against modelled blackout, runs from 42 to 79 percent.
How far each watch gets
| Device | Claim (h) | Blackout ETA (h) | Window coverage | Reality gap |
|---|---|---|---|---|
| Fenix 8 51mm Solar Sapphire Garmin | 84h | 21.7 | 72% | 74.2% |
| Fenix 7X Solar Sapphire Garmin | 89h | 18.9 | 63% | 78.8% |
| Enduro 3 Solar Sapphire Garmin | 60h | 30.3 | 101% | 49.5% |
| Vertix 2S Coros | 43h | 25.0 | 83% | 42.0% |
| Apex 2 Pro Coros | 75h | 24.9 | 83% | 66.8% |
| Vertical Titanium Solar Suunto | 60h | 21.9 | 73% | 63.5% |
Window coverage is the share of the 30-hour cut-off reached before blackout. A figure over 100 percent means the watch covers the whole race with margin to spare; Enduro 3 Solar Sapphire is the only entry above it.
What that means on the route
- Fenix 8 51mm Solar Sapphire: blackout around hour 22, short of the 30h cut-off.
- Fenix 7X Solar Sapphire: blackout around hour 19, short of the 30h cut-off.
- Enduro 3 Solar Sapphire: clears the 30h cut-off with roughly 20 minutes to spare, then still well under its claim.
- Vertix 2S: blackout around hour 25, short of the 30h cut-off.
- Apex 2 Pro: blackout around hour 25, short of the 30h cut-off.
- Vertical Titanium Solar: blackout around hour 22, short of the 30h cut-off.
Field validation: none yet
These mild-weather conditions are physically modelled but not independently field validated, the same status the methodology page states for the reference scenario. The figures are model output under one fixed scenario, not measured runtime, and we make no stronger claim here than on any device dossier.
Why only these six
This page covers only the six devices whose display power is traced from documented sources. The AMOLED watches added later share a single baseline display figure rather than per-device measurements, so publishing scenario numbers for them would rest on an unsourced placeholder. We leave them out until that input is sourced.
Audit your own route to see where a specific device blacks out on your GPX, segment by segment.
DATASET · HIKINGSPECS LAB · FORMULA v1.0 · CC BY 4.0
Physics-derived estimate under one fixed scenario. The model is calibrated but not yet independently validated against measured field runtime. Estimated hardware inputs are labeled as such. Full method at /methodology.