Zenith El Primero Stratos Flyback Blue Bracelet (03.2067.405/51.M2060)

The Zenith Striking 10th "Stratos" is a celebrity: it has hurtled through space at more than 1000 km/h, on the wrist of a certain Felix Baumgartner. That was on October 12th 2012 and it remains the ultimate test of any watch in history.

Nonetheless, this exceptional piece is available to enthusiasts who have their feet on terra firma! They may be thrill seekers, but a long way from throwing themselves into thin air - in the true sense of the term - from the stratosphere.

To be completely sure of the model's strength, WorldTempus decided to put it to the test in the most extreme conditions possible, but on Earth: namely, the Arctic Circle. The test conditions: a week, 200km north of the Arctic Circle, on a snowshoe trek.

-42°C in the tundra
The Zenith Stratos is the result of alchemy: on the one hand, a legendary movement, the El Primero, known for its precision to 1/10th of a second; and on the other, the "Stratos" finish, created for the occasion, which consists of an enlarged, more robust format, with a double folding clasp, a rubber strap, a solid back and a ceramic bezel. A sturdy protection against knocks and jolts. But what about resistance to extreme temperatures?

Our plane landed in Kittilä on a frozen runway lost in a sea of white. The week before our arrival, the barometer hadn't moved from -42°C. When we landed, it was hovering around a "mere" -22°C. So the first contact between the cold and the Stratos was icy!

The movement appeared to be completely unconcerned by the surrounding temperature both the day we arrived and during the days that followed. The rubber strap on the other hand, froze and threatened to break. With the piece worn in the traditional manner on the wrist, this will not happen. Worn Felix Baumgartner style over his suit, it might be more of a problem for longer than a few hours of exposure at -20°C.

Hiking in the tundra totally suited the Stratos. The regular movement of the wrist and sticks and the walking seven hours a day are all exercises that wind the barrel continuously. The consistently maximum torque delivered to the escapement never suffered. The Stratos guarantees a daily rate variation of -2 seconds, a result well above the usual standards for this type of chronograph.

A Stratos, an axe, and an ice bucket
More athletic exercises were also in store. These included almost daily breaking the ice of a Finnish lake to obtain the water required to cook meals. And the ice had to be shattered with an axe, even on the surface of the lake. Would this prove violent for the Stratos? In any event, it's a test that needs to be conducted on a model that claims to be resistant to anything and everything!

In the end, the dozen or so blows from the axe into the ice caused no damage at all to the movement, despite the unimaginable, repeated violence of the shocks. On the other hand, a few days later, the hand of the chronograph minute counter mysteriously stopped on 4, before returning to its place during the next timing operation. Was that a direct effect of the axe blows? Frozen oil or gears? We will never know - and it doesn't really matter because it never happened again.

Stratosauna
Brutal temperature variation is also a tricky issue for sports watches. The Arctic Circle is perfect for playing this game: after a long day of walking in a blizzard, what could be better than succumbing to the local custom and taking a sauna?

Admittedly, this exercise is pretty unusual in everyday life, since it corresponds to experiencing a temperature range of more than 80°C in just a few minutes. In this case, the element that takes the most 'heat' (pun definitely intended) was the waterproofing of the case. The seal compresses and then dilates suddenly, running the risk of letting in air… and damp, of which there is plenty in a sauna.

The verdict? The Stratos goes from a blizzard to the tropics without the slightest problem! The watch shows no sign of humidity whatsoever, even in the working of its chronograph, while the strap enjoys the benefit of going back to being as flexible as it was to begin with. What more could one want?

Luminescent, but not yet capable of pitching the tent for you
One certainly appreciates this generously sized strap in daily life. It means the watch can be worn on the outside of one's clothes, no matter how thick. In the Arctic environment, this is a major issue for two reasons. The first is that wear designed for "extreme cold" does not allow one to consult one's watch without uncomfortable stops to take off the required number of layers required by the surrounding temperature.

The second reason is that despite these clothing obstacles, it is essential that one keeps an eye on the time, in a region where the sun sets (during the period when the tests were conducted) at 14:50. It is undoubtedly possible to end a trek with a head torch at night and to pitch a tent in temperatures of around -25°C. The Stratos is certainly luminous and would be happy to put up with it. Not us!

What is the Stratos lacking to pass these tests? Nothing! After a week spent 200km north of the Arctic Circle, the piece returned to its Swiss fold as if it had never left it. The well-born movement remains a benchmark. The Stratos finish provides an additional layer that will withstand anything. Undoubtedly, to be truly comprehensive in our testing, we should have descended to 1000m - this time not of altitude but depth. Lapland's lakes were not ideal for this. What a pity - we'll have to go on another trip…