Greubel Forsey: Balancier Convexe S2: high watchmaking squared
3 October 2023One of the most beautiful things about Greubel Forsey’s watches is their absolute lack of banality. What is obvious and boring about a watch like, for example, the Balancier Convexe S2? Just nothing. We discovered this watch in 2022, with titanium case and bracelet or rubber-effect fabric strap: one reference with a charcoal gray dial limited to 88 pieces and one with a light gray dial limited to 64.
Here it is again today, the Balancier Convexe S2, with its case in an unmistakable shape forged in carbon – once more choosing lightness first, over titanium, thanks to a material that Greubel Forsey has been studying for many years. A work that needs patience and technical mastery, and that gave this carbon watch a complex, architectural shape, with top-level finishes.
COMPLEX BEZEL AND CASE
The Balancier Convexe S2 is an evolution of the Balancier S, keeping the same case shape, while the clearest difference lies in the design of the bezel. Rather than the words ostentatiously engraved on the Balancier S, the titanium Balancier Convexe S2 and the new carbon version opted for a more traditional beveled design.
Although visually it appears simpler, it is far from banal. When viewed from the side, the entire case profile is curved upwards, including the bezel and sapphire crystal. This variable geometry approach leads to a remarkably complex shaping and finishing process, allowing the bezel to appear virtually flat when viewed from above.
The case has an unprecedented diameter of 41.5 mm. Mathematically, with a smaller diameter, its curves should have been steeper. But the Greubel Forsey teams have reworked the convex profile, which is unique in the world, adapting its precise angles and proportions rather than going for simple homothety. The new case has been completely redesigned to provide optimum comfort on the wrist, while maintaining Greubel Forsey’s own expectations for ergonomics and excellence.
Timepieces slip more easily under a fitted sleeve or can be worn casually on a bare wrist. Depending on their preference, collectors can hide or reveal the mechanics of the movement, without appearing ostentatious. Thanks to the totally redesigned caliber, the wearability of this timepiece is definitely better.
Sapphire crystal is a very difficult piece to make in itself, shaped into an arched curve which doesn’t produce any visual distortion or enlargement of the dial. The contoured sides of the case have also been reworked by Greubel Forsey compared to the original Balancier S, as has the crown, which presents larger teeth and a more complex finish.
GREUBEL FORSEY AND THE ART OF CARBON
But it’s not just a matter of bezel, because the choice of carbon for the case was quite a challenge for the engineers at Greubel Forsey. Shaping it to take on such a complex geometry as that of the convex case of the Balancier Convexe S2 requires a precise combination of temperature and pressure.
Anyone who knows a little about materials technology knows that heat makes carbon more flexible to work, while pressure allows to shape it as desired. Obtaining this shape for a conventional case usually requires two tons of pressure per square centimeter. Obtaining the convex case of Greubel Forsey instead, 16 tons per square centimeter were needed: eight times more than usual.
Thus, the case of the Balancier Convexe S2 is much denser than normal because, to create it, the Greubel Forsey engineers multiplied the carbon layers, each of which measures from 1 to 5 microns. The result is a combination of technique and aesthetics well known to the atelier’s manufacturing.
DIAL OR WORK OF ART?
Everything in a smaller size, since the carbon case of the Balancier Convexe S2 measures 41.5 mm (44 with the crown), compared to the 46.5 mm of the Balancier Convexe S and the 43.5 mm of the Balancier Convexe S2 in titanium. A proportion shrink that does not affect the readability of the dial, which keeps its predecessor’s general layout while refining and simplifying the details.
Its surface leaves behind the fluid and complex curves of the case, favoring sharp angled planes. The curved dial edge at 12 o’clock reinforces the overall feeling of depth, but the visual highlight of the design remains the 30-degree tilted plane that cuts across the dial from 5 o’clock to 9 o’clock. This architectural element gives the watch a unique feel, but also assumes a functional purpose for the inclined balance wheel.
By positioning the skeletonized balance bridge and the oversized balance wheel at a 30-degree angle compared to the rest of the Balancier Convexe S2‘s movement, Greubel Forsey better counteracts the effects of gravity on the watch for greater precision. The overall elegant and coherent design is dominated by black.
Between 3 and 4 o’clock stands the double skeletonized arch bridge, which gives the structure such depth that the gear train below appears to be suspended. This bridge, patented in 2019, has become one of Greubel Forsey’s aesthetic signatures – an expression of a powerful and creative vision of fine watchmaking. All this together with an extremely high finishing level of the titanium components, with multiple internal corners.
The power reserve indicator at 2 o’clock, with a design inspired by a fuel reserve indicator, balances the presence of the small seconds counter at 8 o’clock. The grained bridges and main plate are harmonized with the carbon case, as well as the double barrel cover, which now features a black treatment. The raised engraving on the lid itself blends seamlessly with the redesigned case.
THE MOVEMENT’S ARCHITECTURE
The movement is a hand-wound caliber assembled with 303 components and equipped with a 72-hour power reserve with a perfectly defined architecture, and three large hand-decorated bridges on the side of the movement. It has a fast-rotating double coaxial barrel mounted in series (which completes 1 revolution in 3.2 hours). One of the barrels is equipped with a sliding mainspring to avoid excessive tension. The frequency: 21,600 vibrations/hour. The balance wheel has variable inertia with six mean-time screws.
In addition to the mechanical excellence typical of Greubel Forsey calibers, the movement of the Balancier Convexe S2 stands out also in terms of finishing. The bridges and plates on the dial side are made of carbon and titanium, with polished and grained bevels and countersinks, and black treatment. The suspended, skeletonized arch bridge also has a black treatment, polished bevels and countersinks.
As expected from a brand like this, the same attention to finishing is also paid to the caliber on the movement side, visible through the sapphire crystal case back. The architecture is best expressed on the balance between the bridges with a “frosted” finish and polished edges, and the gold plate engraved with the number of the limited series is beveled and flared with straight-grained sides.
GREUBEL FORSEY’S ORIGINALITY
Like the titanium version, this carbon version is also made in a limited edition. And in smaller numbers, given the complexity of producing such a case. The new Balancier Convexe S2 will be produced in two limited editions of 22 pieces each, one with the small seconds with blue treatment and one with black treatment, matching structured rubber strap, and titanium and carbon buckle. At a price of 258,000 euros.
Despite its simplicity, therefore, the new Balancier Convex S2 is anything but ordinary. Every aspect, from the carbon case to the movement and even the strap, has been conceived by the brand to create a unique and original piece. As written above, Greubel Forsey is not a banal brand: here stands the proof.
By Davide Passoni