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Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

Cliché alert: sometimes you have to break some rules to be able to achieve what you want. The Greubel Forsey Double Balancier à Différentiel Constant does just that, as it sacrifices some basic principles – like good legibility between, well, 4 and 10 o'clock – in favor of highlighting some mind-bogglingly complicated and eye-wateringly beautiful mechanical feats. Here's the how and the why.

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

Established in 2004, Greubel Forsey has made a name for itself by creating some of the most outrageously complex tourbillon watches the watch world has ever seen – just think of the Quadruple Tourbillon (hands-on here), or the $2-million Art Piece 1 watch (hands-on). The 12-or-so years (and counting) of highly successful collaboration between Robert Greubel and Stephen Forsey has proven to be long enough to allow for some non-tourbillon creations to make their way into the brand's assortment in an effort to push prices down to a much more affordable level. While that still means we are running deep into six-figure territory, this actually positions GF in a way that it allows them to realistically compete with high-complication pieces from major brands such as Jaeger-LeCoultre, Audemars Piguet, and a long list of others.

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

In typical Greubel Forsey fashion, that means not the inclusion of traditional complications such as perpetual calendars (although they have done one of those, and it’s quite incredible), chronographs, or repeaters, but the use of twisted, enhanced, and complex alterations of timekeeping mechanisms. The Greubel Forsey Double Balancier à Différentiel Constant, as its fancy-looking and -sounding name implies, attacks with not one but two balance wheels, coupled by a spherical and constant force differential.

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

Let's unfold the mysteries by first looking at that duo of frantically ticking balance wheels. As they say, "if one is good, then two is better," but that clearly is just the tip of a technological iceberg. The two balance wheels are set on two separate escapement platforms, each of which comprises 71 components. These platforms have been inclined and installed in a way that they are each at a 30° angle with the plane of the movement plate.

The reason for this is as follows: the performance (rate and amplitude) of the balance wheel and spring are strongly affected by the position they are in. When a watchmaker adjusts a movement, he/she will have to find the right balance between the greatly different performances of the movement in different positions. When the watch is laid flat on a table – and hence the wheel and spring are also horizontal – the rate will be considerably different to when you put the watch crown facing down so they are in an almost vertical position.

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

By installing the balance wheels and their platforms at an angle to the main plate and also to one another, each will spend a very limited time in the horizontal and vertical positions (not even when the watch is put down on a table or set vertically in a safe), where the differences and errors are the greatest. An inclined 30° angle sort of works as a constant averaging factor, and because the two balance wheels are set at different angles, at least one of them will always perform more closely to ideal.

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

The question now is how do you turn those rate differences between the two balance wheels into mechanical timekeeping – how do you have the two timekeeping organs drive just one set of hands? The answer is a differential, a very similar system to what you would find in cars. Frankly, as I clearly do not possess as deep an understanding of this mechanism as its creators, please bear with me as I, nevertheless, try and give you a run-down on how it works and why it's in there in the first place. But first, check out this sweet old video that beautifully illustrates how a differential works – dedicate 5 minutes to it, and be amazed.

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

If you take a look at the close-up image just above, you'll see that, in essence, the differential is composed of three wheels stacked on top of one another. The ones on top and bottom are connected to each of the two escapements respectively, while the middle one is connected to the going train or, basically, the rest of the movement. Now, as the balance wheels tick away at their own rate – ideally 3 Hertz or 21,600 vibrations per hour, with both of them running not exactly at that frequency thanks to deviations caused by positional errors – the differential, using the principle explained in the video above, averages out the two.

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

So, to give you an example, if one of the escapements runs at -2 seconds per day and the other runs at +2, the average that the differential delivers to the hands actually is 0 – or perfect timekeeping. So what's that 0-1-2-3 sub-dial have to do with any of this? That is a four-minute counter that is linked to another part of the differential...

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

Greubel Forsey Double Balancier À Différentiel Constant Watch Hands-On Hands-On

You see, as though all that dizzying engineering weren't enough, Greubel Forsey has added a constant force mechanism to the differential. Exposed through a little aperture set into the caseback side of the movement, a wheel and a spring on the underside of the differential can be spotted. This spring, that may look a bit like a hairspring to the untrained eye, is responsible for releasing its energy into the differential, all the way through to the double escapements. This is done so as to counter the effects of waning torque delivered by the two, series-coupled mainspring barrels of the movement as they near the end of their 72-hour-long power reserve. The four-minute counter that we mentioned just above is linked to this bottom gear of the constant force mechanism as it takes it four full minutes to make a complete rotation.

About the Author

David Bredan (abtw_david) is a young watch enthusiast based in Budapest, Hungary. He is dedicated to understanding, revealing and discussing as many aspects of fine watch making as possible. Fascinated by the countless admirable details of haute horlogerie, he strives to discover the challenges linked to the manufacturing of fine timepieces and also those related to chronometrical performance. As much as he loves unfolding the mysteries of mechanical timepieces, he also aspires to successfully capture and share the nuances that separate a fine watch and a masterpiece.
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  • john coleman

    Brilliant, well written article. My new grail watch. Now, where’s my lotto ticket !

  • Ah those entry level watches that just leave you wanting more – the Porsche Boxster syndrome.

    No, seriously what wrist porn. The innovative solution to timing or the incredible finishing – your choice – either one inspires a lot of watch lust in me. Thanks for the review David. Tough duty. Well the taking it off and leaving it with GF is no doubt the hardest part.

    • Berndt Norten

      The waiting is the hardest part

  • Bruce Wang

    Another “piece of art” watch…beautifully craftmanship….and so do the price…..

  • word-merchant

    When I saw this, my first thought was of those paintings of courtesans holding fans up to their faces because their noses had been eaten away by syphilis. And now I can’t get the image out of my mind. Perhaps I am not a natural Greubel Forsey customer. Anyway, lovely photography as usual.

    • Phantom of the Opera perhaps?

      • word-merchant

        Certainly a more palatable image than mine.

  • IanE

    As with all GF pieces, one is happy they exist and stunned by their dedication to haute horlogorie. I’ll probably never see one in the metal, will almost certainly never touch one and will certainly never (in this life-time) own one, but love to read about them. Thanks!

  • iamcalledryan

    I love these. The inclined balance was arguably GF’s greatest invention, as David noted it dramatically reduces the occasions that the balance is in a purely horizontal position.

    Thanks for bringing a little more than the “it’s a differential” explanation for how the two escapements combine forces! The averaging effect of the two is very real, more demonstrable and consistent than a resonance alternative. It halves your chances of a single escapement going off the rails well before it’s service interval.

    As for the look of the thing, straight from the dream-factory.

  • Marius

    I like most Greubel&Forsey watches, but in my opinion, for such an exclusive brand, they release too many models and complications.

    Moreover, as Benjamin Clymer, my role model and hero, argued, the inclined tourbillons and escapements bring a few theoretical benefits, but are not exactly revolutionazing horology. Given that the average price for a GF watch is around $400-500,000, I would expect to see something truly innovative and sensational. The Breguet watch using magnetic pivots and working at a frequency of 10 Hz is a good example of a technology that tries to bring some innovation.

    Lastly, with all the double balance, differential, and constant force mechanism, has GF actually provided the timing rates of this watch? I mean, the article didn’t mention how accurate this watch would be.

    • iamcalledryan

      It was just a couple of weeks ago that I gave the 7727 as an example to refute your claim that there was no innovation in the industry. Glad to see it has sunk in and reversed your opinion!

      They haven’t released accuracy stats on this model from what I can tell, but to conclude that it is marketing is very short-sighted. Don’t forget that GF submitted their double Tourb incline and smashed the international chronometers competition in 2011. There is no obligation on a brand to support their offerings with objective stats (there should be, but there isn’t), nevertheless GF are one of the few to put their money where their mouth is and deliver. This is a simpler system than the double tourb, a differential is a proven insurance measure against declining isochronism, but the weakest link remains the adjustment of the watchmaker – fortunately GF have that more than covered with their staff.

      Lastly, the “value” of a watch need not be bound to exponential innovation and complication. It helps, but it is only one reason to invest. Just look at a Rolex Paul Newman or a Patek 1518. And when you look at modern record-breakers, they are not always innovative – the innovative ones go to the collectors who are also total geeks.

      • Boogur T. Wang

        Best statement of the week:
        “Lastly, the “value” of a watch need not be bound to exponential innovation and complication.”

        To paraphrase the old addage: “Value is in the eye of the beholder.”
        Many factors in that matter of ‘perceived’ value.
        “You want it? What’s it worth to ya?”
        Same game – different item.

  • Ulysses31

    G&F are master engineers but their designs are all over the place. The chopped-off dial frankly looks a bit clumsy, and the hands are far from the prettiest i’ve seen. Ignoring the odd looks, the really important aspect of this watch is the accuracy it can achieve with that clever mechanism – you don’t implement all that gear if not for superlative accuracy, which is… what? Is there any actual, real-world performance improvement, or is it yet another contraption meant purely for show? Because you know what guys? I caught a fish once, and it was THIS BIG. How big? Really frickin’ big, let me tell ya. I didn’t weigh or measure it, but trust me on this.


    legibility in this case I will give a pass due to the level of art displayed but the min hand goes to the outer min dial so legibility is not even affected that much. this is more of a sit down on a table and watch it work kind of watch in my book to truly appreciate all the pieces working together. One thing I would do is remove the red square for the PR. really distracting but at 350K GF might be willing to get rid of it.

    • DanW94

      Agree, If you look at this watch and focus on the legibility and accuracy then you just can’t see the forest for the trees. This is about the exposed angled balance wheels and that beautifully crafted differential mechanism, along with the quintessential GF finishing. It’s magnificent. David, great write-up and explanation of the watch and I love those old “how things work videos” (Hamilton did some of those in the 40’s and 50’s on how a mechanical watch works)

      • iamcalledryan

        I’ve never seen a differential given so much stage-space; it’s really awesome.

  • cg

    Arrrgh! The Terminator Watch! The beauty of empty space!

  • Raymond Wilkie

    Looks like a bit of the face has snapped off.

    • iamcalledryan

      Happened during shipping. Want more sturdy dial? You need to pay more….

      • Raymond Wilkie

        MOOOOOORE ! ………………………………………. ( Oliver ! ref )

        • iamcalledryan

          Please, Mr Greubel, Mr Forsey, can I have more dial?

        • wallydog2

          “Shut up and drink your gin!”……………………………… (Oliver! ref.)

  • Larry Holmack

    I guess if ya got $350 grand hanging around that you just don’t know what to do with….well…you’ll make the folks at GF really happy.

  • wallydog2

    I think there should be a separate section for the ABTW faithful to pass judgment on the shirt and/or sweater sleeves included in the pictures of these fabulous watches.

    • Spangles

      We could have a sub-section about watches and the primary site could be shirt critique.


  • Sevenmack

    I should love this watch. I really should. But it leaves me cold. Thw partial skeletonization is nice. The balance wheels are lovely. But it just seems incomplete and not just because half the dial was ripped off like the sleeves on a ball gown. The hands, in particular, don’t dot the rest of the watch.

  • Coert Welman

    My major problem with this watch is that from a distance, it looks like a cheap, blingy, open-dialled Fossil. Or some similar fashion brand. It is only upon close-up view that one can see the excellent finishing.

    • Beefalope

      Are you buying the watch for yourself or for some other guys who’s looking at it from a distance?

      • Coert Welman

        Fair question.

    • iamcalledryan

      There’s not a fashion watch out there that I would confuse for a GF even from 20 paces. Regardless, even a Patek looks like a Quartz Frederique Constant from a distance.

      • Coert Welman

        Might be. I suspect the quality of the photos in the article don’t do it justice. That said, my statement above was my first impression when I opened the e-mail newsletter and saw the picture. Sadly, first impressions last.
        Maybe a bit of a disclaimer, this style of watch in general doesn’t do it for me, which means I might have been a bit more critical than I needed to be. Thankfully, I will never be in the market for a watch like this, so I am spared the decision. It literally costs 2.5 times as much as my 5 bedroom house (in the small town in South Africa where I live, you can get quite a lot of house for your money).

    • Sevenmack

      That would be an insult to Fossil. That company has made better watches than this one.

      • Coert Welman

        I won’t go that far. Here in South Africa, we get the dregs of the Fossil barrel. Rumour has it that Fossil make proper mechanical watches, but those don’t reach our shores. We only get the fashion watches.

  • Jerry Davis

    No, I don’t think so. It does look…. broken.

  • Beefalope

    Nobody puts out more amazingly jaw-dropping stuff than GF.

  • Nateb123

    For all the praise this is getting, can anyone truly say that this looks better than it would have if they just oriented the movement so that the dial was symmetrical?

    Dial balance just seems so incredibly lost on GF. Move your crown to 2 o clock, don’t jam such an intrusive power reserve onto the dial and this suddenly looks like a proper watch instead of a case and dial thrown onto a movement.

  • Shirley Furby

    The complexity is beautiful except for me the mistake that most of the super talented guys make. Who am I to criticize? Please …please… please make the screw heads match, i.e. if the screws are on either end of a piece, don’t tighten them till they don’t align. If this is not possible design a screw head that is always aligned regardless, multiple slots etc. Balance is important, at least to me.

  • Dr. Dunghorse


  • funNactive

    I usually like odd, different or off balance, but this design with the partial face doesn’t quite work for me – make it a complete skeleton.

  • Forever Great

    It’s art. From artist watchmakers. There’s an artist who’s works go for an extreme amount of money and instead of paint she uses monkey shit on canvas. So, I’m sure both take talent I’ll never possess, but I’m not wearing that watch while staring at a monkey shit mural. I’ll take a Graham and call it a night.