Tech Talk: Montblanc’s TimeWriter II Chronographe Bi-Fréquence 1000

Like TAG’s Mikrotimer, Montblanc’s Bi-Fréquence employs two separate mainsprings, oscillators and escapements – one for keeping the time of day, and one for the chronograph. The timekeeping balance wheel oscillates at a leisurely 18,000 vph, or 2.5 Hz. The chronograph balance oscillates at 360,000 vph, or 50 Hz. Those of you keeping score at home may be wondering how a chronograph running at 50 Hz can measure 1/1,000 of a second, since 50 Hz is the frequency required to measure 1/100s of a second. How does Montblanc measure milliseconds with such a “slow” oscillator? That’s where Gomila’s childhood hoop comes in.

Typically, there is a direct relationship between the speed or frequency of a chronograph’s escapement and the fractions of seconds it can measure. The famous Zenith El Primero movement beats at 5 Hz, or 36,000 vph, and it can measure 1/10s of a second. That’s because the balance wheel makes 10 vibrations, or back-and-forth rotations, per second.  Multiply that by the 60 seconds in a minute, then again by the 60 minutes in an hour, and you have the 36,000 vibrations per hour rate. If you multiply the El Primero’s rate by 10, that yields 50 Hz, or 360,000 vph, which can measure 1/100 of a second. Ten times faster still is 500 Hz, or 3.6 million vph, which can measure 1/1,000 of a second. That’s what TAG’s Mikrotimer does.

Montblanc takes a very different route to achieving millisecond resolution for its watch. Its chronograph escapement operates at 50 Hz, so it can measure 1/100s of a second. However, Montblanc adds a special wheel that it calls the “thousandths wheel,” or mobile de millième in French. This wheel is Gomila’s childhood hoop. The “hoop” receives an impulse from the chronograph gear train (the childhood stick) that causes the mobile de millième to rotate 10 times per second. Quoting Montblanc, the rotating mobile de millième “provides the resolution with which hundredths of a second can be further subdivided into sets of 10 increments.”

Montblanc has not yet revealed the exact nature of the interaction between the chronograph gear train, the mobile de millième, and the 1/1,000-of-a-second indicator. That may be because there are two primary and 24 subsidiary patents pending on the system that translates a lower frequency into timekeeping resolution that would normally require a higher frequency. Schmiedt noted that Montblanc’s translation principles will work with other frequencies.

We can report that the prototype watch we examined started, stopped and reset perfectly, and the 1/1,000s of a second display appeared to function as described. Of course, it is not possible to discern with only a pair of eyes whether 1/1,000s of a second are actually being measured. Montblanc says it has tested the watch with a stroboscope to ensure that it is in fact measuring the milliseconds correctly.

Schmiedt did confirm that the movement is fully integrated, and that it is an original, “clean sheet of paper” design – no existing plates or modules were used in the construction. The chronograph functions are controlled by a two-level column wheel: one level guides the start, stop and zero-return functions; the other level controls the 1/1,000s. The mobile de millième does not engage with the gear train in the traditional manner, so it does not increase wear and tear on the movement. Montblanc considers the movement to be a world first – not for measuring 1/1,000s of a second, but for the way in which the 1/1,000s are measured.

Montblanc TimeWriter II Bi-Frequence back

Though the chronograph is fast, the reset function is not. It appears to operate in slow motion. This design feature allows the owner to appreciate the complexity of the watch in a subtle and compelling way.

According to Schmiedt, development of the movement took a team working at Villeret two and a half years. Gomila spent 10 months in Villeret last year building the prototype himself. Montblanc’s constructors created the parts, and Gomila assembled everything himself.

The movement has 472 parts, including 45 bearing jewels, and measures 38.4 by 10.6 mm. It is housed in a white gold case that measures 47 by 15.1 mm.

Schmiedt says the Bi-Fréquence meets each of the four challenges recognized by Montblanc: it precisely measures 1/1,000s of a second, it does not suffer wear-and-tear-related issues, it is easy to read, and the chronograph’s power reserve makes it useable in real life.

A total of 36 pieces will be produced, priced at $305,900. Montblanc’s target is to deliver the first piece by the end of the year, and to deliver one or two pieces per month after that. The series is not yet completely sold out, but according to Schmiedt, “a large part” of the production is pre-ordered. Schmiedt expects that it will take about two years to deliver all of the pieces. Apparently, measuring milliseconds is not a fast process, after all.

Click below for a video of the Montblanc’s TimeWriter II Chronographe Bi-Frequence 1.000…

Receive all the news, features and reviews from WatchTime for free! Sign up to our free weekly newsletter and get all the news delivered to your inbox.


No Responses to “Tech Talk: Montblanc’s TimeWriter II Chronographe Bi-Fréquence 1000”

Show all responses
  1. Muhammad Usman

    can i have the price of Montblanc’s TimeWriter II Chronographe Bi-Fréquence 1000 ?

  2. MrTissot

    This is a truly amazing piece of horological art. It;s just a shame that the dial is soooooooo busy!

Leave a Reply