In this feature from the WatchTime archives, we take a look at the Montblanc TimeWalker TwinFly Chronograph, with its two central elapsed-time flyback hands.
In 2011, Montblanc unveiled the Montblanc TimeWalker TwinFly Chronograph, which contains a caliber called the MB LL100. The movement has an unusual feature: a center-mounted elapsed-minutes hand. Such hands were common until the mid-1970s, but have since become rare. Rarer still: the elapsed-minutes hand, like the elapsed-seconds hand, is a flyback hand. This feature is the source of the name “TwinFly.” The MB LL100 has certain features in common with Montblanc’s MBR chronograph calibers, which are used in the brand’s Rieussec watches. (Launched in 2008, their most notable feature is the two rotating disks used to display elapsed seconds and minutes.) These features include the gear train’s translations, the subassembly for the escapement, the column wheel and vertical disk coupling for the chronograph, the setting devices for the time-zone display and date and the movement’s two serially arranged barrels.
When you travel to a new time zone, you can easily reset the hour hand in one-hour increments by turning the crown after it has been pulled out to its middle position. The hour hand is connected to the switching mechanism for the date display, which can be reset either forward or backward. The time in your home time zone is shown on a 24-hour subdial located at 12 o’clock. This subdial is large enough so the Arabic hour markers are easy to read. Daytime hours arc across the upper semicircle. The numeral 12 on the main dial plays a double role because it’s also used as the 12 on the 24-hour subdial. The sunray-like lines represent the sunlit hours in the inner, upper segment of the circle. Midnight is at the lowest point on the arc. Stars symbolize night in the lower, inner part of the subdial. Although these decorations are visible only from certain angles, we found them appealing. The arrangement of the daytime and nighttime hours seems quite sensible, too. If we momentarily ignore daylight saving time and other astronomical details, we can say that it’s noon when the sun climbs to its highest point in the sky and midnight when it descends to the lowest one below the horizon.
To set the second time zone, pull the crown to its outermost position and then turn it to bring the hour hand into the proper position on the subdial. This Montblanc Timewalker watch has a stop-seconds function, so you can synchronize it with a time signal. You can then return the main hour hand to its correct position via the quick-reset function, using the crown pulled out to its middle position. Although there are no odd numbers in the ring of hours for the second time zone, the even-numbered hours are relatively easy to read. The same cannot be said for the applied indices that mark the hours on the main dial. They’re plated with shiny rhodium, but the matte black background seems to swallow them up when you look at the dial from some angles or when light shines on the dial in a certain way. It seems that the designers at Montblanc realized that there could be problems with the legibility of the displays and the visibility of the skeletonized, partly faceted hands: the company has launched two new versions of the Montblanc TimeWalker TwinFly with gray dials that are much easier to read (they’re named “Greytech”). Nighttime legibility is good but we felt that the designers could have left out the luminous markings for the chronograph’s elapsed-minutes scale, which is positioned in the inner part of the dial. They serve no purpose because the elapsed-minutes hand doesn’t glow in the dark.
The slits cut in the hour and minutes hands are intended to improve the visibility of the chronograph’s elapsed-minutes scale. (The elapsed-seconds scale is on the flange along the edge of the dial.) But this solution has its drawbacks. Skeletonized hands aren’t really necessary because the elapsed-minutes scale on the Montblanc Timewalker TwinFly is already larger and more prominently positioned than it is on conventional chronographs. If the elapsed-minutes hand is stopped directly above one of these slits, it covers the slit itself. In the hardest-to-read position, the elapsed minutes cannot be read until you peer through a watchmaker’s loupe and find the tiny outermost end of a mostly obscured index mark beneath the elapsed-minutes hand. But this would be a very rare occurrence.
In general, the design seems to work. Thanks to their red segments, the chronograph hands remain surprisingly easy to read, despite their slenderness. The red tip of the elapsed-seconds hand extends exactly far enough to meet the inner end of each full-seconds index. The marks for fractions of seconds are calibrated to match the four-hertz tempo of the movement, but the elapsed-seconds hand isn’t quite long enough to reach the inner ends of these fractional markings. The red, inner section of the elapsed-minutes hand also doesn’t extend far enough to reach the inner ends of the marks on its scale: we could find no reason why the inner section of this hand, rather than its tip, is colored red. Sometimes the elapsed-minutes counter, like the ordinary time display, is hard to read. This hand’s silvery tip isn’t easy to see, so you sometimes have to estimate its precise position. This minor flaw detracts somewhat from the advantages offered by the elapsed-minutes circle, which is not only large, but is also calibrated for 60 minutes to coincide with the course of the ordinary minutes display. Five- and 10-minute increments are marked by numerals for even better legibility. We also liked that the elapsed-minutes circle on this Montblanc Timewalker watch doesn’t interfere with the arc for the second time zone or with the subdial for the continually running seconds at 6 o’clock, although the circle twice crosses each of these indicators. We compliment the designers on a job well done here.
The little hand on the continually running seconds subdial, like the other hands, is sometimes hard to see. If you want to confirm that your watch is still running, you’re better off checking the chronograph’s elapsed-seconds hand. This hand is larger than the one on the seconds subdial and, assuming that it’s in motion, its red tip is always easy to see. Furthermore, because of the movement’s design, it’s no problem to keep the chronograph running constantly. The vertical disk coupling ensures that the flow of energy between the movement and the chronograph is efficient and doesn’t cause excessive wear. And the improved profiles on the gears’ teeth contribute to efficiency and low wear. However, don’t underestimate how much energy it takes to power four central hands. Beginning at the fourth wheel, the vertical coupling creates a connection to the elapsed-seconds wheel; from there, an intervening wheel establishes another connection to the elapsed-minutes wheel. Variously shaped teeth ensure that the hands for both the elapsed seconds and minutes turn ceaselessly. In addition to these hands and their designated wheels, two heart cams also turn: they serve to return the chronograph’s central hands to the zero position. This is accomplished with one spring-borne lever, which acts on both hearts when the chronograph’s hands are reset to zero.
The movement’s two barrels provide 72 hours of power. Compared with a single barrel, they compensate better for the difference in torque that occurs when the chronograph is switched off and on. This, in turn, keeps the amplitude more stable and achieves a better-balanced rate. Indeed, we found there was almost no difference in the rate when the chronograph was running. With the chronograph switched off and on, respectively, our timing machine calculated average daily gains of 8.7 and 9.0 seconds. The amplitude was impressively stable: it averaged 290 degrees, with a difference of approximately 45 degrees between the flat positions and the hanging ones. Our wearing test reaffirmed the results shown by our timing machine. On the wrist, the Montblanc TimeWalker TwinFly Chronograph, usually fully wound, gained an average of 8.8 seconds per day whether the chronograph was on or off. This performance isn’t quite accurate enough for COSC certification, but it shows very uniform rate behavior in all situations.
The movement, which measures 31 mm in diameter and is 7.9 mm thick, is housed in a shiny stainless-steel case that is 42.9 mm wide. The bezel is narrow, leaving plenty of room for the dial to display the time and its other functions. The crystal is domed and made of sapphire that’s nonreflective on both sides. The back has a window of sapphire and is fastened by six screws. The case is water-resistant to 30 meters, which is somewhat low for a sports watch. It looks most impressive when viewed from the side. From that angle, you can see the watch’s skeletonized lugs, a feature found on other watches in the Montblanc TimeWalker collection. Because of the way they’re constructed, these lugs must be screwed to the case. Concave above and convex below, they look very attractive and also ensure that the 15.4-mm-thick case can be comfortably strapped to its wearer’s wrist. The bracelet, made of stainless steel, is securely fastened to the lugs by socket screws with heads shaped like the brand’s logo, which represents the snow cap on Mont Blanc. The bracelet is distinctive in its design, combining narrow and wide links to create what look like rollers when viewed from the side. It has a double-folding clasp that can be easily opened by pushing its lateral pressure points.
Montblanc’s logo is also present as a lacquer inlay on the crown, which is cut with grooves and squares along its sides. You can use this crown to manually wind the watch easily. The case has a slightly conical shape, so the crown’s tube enters the interior of the case via a kind of cylinder, which is flush with the case and thus invisible when the watch is viewed from above, but extends a bit in the rear. It has an indentation there so a fingernail can be easily slipped between it and the side to extract the crown. The date, which appears in white on a black field in a window at 9 o’clock, changes gradually rather than instantaneously, starting about 30 minutes before midnight and ending approximately 60 minutes after.
The chronograph operates neatly using two cylindrical pushers with rounded tops. Gentle pressure on the push-piece at 2 o’clock starts and stops the stopwatch function. Somewhat more force is needed to trigger the flyback and reset function by pressing the pusher at 4 o’clock. This seems somewhat unexpected for a column-wheel chronograph, but the switching processes run securely. And even if you can’t see with your naked eye what Montblanc describes as the “spectacular return of the chronograph’s two centrally axial elapsed-time hands,” you cannot help but feel respect for so much high-mechanical technology and its manifestations on this watch’s dial. The only flaw (and it’s more than just a superficial one) is the occasionally poor legibility, which Montblanc fortunately has already taken steps to improve.
+ Manufacture caliber
+ Well-balanced rate behavior
+ Fine craftsmanship
+ Good cost-benefit ratio
– Occasionally poor daytime legibility
Manufacturer: Montblanc Montre SA, Chemin des Touelles 10, 2400 Le Locle, Switzerland
Reference number: 104286
Functions: Hour, minutes, small seconds, date, quick adjustment of hour hand and date display, second time zone/24-hour display, flyback chronograph with center-mounted elapsed-seconds and elapsed-minutes hands
Movement: In-house MB LL100 automatic; 28,800 vph (4 Hz); 36 jewels; Incabloc shock absorption; flat Nivarox hairspring, screw balance; 72-hour power reserve; diameter = 31 mm; height = 7.9 mm
Case: Stainless steel; domed sapphire crystal nonreflective on both sides, sapphire window in caseback; water resistant to 30 meters
Bracelet and clasp: Stainless steel with double-folding clasp
Dimensions: Diameter = 42.9 mm; height = 15.4 mm; weight = 180.5 grams
Variations: Various dials; with leather strap ($8,900); Greytech (gray dial) model limited to 888 pieces ($15,320)
This article first appeared in WatchTime’s February 2013 issue and has since been updated with new information.
Original photos provided by Zuckerfabrik Fotodesign