Roger Dubuis Combines the Inclined Balance and Flyback Chronograph

An all-new calibre for the Excalibur Spider.

One of the latest releases from Roger Dubuis, the Excalibur Spider Flyback Chronograph, makes the most of its openworked dial to show off a newly-developed calibre, the RD780, which combines an inclined balance wheel with an integrated chronograph.

A complex movement with two patents pending, the RD780 is notably elaborate with unusual features like a digital minute counter and twin barrels. And technically-minded enthusiasts will also note the RD780 boasts diamond-coated silicon escapement parts, which are both wear- and magnetism-resistant.

Initial thoughts

Roger Dubuis’ current chronographs distinguish themselves through bold design and flashy technical features. While the style is outlandish, it is refreshing to see this unique approach to a chronograph design, particularly since the technical features are novel and interesting, such as the inclined balance wheel and column wheel, visible through the openworked dial.

But the Excalibur chronograph’s technical merits are perhaps overshadowed by the design, which is excessive in a hyper-mechanical style. The chronograph’s dial is busy, even for an openworked dial. It is not easy to read, even when compared to what is being offered by the likes of Richard Mille, which is perhaps the closest comparison to the Excalibur chronograph.

The Excalibur chronograph is priced at US$101,500, making it more affordable than the equivalent from Richard Mille, the RM 72-01. In fact, the Excalibur is half as expensive as the Richard Mille. But the RD780 in the Excalibur is arguably more sophisticated, particularly with its inclined balance wheel, digital counter, and unusual chronograph construction that has the levers on the back but the column wheel visible on the dial. In short, while the Excalibur chronograph isn’t for everyone in terms of design, the movement is undeniably interesting and certainly lives up to the price tag.

An integrated chronograph

The Flyback Chronograph represents the latest addition to the Excalibur Spider collection, which started with the Double Tourbillon model in 2015 and is characterised by skeletonised carbon composite cases that are a nod to lightweight sports cars. Like other models in the line-up, the chronograph retains the openworked styling on both the case and triple lugs, as well as the notched ceramic bezel. The case is carbon composite and measures 45 mm in diameter, making it quite large on the wrist. 

Stylishly designed, the dial has double scales on its periphery: an inner flange for tachymeter scale, while the outer flange carries the a minute track with alternating white and red accents. And on the outermost edge beyond the minute track is a ring bearing the rhodium-plated, hex nut-shaped hour markers filled with Super-Luminova. The white gold hour and minute hands are likewise openworked, filled with Super-Luminova at the tips and outlined in red. 

At its heart lies the new RD780, an in-house movement. Besides a flyback chronograph, the RD780 features both a column-wheel and vertical clutch, while having a power reserve of 72 hours thanks to twin barrels visible through the open-worked dial. The movement also incorporates two patent-pending innovations — one for the chronograph’s seconds hand and the other for the 120° Rotating Minute Counter (RMC).

The first patent concerns the clutch mechanism known as the Second Braking System (SBS), which improves the stability of the chronograph seconds hand and reduces any stuttering during start, stop, or reset. In the SBS, the brake is directly mounted on one of the two arms that operate together to engage or disengage the vertical clutch. When the chronograph is stopped, these two arms lift the vertical clutch to disengaging it, while the brake simultaneously prevents the seconds hand from moving.

An exploded view of the RD780

The 120° RMC enables the elapsed minutes to be read without a conventional sub-dial. The minute display features three rotating arms carrying the digits “0”, “1”, and “2” respectively. The arms rotate and progress along the outer scale bearing the second digit of the minutes.

The 120° Rotating Minute Counter (RMC)

In addition to the chronograph-related features, the RD780 also sports an inclined balance wheel. Also found in other Excalibur models, the balance wheel is inclined at 12 degrees from the horizontal. According to the brand, this set up better compensates for gravitational errors, while increasing the inertia of the balance. This approach is not unique to Roger Dubuis and has been employed by other respected names, including Greubel Forsey, which installed similar inclined balance wheels in several of its watches, indicating the concept has technical merit.

Alongside the balance are a diamond-coated silicon escape wheel and diamond-coated silicon pallet jewels that are both hard wearing and non-magnetic, a particularly intriguing innovation since brands owned by Richemont (of which Roger Dubuis is one), rarely use silicon components in their movements due to intellectual property constraints.

Key facts and price

Roger Dubuis Excalibur Spider Flyback Chronograph
Ref. RDDBEX1046

Diameter: 45 mm
Height: 16.1 mm
Material: Carbon composite and ceramic
Crystal: Sapphire
Water resistance: 100 m

Movement: RD780
Functions: Hours, minutes, date, and flyback chronograph with 120° Rotating Minute Counter (RMC)
Winding: Automatic
Frequency: 28,800 beats per hours (4 Hz)
Power reserve: 72 hours

Strap: Rubber strap with folding clasp

Limited edition: No
Availability: Only at Roger Dubuis boutiques
Price: US$101,500 

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