MB&F HM9 'Flow' (90.RL.RB): A Horological Masterpiece

In the rarefied stratum of independent haute horlogerie, few entities command the same reverence and fascination as MB&F. Their Horological Machines are not merely time-telling devices; they are kinetic sculptures, each a bold declaration of mechanical ingenuity and a profound reimagining of watchmaking's possibilities. The Horological Machine N°9, affectionately dubbed 'Flow,' stands as a monumental testament to this philosophy, a three-dimensional marvel inspired by the streamlined aesthetics of mid-century automotive and aeronautical design.

Reference 90.RL.RB, the rose gold and titanium iteration with its captivating blue engine, exemplifies MB&F's unwavering commitment to pushing the boundaries of form and function. It is a piece that transcends traditional watch design, inviting the beholder to delve into its complex, biomorphic architecture, where every curve and aperture reveals a facet of its intricate mechanical soul. This review will meticulously dissect the HM9 'Flow,' exploring its genesis, its unparalleled movement, and the singular experience it offers to the discerning collector.

Manufacture History: MB&F – The Architects of Horological Dreams

Founded in 2005 by Maximilian Büsser, MB&F, an acronym for Maximilian Büsser & Friends, was conceived not as a traditional watch manufacture but as a creative laboratory. Büsser's vision was to collaborate with talented independent watchmakers, designers, and artisans to create radical, three-dimensional Horological Machines and more classically inspired Legacy Machines that defy conventional watchmaking norms. Headquartered in Switzerland, MB&F has consistently pushed the boundaries of mechanical art, earning a reputation for audacious design and groundbreaking technical innovation. The Horological Machine N°9 'Flow' perfectly embodies this spirit, drawing inspiration from external influences to craft an entirely new horological narrative.

The Engine: A Symphony of Twin Balances and Differential Precision

At the heart of the MB&F HM9 'Flow' (ref. 90.RL.RB) lies an entirely in-house developed 3D horological engine, a manual-winding movement that is as architecturally compelling as the case it inhabits. Unlike conventional movements, the HM9 engine is designed as an integral part of the watch's three-dimensional form, with its components arranged to be viewed from multiple angles through no fewer than five sapphire crystals. This particular reference showcases a movement where the bridges and plates are treated with a vibrant blue CVD (Chemical Vapour Deposition) coating, providing a mesmerizing contrast to the rose gold and titanium case elements.

The caliber operates at a deliberate frequency of 18,000 vibrations per hour (2.5 Hz), a nod to classic watchmaking, yet its technical execution is anything but conventional. Its most distinctive feature is the presence of twin independent balance wheels, each oscillating freely on opposite sides of the movement. These balances are not merely aesthetic flourishes; they are functionally integrated via a planetary differential. This ingenious mechanism averages the timing rates of the two balances, theoretically enhancing the overall stability and precision of the movement. It is a complex solution to a fundamental challenge in chronometry, executed with MB&F's characteristic flair for innovation.

The movement boasts a healthy 45-hour power reserve, delivered by twin barrels, ensuring reliable operation. With 30 jewels meticulously placed throughout its intricate structure, the HM9 engine is a testament to the highest standards of micro-mechanical engineering. Every surface, every bridge, every screw head is finished to haute horlogerie protocols – from polished bevels and Geneva waves to mirror-polished screws and countersinks. The visual spectacle of these twin balances oscillating in unison, linked by their differential, beneath the sapphire domes, is nothing short of a mechanical ballet. It's a horological landscape designed for constant discovery, where new details emerge with every change in perspective.

Technical Specifications: Form Meets Function

  • Case Diameter (Width): 47mm
  • Case Thickness: 23mm
  • Lug-to-Lug (Length): 57mm
  • Case Material: Rose gold (engine pods) and titanium (central case and engine frame)
  • Crystal: Multiple domed sapphire crystals with anti-reflective coating
  • Water Resistance: 30 meters (3 ATM)
  • Lume: Super-LumiNova on hands and numerals for legibility
  • Bracelet/Strap: Hand-stitched brown alligator leather strap
  • Clasp Type: Matching rose gold and titanium folding buckle

The dimensions of the HM9 'Flow' are substantial, a deliberate choice to accommodate its three-dimensional engine and sculptural case. The 47mm width and 57mm length are considerable, but it is the 23mm height that truly defines its volume. Despite these figures, MB&F has engineered the case with remarkable ergonomic consideration, ensuring it wears more comfortably than its size might suggest. The construction, a complex fusion of rose gold for the 'pods' housing the balances and time display, and titanium for the central fuselage, perfectly balances visual warmth with structural integrity and wearability. The numerous sapphire crystals, meticulously shaped and anti-reflective coated, offer unparalleled views into the mechanical heart, while the 30-meter water resistance indicates its intended use as a refined, rather than utilitarian, instrument.

Wrist Feel: A Sculptural Embrace

To wear the MB&F HM9 'Flow' is to engage in a dialogue with a piece of kinetic art. Its generous dimensions – 57mm in length, 47mm in width, and a commanding 23mm in height – suggest a formidable presence, yet the ergonomic design of its three-lobed case ensures a surprising level of comfort on the wrist. The central titanium case, flanked by the rose gold 'pods,' is sculpted to contour gracefully, allowing the watch to settle rather than perch. The weight, distributed thoughtfully across the wrist, is substantial without being cumbersome, a testament to the meticulous engineering that underpins its avant-garde form.

The integration of the hand-stitched alligator strap with the articulated lugs ensures a secure and balanced fit, mitigating the potential for top-heaviness often associated with watches of this volume. The HM9 'Flow' does not merely sit on the wrist; it becomes an extension of it, an organic sculpture that flows with the wearer's movements. It's an experience that transcends mere timekeeping, offering a constant tactile and visual engagement with its complex geometry and mechanical heart.

Accuracy: Precision Through Innovation

While MB&F timepieces are not typically submitted for COSC certification, the HM9 'Flow' is engineered to an exceptionally high standard of precision. The unique architecture, featuring twin independent balance wheels linked by a planetary differential, is designed to average out rate variations, thereby enhancing overall timekeeping stability. In real-world wear, collectors can expect chronometric performance well within the stringent parameters of high-end mechanical watchmaking, typically within -4/+6 seconds per day. The focus, however, remains less on achieving a specific certification and more on the innovative engineering and the pursuit of horological excellence through novel solutions.

Occasions and Wrist Presence: A Statement Piece

The MB&F HM9 'Flow' is undeniably a statement piece, suitable for occasions where its unique design can be appreciated and celebrated. While its bold aesthetic might lean towards more informal or artistic gatherings, its exquisite finishing and precious materials allow it to seamlessly transition into formal settings, particularly when paired with contemporary luxury attire. It is a watch that invites conversation, making it ideal for social events, art exhibitions, or any setting where individuality and an appreciation for mechanical artistry are valued.

Wrist Presence: 5/5 The HM9 'Flow' possesses an undeniable, almost gravitational wrist presence. Its biomorphic case, reminiscent of jet engines and streamlined automotive bodies, commands attention without being overtly ostentatious. It is a piece that sparks conversation and elicits admiration, a clear statement of sophisticated individuality and an appreciation for boundary-pushing design. It is impossible to wear the HM9 'Flow' and not be noticed; it is a wearable sculpture that defies convention.

Reference Variants and Family Lineage

The Horological Machine N°9 'Flow' was initially launched in two distinct versions, each with two engine color options:

  • 90.TL.B: Titanium case with a striking blue CVD treated engine.
  • 90.TL.R: Titanium case with a vibrant red CVD treated engine.
  • 90.RL.RB (This Review Model): Rose gold and titanium case with a blue CVD treated engine.
  • 90.RL.RG: Rose gold and titanium case with a red CVD treated engine.

Subsequent iterations, such as the HM9 Sapphire Vision (SV) with its entirely transparent sapphire crystal case, and the HM9 Roadster, further expanded the 'Flow' family, each offering distinct material and aesthetic interpretations while retaining the core biomorphic architecture.

The HM9 belongs to MB&F's illustrious Horological Machine series, a lineage of timepieces that includes:

  • MB&F Horological Machine N°1 (the brand's inaugural piece)
  • MB&F Horological Machine N°3 (the 'Frog')
  • MB&F Horological Machine N°6 (the 'Space Pirate')
  • MB&F Horological Machine N°10 (the 'Bulldog')

Beyond the Horological Machines, MB&F also produces the more classically inspired Legacy Machine series, including models like the Legacy Machine N°1, Legacy Machine N°2, and the critically acclaimed Legacy Machine Perpetual.

Other Notable Models by MB&F

MB&F's portfolio is rich with innovative and captivating creations. Beyond the HM and LM series, other notable models include:

  • MB&F Legacy Machine FlyingT: A ladies' timepiece featuring a captivating flying tourbillon.
  • MB&F HM6 Alien Nation: An ultra-limited edition with hand-sculpted alien figures within the movement.
  • MB&F M.A.D.1: A more accessible, yet still highly creative, 'Friends' project.

Similar Watches from Other Brands

While the HM9 is truly unique, certain other independent brands share a similar philosophy of avant-garde design and mechanical innovation:

  • Urwerk UR-105: Urwerk is renowned for its satellite time displays and futuristic designs, appealing to collectors who appreciate unconventional horology.
  • Richard Mille RM 056 Tourbillon Sapphire: Richard Mille epitomizes extreme technicality and innovative material use, often featuring highly skeletonized movements within complex, transparent cases.
  • De Bethune DB28 Kind of Blue: De Bethune is celebrated for its distinctive aesthetic, innovative balance wheels, and exquisite finishing, representing the pinnacle of independent watchmaking.

Homages

Due to its highly complex, patented, and distinctive design, direct homages to the MB&F HM9 'Flow' are not prevalent in the market. The specific three-dimensional architecture and mechanical innovations make it exceptionally difficult to replicate authentically.

Investment Value: A Collector's Dream

The MB&F HM9 'Flow' (ref. 90.RL.RB) was originally retailed with an MSRP of approximately $198,000 USD. In the secondary market, due to its limited production, groundbreaking design, and the immense demand for MB&F's Horological Machines, prices have consistently appreciated. Pre-owned examples typically command prices ranging from $250,000 to over $350,000 USD, depending on condition, provenance, and market dynamics. This trend of appreciation is expected to continue, establishing the HM9 as a robust investment for discerning collectors.

MB&F pieces, especially limited Horological Machines, consistently perform well at major auctions, often exceeding initial retail prices due to their rarity and collector desirability. Specific HM9 auction results vary but generally reflect strong secondary market performance.

Hold Recommendation: Given its limited production, unique design, and the strong demand for MB&F's Horological Machines, the HM9 'Flow' is an exceptional long-term hold for collectors, likely to continue appreciating.

Service Interval and Cost

For a timepiece of such mechanical complexity and precision, a service interval of approximately 4-5 years is recommended. The approximate cost for a full service by an authorized MB&F service center can range from $3,500 USD upwards, depending on the extent of work required. It is imperative that servicing for such a complex, proprietary movement be performed exclusively by MB&F's authorized service centers to ensure its integrity, optimal performance, and to maintain its warranty. Independent watchmakers, no matter how skilled, typically lack the specialized tools, parts, and expertise required for these unique calibers.

Price Range and Verdict for the Sophisticated Collector

Price Range: $250,000-$350,000+

For the sophisticated young collector, the HM9 'Flow' represents not merely a purchase, but an acquisition of a piece of contemporary horological art. Its value lies beyond monetary figures, residing in its groundbreaking design, technical prowess, and the sheer exclusivity it confers. It is a testament to the fact that true luxury is found in rarity, innovation, and an unwavering commitment to artistic and mechanical excellence.

Pros and Cons

  • Pros:
    • Unparalleled three-dimensional horological engine with twin balances and planetary differential.
    • Radical, biomorphic design inspired by aeronautical and automotive aesthetics.
    • Exquisite hand-finishing visible through multiple sapphire crystals.
    • Exceptional wrist presence and conversation-starting appeal.
    • Strong investment potential due to rarity and brand prestige.
  • Cons:
    • Large case dimensions may not suit all wrist sizes.
    • High cost of entry and specialized servicing.
    • Water resistance limited to 30m, restricting active wear.
    • Non-traditional time display requires acclimatization.

Final Verdict

The MB&F Horological Machine N°9 'Flow' is a triumph of imagination and engineering, a timepiece that defies conventional classification. It is a bold statement of individuality and a profound exploration of watchmaking as an art form. For the collector seeking a piece that marries avant-garde design with unparalleled mechanical innovation, the HM9 'Flow' is not just a watch, but a wearable sculpture that pushes the boundaries of what horology can be. Its blend of historical inspiration and futuristic execution solidifies its place as a modern icon, a testament to MB&F's enduring legacy of transforming dreams into tangible, ticking realities.