Some models find their highest expression in extreme sobriety, concentrating all the craft of contemporary haute horlogerie into an architecture reduced to its essential mechanical necessity. The new RM 55-01 manual winding fully embodies this approach, showcasing a decidedly open structure in which every component is perfectly positioned according to its function.
With the new RMUL4 ultra-light calibre, the model takes one of the brand's founding principles to new levels through an exceptionally high degree of skeletonisation. Weighing less than 5 grams, the movement has been carefully designed to integrate into a case of conservative dimensions (37.95 x 10.75 x 47.33 mm), while optimising both wrist comfort and visual balance. The choice of manual winding meets the clear demand for lightness: without the obstacle of the rotor, light and gaze flow freely through the movement.
The movement rests on a grade 5 titanium baseplate, an alloy borrowed from the aerospace industry, micro-blasted, polished and treated with a black PVD coating. The gear train is secured by three bridges also in grade 5 titanium, polished with Titalyt® surface treatment. Machining this material remains a constant challenge: its extreme hardness and low tolerance for error put every tool to the test. The same rigorous standards apply to the slightly thicker satin-finished parts that structure the movement and emphasise the contrast between straight and curved lines.
The heart of the mechanism is a twin barrel system that optimises the storage and distribution of torque over time. Thanks to the higher rotation speed, teeth, pivots and bearings are subject to a lower load, reducing friction and ensuring a smoother, more consistent energy transfer throughout the approximately 55 hours of power reserve. The energy is transferred to a variable inertia balance wheel operating at a frequency of 4 Hz (28,800 vph), fitted with a seconds-stop mechanism. The traditional regulating lever is replaced by four small adjustable weights on the balance ring, allowing for more precise and consistent regulation that acts on the inertia of the balance wheel rather than the effective length of the hairspring, making it less vulnerable to shocks.
Three versions of the model are available: Carbon TPT, white Quartz TPT and grey Quartz TPT. These technical composite materials, used for the bezel and caseback, offer excellent resistance to shocks and scratches while reducing the overall weight of the watch. The raw damascene effect of the materials harmonises with the taut, clean lines of the three-part tonneau case. Four micro-blasted titanium slotted screws firmly anchor the movement to the case, framed by the characteristic satin-finished half-columns and polished bezels. The micro-blasted and rhodium-plated hands sweep across a complex four-part inner bezel that weaves together titanium, carbon fibre and steel in an interplay of textures and relief.
On the wrist, the RM 55-01 manual winding exudes a subtle sobriety, yet up close it reveals a captivating mechanical presence. Suspended between silence and tension, the watch embodies an inner odyssey — that of time laid bare: never empty, the space becomes the very place where time is born, immune to gravity.