Richard Mille Introduces the Ultra-Lightweight RM 55-01 Watch
Simplified Structure and Composite Materials
Unlike previous horological extravaganzas, Richard Mille recently released the RM 55-01 watch, a timepiece that displays only the time. The RM 55-01’s movement emphasizes a simplified structure and lightweight design, a restrained manual-winding timepiece weighing less than 5 grams—equivalent to the weight of a sheet of A4 paper.
When Richard Mille first debuted in the early 2000s, it essentially launched a niche market of ultra-expensive “super” sports watches, and has since refined its approach, skillfully blending complications, materials, and bold aesthetics to create an extremely expensive yet lightweight and ergonomically designed combination.
The RM 55-01 watch marks a return to Richard Mille’s roots, featuring an extremely lightweight movement that forgoes automatic winding and any complications. This watch displays only hours, minutes, and seconds—a rarity among Richard Mille watches today.
The RM 55-01 feels like a spiritual successor to the discontinued RM 55 “Baba Watson” watch. The case lines and movement itself are remarkably similar to that model, although the RM 55 was primarily positioned as a lightweight and robust golf replica watch. The new RM 55-01, however, aims for extreme lightweight design.
Lightweight Architecture
The RM 55-01’s design philosophy is openness and transparency. The heavy case resembles an aquarium, with the movement seemingly floating within. The colorful bezel and case back outline the watch’s silhouette, each color scheme showcasing a unique personality.
The RM 55-01 is initially launched in three color options: White Quartz TPT, Grey Quartz TPT, and Carbon Black TPT. The name “Grey” is somewhat misleading, as the watch is actually a soft blue and cannot be considered grey at all. While all three color schemes are quite simple, I personally prefer the grey quartz TPT colorway.
The bezel and case back use TPT composite material from the Swiss manufacturer North Thin Ply; TPT stands for Thin Ply Technology. Unlike composite materials commonly used in watchmaking, this special composite material has a rough, layered texture, reflecting Richard Mille’s more sophisticated materials science practices. The aerospace-grade minimalist design of the titanium inner case complements the composite material components perfectly.
The RM 55-01 is powered by the RMUL4 movement, with “UL” standing for “Ultra Light.” Aside from minor differences in surface finishes and slight external modifications to the internal workings, the RMUL4’s structure is essentially the same as the RMUL2 movement used in the Bubba Watson RM 055 watch.
In terms of surface finishes, the RMUL4 maintains Richard Mille’s consistent high-tech industrial style. The Grade 5 titanium bridges are treated with Titalyt and coated with PVD. The spline screws are a patented Richard Mille design, capable of withstanding various torques. These screws are virtually unaffected by physical handling, thus maintaining excellent performance even after repeated use.
The movement is streamlined to its most basic elements—the mainspring barrel, the gear train, and the balance wheel. The overall construction is simple yet high-quality, featuring a 4Hz free-oscillating balance wheel and two series-connected mainspring barrels.
The RMUL4 movement offers only 55 hours of power reserve, indicating a high mainspring barrel speed. This design aims for a more stable torque delivery during the power reserve, while avoiding excessive torque on the gear train. The legendary Longines L.990 series and many modern Omega Co-Axial movements also employ the same principle. whereguidewatch.com
Richard Mille RM 55-01
Case Diameter: 37.95 mm x 47.33 mm;
Thickness: 10.75 mm;
Material: Quartz TPT or Carbon Fiber TPT;
Crystal: Sapphire Crystal;
Water Resistance: 50 meters
Movement: RMUL4
Functions: Hours, Minutes, Seconds
Winding Method: Manual Winding
Frequency: 28,800 vibrations per hour (4 Hz)
Power Reserve: 55 hours
Strap: Textile with folding clasp