Armin Strom has unveiled a special variation of the Gravity Equal Force in partnership Collective Horology, a Silicon Valley-based community of watch enthusiasts founded by tech executives Asher Rapkin and Gabe Reilly in 2018. Collective creates collaborative watches for current members as well as those interested in joining, and the latest watch marks the third collaboration in their Portfolio series, dedicated to showcasing independent watchmaking. Previous editions have included partnerships with J.N. Shapiro, H. Moser & Cie, and Urwerk.

Limited to 30 pieces, the Gravity Equal Force P.03 was inspired by the technical gear associated with Armin Strom and Collective’s shared passion for outdoor exploration. Unusually, the inspiration permeates the entire watch. It not only has a titanium case and khaki fumé dial with luminous numerals and indices – all firsts for the model – but it also incorporates unique treatments to the open-worked movement. The three distinct bridges opposite the offset dial have been treated with ruthenium plating, which creates a contrast against the silver-toned components. Furthermore, the bridges that support the micro-rotor and barrel feature decorative grooves while the third bridge that holds an intermediate setting wheel in place has been milled with a chamfered edge. The base plate has also been black coated, with its left portion decorated with barleycorn guilloché.

In terms of dimensions and physical structure, the P.03 remains identical to the Gravity Equal Force. While Armin Strom’s main claim to fame lies in having developed one of the most reliable and efficient systems for achieving the phenomenon of resonance in a wristwatch, the Gravity Equal Force makes fundamental improvements to the basics of an automatic watch.

It incorporates a motor barrel, a system that was used in American pocket watches originally to protect the gear train from a broken mainspring. With a conventional going barrel, the barrel is stationary as the watch is being wound; the ratchet wheel winds the inner end of the mainspring around the barrel arbour. Conversely, when the watch is running, the ratchet wheel is fixed, and the outer end of the mainspring rotates the barrel, which drives the going train. In a motor barrel, the functions of the barrel and arbour are reversed. The barrel rotates when the watch is being wound but when the watch is running, it remains stationary while the arbour rotates, driving the gear train. Being far smaller than the barrel, the arbour can be better supported by the jewel bearing, reducing wear and ensuring a more precise rotation.

Secondly, the Gravity Equal Force is the first watch that combines a torque regulating mechanism with an automatic winding system. Automatic watches, when worn, are constantly being wound and as such, do not suffer from declining amplitude if the wearer is active. Torque regulating devices are thus more logical when implemented in hand-wound watches.

But in the event that an automatic watch is left dormant, be it over the weekend or because the owner has more than one watch, which is more likely the case in our reality, a stopwork mechanism still comes in handy at ensuring the inferior part of the torque curve is never reached.

However, combining an automatic movement with a traditional Maltese stopwork is not without its own set of challenges as the rotor will still attempt to wind the barrel after it is brought to a halt by the stopwork. As such, Armin Storm has developed a stopwork that is able to decouple itself from the winding mechanism when the watch is fully wound. The stopwork comprises of a finger on the arbour inside the barrel and a wheel shaped like a Maltese cross but with eight concave arms instead of four, followed by a uniquely shaped portion designed to both declutch when the watch fully wound and stop the barrel from unwinding fully, consequently only utilizing a portion of the mainspring where torque is constant. Even though force is restricted by the stopwork, the movement still delivers a power reserve of 72 hours, with a power reserve indicator on the barrel cover for reference.

The watch’s titanium case measures 41 mm in diameter with a thickness of 12.65 mm. By doing away with an in-laid central dial, the numerals and indices are able to be made larger for greater visual clarity and a more balanced design overall. All told, it is fairly unusual to see this degree of customization in a collaborative watch, particularly on the movement itself. Along with its lightweight case and khaki bi-material rubber leather strap, the P.03 delivers quite compellingly, a sporty look and feel while housing a highly sophisticated micro-rotor movement.

Tech Specs

Reference: Gravity Equal Force P.03
Movement: Automatic calibre ASB19, 3.5Hz or 25,200 vph, 72-hour power reserve
Functions: Hours, minutes, small seconds, power reserve
Case: 41mm x 12.63mm; titanium; water-resistant to 30m
Strap: khaki bi-material rubber leather strap
Availability: Limited to 30 pieces
Price: USD 25,000