David Ichim, writing for Watches by SJX, takes a deep look at the remontoire system and novel escapement in F.P. Journe's Chronomètre Optimum.
Distilled from Mr Journe’s vision of a perfect chronometer, the watch certainly is meant to be a purist’s timepiece, albeit not a perfect one. The movement performance is perhaps hampered by its own over-engineering and reveals Mr Journe’s predilection for complexity, particularly in the EBHP [high-performance, bi-axial escapement].
Of note, the dual escape wheels and lever in the Chronomètre Optimum are crafted out of titanium, resulting in a lower moment of inertia and less energy draw from the remontoire system.
One aspect of the article I would push back against, unrelated to the Chronomètre Optimum apart from the fact it stands in contrast to the point, is Ichim's sweeping under the rug of Journe's lack of an overcoil in other timepieces in the brand's offerings.
Irrespective of the size of the balance wheel, a hairspring that does not breathe concentrically will have an adverse effect on isochronism. While it is possible to achieve concentricity in a flat hairspring by varying the spring's geometry, as with the Syloxi hairspring from Rolex or the Spiromax from Patek Philippe (both made from silicon), this is not the case when it comes to Journe's flat, wire hairsprings. Coincidentally, Journe has previously dabbled in the production of flat hairsprings that breathe concentrically in partnership with U.S.-based Firehouse Horology and validated the spring's efficacy in a prototype Chronometre Bleu. Unfortunately, in the wake of the global pandemic, Firehouse Horology has ceased operations.
Image via SJX Watches