NOS SIMPLEX GOLD SUPER LJ SLJ PX PY Front Derailleur 10-Speed Mercier Gitane DV13

The Simplex Gold Super LJ: a French derailleur that refuses to age

Simplex built its reputation on derailleurs that shifted cleanly when other systems hesitated. The Gold Super LJ SLJ PX PY carries that engineering intent. This is a new old stock unit,, still in its original state. The steel and aluminium construction keeps the weight honest and the action precise, exactly as it left the French workshop. The 10-speed designation places it firmly in the era of steel frames and friction levers, where feel counted more than indexed clicks. The "Les photos font partie de la description" principle applies here: the visual record is part of the listing, and it should be read alongside the text.

What the DV13 code and the PX PY designation tell you

The Simplex catalogue used letter combinations to denote specification tiers, and the PX PY marking on this derailleur identifies its place within the Gold Super LJ family. For anyone running a Mercier or Gitane frame from the same period, this is the correct companion piece. The straightforward steel and aluminium build means there is nothing fragile hidden inside.

New old stock: what it means in practice

NOS means the part was. The 10-speed specification is stated on the listing. No oxidation is reported. Cosmetic traces or micro-scratches related to long storage may exist, as with any vintage part held for decades, and these are visible in the photos that accompany this listing. If you are building a period-correct machine, the surfaces and finishes should be checked against the images before purchase.

Key specifications

Technical details

• Country of origin: FRANCE
• Oxidation: No
• Material: Steel/Aluminium
• Manufacturer part number: 0000
• Speed: 10-speed (as stated in the product name)
• Model designation: Gold Super LJ SLJ PX PY
• Condition: New old stock (NOS)

Pairing and context

The Simplex Gold Super LJ sits naturally alongside other French drivetrain components. If you are working on a Mercier or Gitane build and need a compatible rear derailleur family, the [Simplex Gold Super LJ rear derailleur](https://streetofvintagebike.com/gb/derailleurs-avant/3721-derailleur-avant-le-simplex-suicide-sgdg-vintage-bike-1948-rare-f01.html) lineage is worth understanding before you commit to a groupset. For a broader selection of period front derailleurs, the [front derailleurs category](https://streetofvintagebike.com/gb/147-wheels) may offer alternatives if you are weighing options. And for those restoring a complete French machine, the [BIANCHI NTH 520 wheelset with Campagnolo 8-speed hubs](https://streetofvintagebike.com/gb/wheels/4356-copy-of-copy-of-cadre-velo-mercier-full-reynolds-531-2345g-5757-994-1266-mm-bfff-f10.html) shows how a build can come together when the right components appear.