Simplex Super LJ SLJ Rear Derailleur for PX10 PY10 Mercier DAR10

The Right Rear Derailleur for a 1970s Build

Achieving a smooth-shifting, period-correct drivetrain on a 1970s ten-speed starts with the rear derailleur. This Simplex SLJ variant delivers the exact blend of lightness and reliability that defined the era. At just 225 grams, it keeps weight low without compromising the precise chain management that made the Super LJ series a mainstay on top-tier road machines.

Why This Mech Works for Your Project

The SLJ’s geometry and short cage are tuned for the close-ratio freewheels typical of racing and sportive ten-speeds. It suits Peugeot PX10, PY10, Mercier, Gitane and many other frames that use a standard derailleur hanger—no special adapters needed. The steel and alloy construction balances resilience with light weight, exactly what you want in a restoration-driven drivetrain.

If your setup calls for a wider gear spread, the Simplex Super LJ SLJ 5500 long-cage variant is also in stock. We also offer another SLJ unit from the same family, so you can compare condition and provenance.

Technical Characteristics

• Weight (in g): 225g
• Matter: Acier/Aluminium
• Numéro de pièce fabricant: 0000
• Pays d’origine: FRANCE

Condition & What You See

This is a pre‑owned component. Please note that the photographs form an integral part of the description; they illustrate the exact unit you will receive. As with any vintage part, expect minor cosmetic marks consistent with age and storage. No major defects—such as rust, cracks or bent parts—are reported.