SIMPLEX SX610 Long Cage Rear Derailleur - Vintage Bicycle Part DAR13

The SX610’s long cage design increases chain wrap capacity, a practical asset when running a wide-range freewheel or a triple chainset on a period build. This SIMPLEX unit comes from the era when derailleurs were still serviceable mechanical objects, and its steel and aluminium construction reflects that approach.

What the Long Cage Changes

A longer cage lets the derailleur absorb more chain slack. That means the SX610 can hold a larger total tooth difference without losing tension. For restorers fitting a wide-ratio block, this is often the difference between a clean shift and a chain that droops in the small-small combination.

Key Specifications

• Material: Steel/Aluminium
• Manufacturer part number: 0000
• Country of origin: France

This is a used component. The photos are part of the description; minor cosmetic marks and light surface wear from storage may be present. Examine the images closely for the exact condition of the pivots, cage plates, and mounting bolt.

If you are comparing cage lengths, the SIMPLEX SX410 rear derailleur long cage vintage PEUGEOT offers another long-cage option from the same lineage. For a different era of SIMPLEX engineering, see the Simplex Juy 61 Export Vintage Rear Derailleur.