Simplex rear derailleur vintage bicycle Eroica Peugeot Gitane Mercier

The name Simplex signals a specific period in French drivetrain manufacturing. This rear derailleur is listed under the model names a restorer tends to search for: Peugeot, Gitane, Mercier. It belongs in the Rear Derailleurs category because it is a transmission part. Not trim.

What the Photographs Establish

This is a used component. The images are not a supplement to the listing; they are the primary record of the item's state. Each shot documents the visible condition, so a buyer can assess the cage, pulley wheels, and mounting surfaces before deciding.

Compatibility Context

No clamping diameter or cage length is specified in the source data. Fit must be confirmed against the frame's dropout and the chainring setup. The brand associations in the title — Peugeot, Gitane, Mercier — reflect the French equipment sphere where Simplex parts commonly appear. They are not a guarantee of interchangeability.

For a full drivetrain, a front derailleur also needs to match the seat tube. The Shimano Exage 300 EX front derailleur offers a different era reference. Or, if keeping the cockpit period-correct, a set of SIMPLEX vintage gear shifters would pair logically with this rear mechanism.

Assessment Before Mounting

A used rear derailleur should be checked for pivot play, spring tension, and cage alignment before installation. The photos allow an initial screening. Hands-on verification remains the final step for any component that has already seen service.