When Simplex do weird, they do weirdly weird.

The Simplex Sélématic is one of the most surreal derailleurs that I have ever seen. It appears to work by a rigid cable pushing or pulling the lever mounted underneath it. This lever springs back to its central position awaiting the next push or pull. Each push or pull activates some mechanism, that I can only dream about, hidden inside the large rectangular body. This mechanism pushes the pulley cage out along a rod. In proper 1950’s style (an age when Simplex ruled the derailleur world) the pulley cage pivot is concentric with both the rod and the guide pulley. Just to complete the 1950’s picture there is a volute spring around the rod mechanism to keep out dirt. Wacky.

US patent # 4,504,250 describes this mechanism in detail with full exploded diagrams - but even after reading this you may be none the wiser.

One of the many mysteries surrounding this design is the issue of chain gap. The design, despite its complexity, makes no attempt to maintain a constant chain gap - so it will probably not work well with a wide ratio freewheel. Another mystery is its weight - it comes in at a stonking 500+ grams - handy if your are cycling in a low gravity environment like, perhaps, the moon.

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I think that this is a surprisingly well-used example of a later Simplex Sélématic 5. Some of its features are:

• The main finish is in a rather utilitarian, milky grey, paint. If you lived in the UK in the 1970s you naturally associate this colour with never-ending hospital corridors, uncomfortable chairs in the waiting rooms of Unemployment Benefit Offices and the acrid stench of those, euphemistically named, Public Conveniences. Oh for the good old days!
• There is no blue line on the outside of the main body, at the joint between two castings.

This derailleur came to me paired with a matching Simplex Sélématic lever in the same institutional grey. This lever is a 6-speed item that has 6 specific positions, clearly labelled 1 to 6. But I have opened up the derailleur and it is a 5-speed mechanism with 5 distinct positions on its control plate. When you want something bafflingly complex - look to Simplex...

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• Derailleur brands: Simplex
• Categories: Simplex - indexing insanity
• Country: France
• Date of introduction: 1982?
• Date of this example: unknown
• Model no.: unknown
• Weight: 522g including hanger plate
• Maximum cog: 36 teeth (Sutherlands 4th edition)
• Total capacity: 38 teeth (Sutherlands 4th edition)
• Pulley centre to centre: 55mm
• Index compatibility: 6 speed
• Chain width: 3/32”
• Logic: nothing meaningful. The derailleur is not big on logic in any way.
• B pivot: unsprung
• P pivot: sprung
• Materials: white metal body, steel pulley cage plates - God knows what materials are inside - Osmium perhaps?

Ref. 2174