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Vintage Components - Simplex rear derailleurs

Simplex rear derailleurs on this page: Super LJ 5000 short-cage gold-anodized | SX610-Peugeot | SJ810-GT - Peugeot | Alpha T

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Simplex founder Lucien Juy owned a bike shop in Dijon, France, when he began making his first derailleurs in 1928. His innovative designs were a hit and by 1933, Juy said he was making 40,000 derailleurs a year.

It wasn't until 1961 that Simplex adopted the deforming parallelogram that Campagnolo had popularized with its ground-breaking Grand Sport derailleur a decade before. But Juy's Simplex derailleurs had a sprung top pivot, the way all derailleurs are made today. At the time, that Simplex Export 61 was probably the best-shifting changer made.

A year later Juy decided to make Simplex derailleurs out of an acetal resin (OK, plastic) made by Dupont called "Delrin". It was a terrible mistake. Juy took what was the best derailleur in the world and turned it into a flimsy, delicate changer.

In the early 1970s Juy again began producing superb changers when he came out with the alloy Super LJ series. They were nicely finished, well-designed, good shifting derailleurs.

No amount of innovation or quality improvement could stem the Asian onslaught, exacerbated by association with those delrin derailleurs that came on so many bike-boom bikes. Simplex ceased production in the 1990s.


Simplex Super LJ 5000 short-cage rear derailleur, gold anodized. lightly used, $250.00

Simplex made continual refinements to this superb derailleur. This is the second version of the SLJ 5000, produced in 1977 and 1978.

Simplex Super LJ

Wonderful condition, rare gold anodization

Simplez Super LJ

From the back


Simplex SX610 - Peugeot rear derailleur. Used, $65.00/each

  • This is version two of the SX610
  • Produced 1983 - 1985
  • Will throw up up a 28-tooth cog
  • This derailleur was also sold as a Spidel and Gipiemme Crono Sprint rear derailleur
  • Simplex regularly branded their derailleurs "Peugeot" for the bicycle company that must have been their largest customer.

Simplex SX610 rear derailleur

Version two of this deraileur can be spotted by the ribbed derailleur body.

Simplex SX610 rear derailleur

The ribbing is more easily seen here.

Simplex SX610 rear derailleur

The back, showing the Delrin/steel part of the derailleur body.

Simplez SX 610 rear derailleur

Close-up of the moving parts

Simplex SX610 rear derailleur

From underneath


Simplex SJ810 GT - Peugeot rear derailleur. Used, $45.00/each

  • Produced 1977 - 1985
  • Simplex regularly branded their derailleurs "Peugeot" for the bicycle company that must have been their largest customer.
  • This derailleur will handle a 36-tooth cog.

Simnplex SJ810 rear derailleur

Made with both Simplex and Peugeot logos.

Simplex SJ810 rear derailleur

From behind

Simplex SJ810 rear derailleur

The back of the derailleur. Note the long cage to handle wide-range gearing.

Simpplex SJ810 rear derailleur

Front view

Simplex SJ810 rear derailleur

From the top.

Simplex SJ810

Parts of the derailleur are made of Delrin plastic. Here's the back part of the parallelogram made of Delrin sandwiched between to steel plates.


Simplex Alpha T rear derailleur, Version 2. Used, $40.00

Part# 75305

  • The Alpha was made in the early 1990s, making it one of the last derailleurs Simplex produced.
  • This derailleur is made of Delrin & steel. The top and bottom pivot parts are Delrin and the rest appears to be steel.
  • Simplex kept fussing with the Alpha derailleur design. There appear to be four versions of which this is the second.

Simplex Apha T rearderailleur

Not very many of these derailleurs left.

Simlpex Alpha T rear derailleur

And from the back