Simplex SX810 T/SP

Simplex Prestige LJ derailleur (LJ4000) main image

British consumers never understood the 1970’s Simplex range, and I could never explain it to them. For me, there was the cheap, basic, plastic Prestige at the bottom, and the exotic all-aluminium Super LJ (as used in the Tour de France) at the top - and an incomprehensible jumble of models in between. There was a general idea that the more aluminium parts the better, but this was not always reflected in the price. The model numbers were an object lesson in how to sow confusion in the consumer’s mind.

As for the letters; before the 'slash':

  • CP indicated a racier pulley cage, with less chain wrap -I have been told that the letters may have stood for 'Course Professionnel'
  • T indicated a more 'Touristique' pulley cage, with greater chain wrap
  • GT may stand for 'Grand Tourisme', and indicates a very long pulley cage.

After the 'slash:

  • SP indicated that it fitted directly to the dropout
  • P indicated that it had a built-on hanger plate.

The bizarre doughnut-headed allen key cable clamp bolt is a signature item. Ugly, heavy, and imprecisely manufactured from metal as soft as Camembert - it encapsulates Simplex’s baffling ability to grasp the wrong end of every available stick.

  • Derailleur brands: Simplex
  • Categories: Simplex - the Prestige story
  • Country: France
  • Date of introduction: 1975?
  • Date of this example: unknown
  • Model no.: LJ4000 T/P?
  • Weight: 258g
  • Maximum cog: 30 teeth (Sutherland’s 4th edition)
  • Total capacity: 26 teeth (Sutherland’s 4th edition)
  • Pulley centre to centre: 45mm
  • Index compatibility: friction
  • Chain width: 3/32”
  • Logic: top normal
  • B pivot: sprung
  • P pivot: sprung
  • Materials: aluminium rear knuckle, plastic front knuckle, plastic and steel parallelogram plates and steel pulley cage plates.
Simplex Prestige LJ derailleur (LJ4000) additional image 01