The Simplex Champion de France 35 is, at once, a crazy-looking, fever-dream of a derailleur and a surprising trendsetter in derailleur design.

Sure, that highly styled, bronze, pulley cage jutting out in front is bizarre. Sure, the lever-bolt holding the pulley cage in place is beyond odd.

But this is also the earliest derailleur, that I can recall, that that had an identifiably modern hanger plate. It is also one of the first that had a small, untoothed, pulley wheel that is of a size that came to be seen as normal. Up to this point most derailleurs had large toothed guide pulleys. Finally this is one of the few derailleurs to have a chain tension spring that was completely built in - as it is in modern derailleurs.

Originally this derailleur had a long loop for the fixing bolt at the hanger plate. Unfortunately, someone who has owned this derailleur has viciously hacked off a large part of this loop. Perhaps this person actually wanted to use this derailleur on the road - rather than preserving it for posterity. So it goes.

• Derailleur brands: Simplex
• Categories: Simplex - before 1945
• Country: France
• Date of introduction: early 1935
• Date of this example: unknown
• Model no.: unknown
• Weight: 222g including not quite all of the hanger plate
• Maximum cog: 22 teeth?
• Total capacity: '4 to 5 teeth'
• Pulley centre to centre: not applicable
• Index compatibility: friction
• Chain width: 1/8”?
• Logic: low normal
• B pivot: sprung
• P pivot: none
• Materials: steel with a bronze chain guide around the guide pulley

Ref. 1870