For 1950, the Cyclo Super Olympic and Cyclo Oppy are retired from the 1949 range, and the iconic Cyclo Benelux makes its debut. Confusingly, the Cyclo Ace, which was arguably the least modern gear in that 1949 range, is retained. Perhaps Cyclo had a lot of stock to shift.

To summarise, the 1950 Cyclo derailleur range is:

• The Cyclo Three Speed.
• The Cyclo Four Speed.
• The Cyclo Ace.
• The Cyclo Benelux

• Publisher: Cyclo Gear Company
• Country: UK
• Date: My guess is that 504 means April 1950
• Derailleur brands: Cyclo Gear Company
• Derailleurs: Cyclo Standard, Cyclo Benelux, Cyclo Ace