This is an extraordinary derailleur design. There is no pivot in the rear knuckle (it is rigidly set in position), the parallelogram looks to be angled in the opposite direction to the one you would expect (and which everyone else uses) and the sci-fi style pulley cage plates would make Dan Dare proud.

Unfortunately I have never seen an example of this fine item - if, indeed, one ever existed.

---

• Publisher: Urząd Patentowy Rzeczypospolitej Polskiej
• Inventor: Jerzy Steinborn, Witold Łoś, Jósef Kamiński & Lech Herman
• Country: Poland
• Date: Polish application March 1981
• Derailleur brands: Romet
• Derailleurs: unknown