The variable-slant-parallelogram of the 1987 Campagnolo Chorus is described in loving detail in this patent. Unsurprisingly, no mention is made of Boris Rostislavovich Mikhailov's curiously similar Soviet patent dating from 1979.

• Publisher: L’Institut national de la propriété industrielle
• Inventor: Tullio Campagnolo
• Country: France
• Date: Italian application January 1987, French application January 1988
• Derailleur brands: Campagnolo
• Derailleurs: Campagnolo Chorus (C010-SM), Campagnolo Chorus (C010-LG)