This 1951 patent, and its older brother, French Patent # 1,036,415, are startlingly contemporary.

Just looking at this innocent image, I can feel a creeping dread that the adjuster will be solidly rusted in place - and will gleefully snap the moment I touch it - setting in train some kind of horrendous drama involving a tiny drill bit which will, of course, keep the party alive by also snapping, and an M3 X 0.5 tap - which will join the fun by committing harakiri - leaving an undrillable-tool-steel-remnant jammed in place etc. etc... Oh joy!

• Publisher: L’Institut national de la propriété industrielle
• Inventor: Tullio Campagnolo
• Country: France
• Date: Italian application June 1951, French application July 1951
• Derailleur brands: Campagnolo
• Derailleurs: none - or possibly nearly every single one!