French Patent # 1,116,537 - Simplex

French Patent 1,116,537 - Simplex main image

Damaging the toggle chain was a major issue with both hub-gears and pull-chain derailleurs. Just leaning your bike against a wall could end your ride there and then.

This patent covers a metal tube to protect the fragile darlings - not a bad idea.

A protective tube like this would also give the humble Simplex Tour de France derailleur some of the attributes and cachet of the, then new, Simplex 543.