see also Holdsworth - Aids to Happy Cycling

1. Date: 1949
   

2. Derailleur brands: Constrictor, Cyclo Gear Company, GB, Huret, Osgear, Resilion, Simplex, TriVelox
   

3. Derailleurs: too many to mention
   

see also Holdsworth - Bike Riders Aids

1. Date: 1975
   

2. Derailleur brands: Campagnolo, Cyclo Gear Company, GB, Huret, Regina, Simplex, Stronglight and Super Champion
   

3. Derailleurs: too many to mention