The most unusual retro-invention.
Family bike with a sewing machine (USA, 1939)
Nogosiped (USA, 1934)
Amphibious bicycle, and you can go on land and on water, the maximum "payload" on the water 120 kg (France, 1932)
Motoloshad useful for learning to ride a horse (Italy, 1933)
Unicycle bike, the maximum speed of 150 km / h (Italy, 1931)