It started with the trusty 10 speed...
3-speed, 1902; 2-speed, 1882.
It looks like a gearbox where the bottom bracket would normally be. Is this the new thing?
Since the mid-1890s. Adler in the 1930s was probably the most successful.
Automatic with constant velocity shifting. Smoooooth with no actual gears.
Enviolo Automatiq.