Cyclo 6-speed came out in 1962, I believe. Shown in Le Cycle. I don't have it in front of me, there is a small chance it could be 61 or 63... and it could be that it was just an improved freewheel, and 6-speed was available before (but as I remember from looking through those years a couple of days ago, it was the "new 6-speed Cyclo").
Before commercial 6-speed freewheels were available, intrepid constructeurs brazed an extra cog onto a 5-speed freewheel for those events where you got extra points for more gears... like the "4 Days of Paris" in 1946 (cf., Vintage Bicycle Quarterly, vol. 2, No. 1, p. 6).
However, most serious riders agreed that 8 on a bike and 10 speeds on
a tandem were enough. Only in the 1950s did triple cranks become
popular among cyclotouristes.
>Admittedly very uncommon, but six speed was available in the late fifties.
>[...]
>Regina had six speed freewheels and also Cyclo I believe.
>
>Chuck Schmidt
>South Pasadena, CA