Falck tubing was still used at least into the 80's. My first 'good' bike (as opposed to the Peugeot that I owned before that) was a Falck-tubed Olympia (the second oldest Italian continuously existing bicycle company). I purchased the bike in 1978 and it was a delightful bike. I readily preferred it to the, twice as expensive, Colnago that I got to replace it.
A number of people opined that the 1970's Legnano that I had for sale at le cirque was made with a special lightweight Falck tubing (no other frame decals are to be found on the bike and it seems quite a bit lighter than most other Legnano bikes.)
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Steven Maasland
Moorestown, NJ