There is a fellow who is selling three NOS Carrera Columbus frames and forks on Swiss Ebay. I asked the seller about the sizes and he sent me the following information:
The red and purple ones are both 55 cm c/c or 56.5 cm c/t with a 55.5 cm top tube The green one is 56 cm c/c or 57.5 cm c/t and he did not indicate the top tube length to me.
The Carrera frames are generally quite nice. I am not sure of the exact production date but I would guess from the 80's.
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Steven Maasland
Moorestown, NJ