T-Mar

Thank-you for the contributions.

The bicycles are 1975 and 1978 models respectively. In the late 1970s, double butted hi-tensile was often found on upper, entry level models. Tange had two such sets and Ishiwata had a least one. It appears to have been used primarily in Japanese brands. In addition to Fuji, I've seen similar tubesets on Miyata and Sekai. It faded from use in the very early 1980s and, at least in Fuji's case, appears to have been replaced by VaLite.

Being made of hi-tensile steel,these tubesets were obviously thicker and heavier than butted CrMo or MnMo tubesets. They were also heavier than plain gauge CrMo of the era but bridged the gap between plain gauge hi-tensile steel and plain gauge CrMo in weight and apparently, cost.