Hello List,
I also remember Gary Fisher used a similar design on his mid-to-late eighties mountainbikes, exactly like those early bikes.
I asked him about this a few years back, he told me he saw the brazed on steerer tube extensions on early French bikes, and when he was looking to make his higher end fillet brazed bikes like the "procaliber" and "mt tam" lighter, he had them copied, with bolt on stems. Interestingly, Fisher bikes went back to quill stems, and then on to 1 1/4 headsets before setttling on the current threadless "ahead" design, all of which were heavier than his early 1" bikes.
Grant McLean toronto.ca
Jan wrote: Stems clamped onto the steerer tube were very common in the late
1940s. In fact, they used a standard threaded headset. A smaller diameter tube was brazed into the steerer tube, onto which the stem clamped. As Roger Baumann (winner of PBP 1956 and "Pilote de Ren=E9 Herse") pointed out in the interview in VBQ 2, the practice was abandoned because you couldn't adjust the stem height. I have seen Singer, Routens, Herse and others with this feature.