Joined: Nov 2006
Posts: 19,810
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From: NJ, NYC, LI
Bikes: 1940s Fothergill, 1959 Allegro Special, 1963? Claud Butler Olympic Sprint, Lambert 'Clubman', 1974 Fuji "the Ace", 1976 Holdsworth 650b conversion rando bike, 1983 Trek 720 tourer, 1984 Counterpoint Opus II, 1993 Basso Gap, 2010 Downtube 8h, and...
I've seen them called "spearpoint stem" or "lugged stem," but I'm not sure either term is widely used enough to be worth remembering.
They first appear in the 40's or so. Reynolds made one of that basic type, cast in aluminum. They are really modeled on hand-made stems brazed up from steel tubing; GB made them from both Reynolds 531 and Accles&Pollock Kromo tubing; and then, in the 50's, GB made a cast aluminum (hiduminium, actually) version that was based on the steel ones. Most aluminum stems from the 50's through to the early 70's were more or less of this style; brand names I've seen on them include GB, Reynolds, Pivo, AVA, Philippe, Compe, Jun, and... oh, I don't know, there were a lot of them.
Lugged stems, in a style similar to what you showed, but made for threadless type forks, are made today; they're steel, handmade, and expensive.