Someone on the list was (I believe) trying to catalog GB stems...the thread was a few months ago. Anyway, in building an early-70's Schwinn Super Sport I noticed that its original stem (with 'S" logo) was exactly like one of my GB stems. Since the randonneur bars are marked "GB", I'll bet the stem is GB too. Now I wonder if the earlier stem of these models, the one with flat-top and T-cross-section, may not have also been made by GB? Of interest is this flat-top stem doesn't seem to appear on any other bikes unless someone else knows better. I suppose Schwinn could have made it but I would doubt it.
Jack Romans
Sacramento