They brazed a piece of tubing into the steerer, with the OD of the tube being the ID of the steerer (in this case, 22.0 mm). That tube had relatively thick walls, maybe 1.5 or 2 mm. Then the stem clamped onto that. No failures at all, even on tandems. The headset was a standard threaded unit.
Clamp-on stems have got a bad rap for not being adjustable, but if it's a custom bike for an experienced rider, I don't see the need for an adjustable stem. In fact, some of the bikes in the book don't even have adjustable seatposts. That could be a problem if the saddle wears out and the replacement builds taller or shorter...
Regarding Alan's comment on the stems, there are all kinds of custom stems. The Singer stems are even slimmer than a Cinelli. The Herse stem looks clunky in profile, but in real life, you appreciate how sculpted it is, and how little aluminum there is. Despite its beefy sideview, an Herse stem is a bit lighter than an alloy Cinelli stem of the same length...
Jan Heine, Seattle Editor/Publisher Vintage Bicycle Quarterly c/o Il Vecchio Bicycles 140 Lakeside Ave, Ste. C Seattle WA 98122 http://www.vintagebicyclepress.com
>Drooling over Jan Heine's great book The Golden Age of Bicycles I
>noticed that some of these constructors used clamp on head-stems
>over threaded fork steerers.Did they strengthen the steerers or was
>there a high rate of failure at this point ? Clamping a steerer in
>this way over steerers that I have seen does not seem like a very
>good idea given the wall thickness left below the root of the thread.
>Geoff Duke Melbourne Australia