[CR]Herse stems - how made?

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To: classicrendezvous@bikelist.org
From: "Jan Heine" <heine@mindspring.com>
Subject: [CR]Herse stems - how made?
Date: Sat, 14 Dec 2002 14:26:59 -0800

Looking through New Cycling's Rene Herse book, and contemplating the Herse tandem at Il Vecchio's in Seattle, I wonder how the stems are made.

On page 105 of the Herse book, the photos show a long bar of aluminum with holes drilled in strategic places. It is obvious how they will be cut into stems and then filed until the final shape is achieved.

What puzzles me is the alloy tube inserted where the handlebars will go. Clearly, the aluminum bar has been filed smooth in these places, and an alloy tube has been inserted. This tube forms the little raised lip that surrounds the handlebars on every Herse stem I have seen (compare photo on p. 104).

What puzzles me is the purpose of the tube. There is extremely little material above and below the tube. And since the tube will be slotted for the clamp, it doesn't do anything other than being a spacer - as if the stem was made for an oversize bar.

Why not simply drill a smaller hole for the bars and do away with the raised lip? Also, since the inserted tube does not move, how is it attached? (Pressing in wouldn't work, because the perimeter is slotted for the clamp.) Welded in place? Bonded?

Considering that Herse stems don't break, and that Herse knew what he was doing, and did these the same way for about 50 years, it must make sense. I just don't understand.

Any ideas?

Jan Heine, Seattle