Re: [CR] Inventment cast one piece headtube and lugs


Example: Production Builders

In-Reply-To: <4D3E2FB5.9020706@ody.ca>
References: <435884.71607.qm@web161206.mail.bf1.yahoo.com>
Date: Mon, 24 Jan 2011 21:50:17 -0600
To: classicrendezvous@bikelist.org
From: Mark Stonich <mark@bikesmithdesign.com>
Subject: Re: [CR] Inventment cast one piece headtube and lugs


At 9:04 PM -0500 1/24/11, Marcus Coles wrote:
>It wasn't just a Trek thing, I have a couple of Jim Miele "Bianchi"
>bikes from around the same time frame with one piece head tubes with
>false lugs.
>I believe these bikes were sourced in Japan.

I first saw these on small Sekai road bikes in about '76.

The problem was that in order to take that much forming they had to be made from relatively soft metal. And the headset bearings on a small frame are close together so there was a lot of leverage on them. Small road frames were usually ridden by small people. So while there were a few failures they could generally get away with it. But then Trek and (and I suppose others) used them on MTB frames. Larger riders for a given frame size, shallower head angles and more abuse led to lots of bellmouthed "head tubes".

Many years ago I came into possession of a small '83 Trek 850 frame. Tange Champion tubing, 48.5mm chainstays and a bellmouthed HT. This fall I was looking for the basis for a good winter bike. For winter I want high bars but a low top tube so an HT transplant sounded like a good idea. The tube ends were not mitered and for a winter beater, KOF level work isn't needed. So I just cut off the front of the "HT" and spread the remaining half wide enough to accept a much longer Columbus HT. Spreading it wider took depressingly little force. http://bikesmithdesign.com/MyBikes/snowmobile/new-ht.jpg

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Mark Stonich;
     BikeSmith Design & Fabrication
       5349 Elliot Ave S. Minneapolis, Minnesota 55417 USA
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