Re: [CR]Magnesium Frame Bikes


Date: Wed, 01 Nov 2006 01:03:27 -0500
From: Joseph Bender-Zanoni <joebz@optonline.net>
Subject: Re: [CR]Magnesium Frame Bikes
In-reply-to: <C58EB0E0-0089-45A1-8931-E365A52F7F2A@earthlink.net>
To: Chuck Schmidt <chuckschmidt@earthlink.net>
References: <JJEEKLDDELHGFDGDBELBKEGPDNAA.avitzur@013.net.il>
cc: Classicrendezvous <classicrendezvous@bikelist.org>
cc: Classicrendezvous

I see magnesium parts now and again in various applications and I am usually very unimpressed. I have been out of the engineering game for ten years what I remember was it had big corrosion problems and little design data. If you can't figure out the effects of stress concentrations, corrosion and fatigue, you basically can't do a design except for some stupid lump like the Kirk. For these reasons and because of fire hazards, Magnesium was forbidden for aerospace designs. Even 7075 aluminium is probably underused in bicycle applications. But corrosion is tricky. I had a seatpost part turn to a chalklike oxide.

Beryllium was allowed for specialty purposes but poisonous in the machine shop. The next step in ultra low density metals would be Lithium. I'm waiting for that.

Joe Bender-Zanoni Great Notch, NJ

Chuck Schmidt wrote:
> Amir Avitzur wrote:
>
>> Anybody ever heard of Magnesium tubed road bikes?
>> Someone mentioned that there was a maker in the UK at one time.
>
>
>
> Kirk Precision... I sold one on eBay about seven or more years ago.
> They were HEAVY DOGS and pretty much a complete failure.
>
> One on eBay recently: Item: 300041223845
> http://cgi.ebay.com/KIRK-PRECISION-CAST-MAGNESIUM-FRAME_W0QQitemZ300041223845QQcmdZViewItem
>
>
> One on First Flight web site:
> http://www.firstflightbikes.com/KirkPrecision.html
>
> Chuck Schmidt
> South Pasadena, Southern California
> United States of America
> http://www.velo-retro.com (reprints, t-shirts & timelines)