[CR]Vintage Bikes, Vintage Skis, why the difference? It's the economy ....

(Example: Component Manufacturers:Cinelli)

Date: Sun, 16 Mar 2008 14:57:19 +0100 (CET)
From: "Nick March" <nicbordeaux@yahoo.fr>
Subject: [CR]Vintage Bikes, Vintage Skis, why the difference? It's the economy ....
To: classicrendezvous@bikelist.org

Another mad note from the nut from France: carbon fiber whatever it's intrensic strength, modulus of what you wish for a given weight is an unsafe, undurable material. I have extensive experience in the fishing rod industry, and I can tell you that CF does not take crush or hit. One unoticed hit from a stone breaking a fiber in it will produce weakness, the fiber next to it will go, and so on exponentially. Until it's snap time. Look at the number of dents and knocks you'll find on an old steelie. On carbon, those will lead to failure somewhere down the road. Inevitably, no maybes in that one I'm afraid.

CF tubing will take effort vertically, lateraly, whatever. It will not take torsion. It also crushes easily on local pressure application. Both of these aforementioned cause have an effect visible as multiple vertical split. I can think of more dignified ways of doing rectal Hara kari than riding a carbon seatpost 8 inches out of the frame (please do not inquire, I shall not elaborate).

For those of you with carbon crush failure, I know of only one remedy: balsa insert, and overwrap with cotton binding thread (Gudebrod is a good supplier), cellulise varnish to tighten, then marine varnish. Whilst you are at it, I think you might as well bind a few Fuji rings to it, and use it as a fishing rod when needed.

Last point: carbon fiber is carbon fibers (capital S on that plural) in a medium of "glue". A chain is only as strong as it's weakest link. You don't need to be an engineer to work out what that means.

Nick March, Agen, Lot-et-Garonne, France

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