On 12/01/17 03:36, wrote:
On Tuesday, January 10, 2017 at 5:59:05 PM UTC-8, James wrote:
On 11/01/17 01:48, wrote:
A friend who speaks Italian spoke with a bike builder in Italy
who spoke to Ernesto Colnago. He verified that the problem with
Carbon Fiber aside from possible manufacturing defects is that
the resins grow more and more brittle with age. After two years
or so they can grow so brittle that the ultra-lights can fail at
any second. This is why Colnago will only give two year
warranties and why they build their "light" bikes considerably
heavier than other manufacturers.

Have a good ride on your CF when you can get the same weight with
an aluminum frame.


I don't believe age is what causes embrittlement in CFRP, but
exposure to UV light and contaminants that may attack the polymer
probably does.

James, you don't HAVE to believe it. All it means is that the curing
agents in the resins have to have a fairly large amount over the
ideal in order to harden in the time necessary to use on a production
line. And since there is more curing agent than resin it will
continue to cure for a VERY long time afterwards. Some chemists
believe that the curing agent is never "used up" but rather is always
present and hence will continue to harden the resin forever. But
experience has shown that after it reaches a certain point the
hardening slows a great deal.

But that SAME experience is showing that this hardening continues
into embrittlement after long enough. There are NO OTHER resins that
offer the characteristics of epoxy or polyesters.

Though you're free to invent a new chemistry.


Actually, if the resin is not fully cross linked during the
manufacturing process, i.e. there are unlinked covalent chemical bonds
as per your posit, that is what can lead to fatigue failure.

https://cyclingtips.com/2015/08/what...-carbon-frame/

But you are free to imagine other worlds where your dreams are reality.

--
JS