I know a lot of us have friends that own or work in bicycle shops. At my size I have been consistently warned away from both aluminum and carbon fiber bicycles. The friends I know all said the same thing. They break too often. I have thus stayed with steel which is not as strong as carbon and much heavier, but generally has a gentler failure mode. Steel bicycle components fail too, but I believe at a much lower rate that the aluminum/carbon bicycles. The way steel is made into piping gets rid of air pockets and reliably homogenizes the material into just steel and no voids. Carbon fiber is basically cast and this has a much higher rate of getting air pockets and is a hard problem to deal with. Ultrasonic testing can cull out the bad carbon components but I'm not sure manufacturers are doing this on new components. It is costly to perform the tests. I believe carbon fiber is in its infancy for bicycle manufacturing and if it persists into the future these problems will be solved. Carbon fiber is a wonderful material. Wsteve464's link to the Linn article is eye opening. The carbon fork manufacturer Deda states that: From Deda:
Carbon lasts longer than metal.Only love is stronger than carbon.Bonding is a different story.I believe that a good glue (epoxy) can last for 2000 hours of work, or about 800 days, not in continuous daylight, and below 35 Celsius.Whenever a carbon “part” has crashed, even if you cannot see a failure, if there is any reasonable doubt about having surpassed the elongation limit, the part must be replaced.
–Fulvio Acquati
So when talking about carbon fiber forks we are talking about two materials if not more involved in the manufacture of the fork. As Mr. Acquati points out the epoxy resin has a much more limited strength and longevity than carbon fiber. I've used a lot of epoxy resin and it has to be protected from the sun. It is not an especially hard material and is easily dented, cut or otherwise defaced on its own. This manufacturer wants a limit on the amount of time spent working before they want their product replaced. I believe this all fits into the early days narrative for carbon fiber. This will probably get much better as time goes on. As of now there is still a whiff of we are the guinea pigs in the carbon fiber experiment. There is very little transparency in the bicycle business so it is hard to get a handle on failure rates for any material. Steel has a long history of successful bicycles and is very well understood. Carbon is still being developed. Good luck with your carbon fiber components.