Originally Posted by
PinarelloMadcat
I had severe scoring on the resin of my carbon fiber cage on my 2008 Campy Record front derailleur from chain shifts and had it replaced once, but it happened again soon afterward. Fearing that I could have a similar problem of an enventual failure I replaced the carbon cage to an aluminum cage that comes with Chorus. I think that using carbon fiber for any use that involves frictional contact is a big mistake. Carbon fiber resin simply is not strong and cannot withstand this type of use. I wouldn't be surprised if Campy changes the Record cage material back to aluminum or titanium in 2009.
When will the carbon fiber-can-do-no-wrong madness end? (I know alot of bikers who are going back to aluminum wheels after having failures with their carbon fiber wheelsets.)
I don't know if it's fair to say that CF shouldn't be used on a front derailleur because of the problems that you've experienced.. I've had no such scoring or problems of any kind on my derailleur.
The job of the front derailleur is to gently push the chain off a chainring. It doesn't take much force at all. Once the chain drops the chain should be within the width of the cage, minus certain combinations with the cogs in the back.
The OP probably didn't have something adjusted correctly or who knows. I highly doubt that this is a widespread issue.