I've read that carbon fiber bars can present problems for bar ends. After swapping my stock bars for the IsoZone bar with integrated grips, I find I'd really like some bar ends to give me a few more choices for hand positions. I've looked at the trekking bars and not found any that really make me interested. I'm perfectly content with spending less for something other than c-f bars, but is there a problem? I'm thinking the GC-3 and I've seen more than a few bars I like - not decided there.

Is it the fragility or the thickness or?

Ergon specifically says this is a big no-no! They go so far as to require reinforcement plugs on thin walled alloy bars. It has to do with the amount of torque that can be applied when GC3s or GP5s are installed vs naked bars.

The solution is to install cheaper bars - which won't be as light, but won't have the same issues. Presumably - if you're installing barends - you're not a weight weenie anyway.