With the new generation of gravel bikes, I was curious if any of them are being made with carbon fiber frames and rack eyelets. Are carbon frames capable of bearing the weight of racks installed on the eyelets?
I have a 2011 Jamis Xenith Endura 2. It is a carbon frame with rack mounts embedded in the frame. I have been commuting with this bike for 5 years, maybe twice a week, most of the year. I also run errands and take recreational with it. I use Ortleib Panniers and often have them loaded up. So far no problems.
I found at least one carbon bike with rear rack eyelets, the Jamis Xenith Endura Elite Di2 Bike but those don't look very strong to me - the eyelet seems to be a separate part moulded into the carbon frame, rather than being part of the dropout. They also use electronic shifting, so you'd need to be able to charge the battery while travelling if you were away for more than a day or two. Since they don't give a weight limit you might be able to get a warranty replacement if it fails. I suggest asking the manufacturer about that before getting too excited about off-road cycle touring on the bike.
If I was building one I'd be more tempted to go for oversize lugs that included the rack eyelets so the force transfer was more contained to the metal parts of the frame. But I don't have any experience of designing carbon frames, only yachts, so I could well be wrong.
Based on my experience with carbon fiber at JPL, if you wanted to have a place to put a load on carbon fiber you would have to make thin sheet metal parts that bond to the carbon fiber part. For example, if I wanted a place to attach a rack to a tube, I would form two titanium sheet parts that are about a half millimeter thick into a question mark shape. The leg of the question mark would have mounting holes and the curved portion would bond to the carbon (assuming you want to connect to a tube). Carbon fiber cannot take point loads like metal so you have to spread the load through a bond over an area. I am not saying you can or should do this, but I am saying this is how you attach to carbon fiber if you want to carry a load. The parts don't have to fit perfectly because the bond takes up fab errors nicely. I would probably pattern the design after those old braze fittings which have the little pointy things sticking out to reduce stress concentration as well. Whatever you do, do not attempt to clamp to a CF tube. That only works with metal