4

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?

  • 2
    Carbon fiber is used to build transmission housings for Formula 1 cars. 700+ HP is sent through the tranny and part of the rear suspension is bolted to the transmission. Carbon fiber can take the weight of a few racks, it's a matter of are they being designed to. – FreeMan Jun 14 '16 at 14:02
5

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.

|improve this answer|||||
2

I would not call it gravel bike but more adventure bikes

We are seeing eyelets in carbon forks
firestarter Hard to tell but that is a carbon fork
enter image description here

A rear rack would require a bigger seat stay. I think they could but it just does not made that much sense. If you want to carry a load then go steel or titanium.

|improve this answer|||||
1

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.

enter image description here

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.

|improve this answer|||||
  • Are you sure that wasn't intended to be a fender eyelet only, rather than a rack eyelet? – Rider_X Jun 14 '16 at 19:35
  • @Rider_X quite possibly, but there's no exclusion or weight limit specified so at least in Anglonesia you'd have a fairly solid warranty claim. roadbikereview says "hidden fender and carrier mounts are stock on the frame" which suggests that if I'm wrong it's an easy mistake to make. Richard's answer above refers to an earlier model of the same bike and that one hasn't broken (yet) – Móż Jun 15 '16 at 0:48
0

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

|improve this answer|||||

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.