Custom Carbon Fiber

General Discussion
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Hi all! Anyone else out there doing carbon fiber? I thought I’d try to kick off a thread and see who is doing what and how. Tube to Tube, modular monocoque, tube and lug? Why did you choose the method you did, how do you design and make your tools, and how do you design your laminate and ply shapes?

Unlike metal bikes, carbon construction seems to be very secretive. Nobody wants to share much because it’s so costly to get the info in the first place. I’ll admit we won’t give away the farm, but I’ll help where I can.

Another big challenge is the raw material. There aren’t a lot of options - outside of tubes - available off the shelf. What stays and dropouts do you use? Do you make them yourself, do you make your own tubes, or for that matter make your own molds, etc.

If you don’t do carbon, but are thinking about it, what’s stopping you?

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Carbon intrigues me but I’m so invested in steel at the moment. Im interested from a race perspective on say road and xc for the weight perspective, but I also think that is a little overplayed for the club level racing.

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I worked at Alchemy back in the day mitering and tacking all the frames together. Nothing better than mitering carbon. Zzzzzooop!

A couple of years later I went to Bohemian to learn the process with Dave. Never really intended to pursue it, I just like to learn as much as possible.

Now I got some Ti cut-offs begging to be turned into a Ti / Carbon frame for my own satisfaction.

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I would love to dive into carbon. But the investment is the biggest issue.

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I don’t think the investment is that high for tube to tube. There is enough information to buy the tubes, joing tow and cloth and resin so their wouldn’t be any tiral and error there. A jig, curing oven and vaccum pump. Capital cost is not that high really. Curing oven can be made with easy to get materials and parts. The real learning is how to lay the tow and cloth in a tube to tube method or you could do metal hard points and glue together.

I am probably over simplifying a few steps, I’m sure.

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A layup schedule for tube to tube would be helpful for some diy garage experimentation.

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When I started building with carbon, I purchased the tubes and stays from Enve. I made aluminum dropouts. Other than that I bought a vacuum pump from eBay for $100, and made an oven using an element from a $20 garage sale oven and a PID controller that was about $100. Once you add in the supplies; bag, release, breather and plumbing, I was into it for about $1000. Most of the other tools are the same tools you use for metal bikes.

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Layup schedules are the secret sauce for most builders. But if you want to keep it simple, and you should in the beginning, start with a quasi-isotropic layup

That is a nice safe way to go, allowing you to focus on the actual work of making the bikes. As you get familiar with the fabrication requirements, you can start to focus on more complex layups. Once you get to that point, thinking about the job each individual tube has to do, the variation on the layup becomes more apparent.

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This is great info. Will Enve sell tube to any Joe Shmoe like myself? You have a more recognizable and respected name in the bike building world and totally understandable.

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No, the no longer sell tubing. They sold all the stuff to a guy who is in the SLC area, but unfortunately I don’t know the business name. I’ll see what I can find.

For tubing now, your best source is probably Rock West Composites, also in the SLC area. They are part of what was McClean Quality Composites whom for while owned Reynolds Composites.

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Thanks for the info. What tubing size and wall thickness would be used?

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That is frame design, and I can’t advise on that.

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@Pursuit Thanks for starting this discussion!

That is a great point. I honestly think for frame building as a hobby, carbon fiber bikes are the lowest barrier into the craft:

  • no large machine tools
  • no large space requirements
  • no dealing with gasses and flames

I can see a world where in 5-10 years, carbon fiber frame building is the norm, not because of performance characteristics, but because it has the smallest space constraints to get into it.

I have played around with composites before, but never on a bike. This is something that I am eventually going to get to in the next year or two.

From my naive perspective, the current barriers to carbon building are:

  • lack of knowledge
  • lack of “carbon weldmets”: dropouts, BB’s, headtubes, etc…

Imagine if paragon didn’t make dropouts, bb’s and headtubes for titanium and steel. It would be so hard to build a metal bike!

Maybe this exists, but if someone made a gravel/road bike chainstay-bb-dropout subassembly, specifically for hobby frame builders, that would really take down some barriers.

Then there is the topic of 3D printing + carbon fiber, which is a great match:
This is a cool example from Brackish Cycles

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Frameworks is doing some really cool stuff winding tubes and doing testing:

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And you could mold/make your own parts like Montenegro

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This is from my perspective, and maybe @Pursuit can chime in here:
I think knowledge is the biggest barrier for carbon bikes. Metal custom frame building has had the benefit of 50 years of trial and error and tribal knowledge. Metal tubes are also much simpler to understand and predict their behaviors.

I can easily create a fully parameterized 3D-printed lugged carbon frame in CAD, but I don’t even know where to start with the tubing diameters, wall thicknesses, epoxy, etc…

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I used to sell tubing when I was at ENVE.

Scott who used to be the head of engineering at ENVE, purchased all their tube tooling for his company Origen MFG

If you are needing to purchase carbon tubes I would highly recommend Scott and his team!

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Wasn’t the guy from Northrop Grumman on here?

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I play hockey with a bunch of Sikorsky guys. I will ask if any are carbon guys. I know one is a blade engineer

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Yeah. The reason why there aren’t a lot of people getting into carbon building compared to steel lugged and fillet brazing is because there isn’t much readily accessible resources out there on how to build with carbon.

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I have built one and am slowly picking away at another frame. My first was wet layup over a foam core. My current attempt is a mix of custom tubes and scavenged lugs.

10 years ago when I built my first frame I did it with a borrowed main triangle jig and scavenged together a rear triangle jig. All in I had about $300 into the frame when it was done.

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I build custom carbon. I think the secrecy is really annoying. But because of the secrecy I have spent years working in places that I didn’t enjoy so I could learn the knowledge I have today.

It’s a catch 22. I want it to be less secretive but I also don’t want to give away my life’s work for free.

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