Tech features Behind the Curtain: Argonaut Cycles factory tour
Ever wonder how the boutique carbon brand manufactures its frames? Well, wonder no more.
Behind the Curtain (we’ll see if the name sticks), a new and recurring series at Escape Collective where we take you behind the scenes at various factories worldwide to show you exactly how the sausage is made. Aside from companies maybe covering travel costs, rest assured these are not sponsored articles in any way. We still ask the questions we want to ask, we still show what we want to show, and we are by no means trying to sell you anything (although we also reserve the right to say when we think something is cool, too). Want to see more of these? Make sure you sign up to become a member of Escape Collective. And if you’re already a member and have suggestions for who we should visit, go ahead and leave them in the comment section below. Argonaut Cycles has been around since 2007, but it wasn’t until founder and builder Ben Farver switched from steel to carbon fiber in 2012 that he started to stand out from the crowd. While many brands at the time were deeply immersed in the weight weenie wars prevalent at the time, Farver was instead more interested in how to replicate the ride quality of steel that he’d always enjoyed. That the composite frames he was making happened to be light while also closely mimicking the classic aesthetic of metal was a nice bonus.
Farver doesn’t shy away from the fact that he’s made some mistakes along the way (haven’t we all?), but he’s also learned a lot in the process, culminating in the development of Argonaut’s latest RM3 road and GR3 gravel bikes – the only two bikes in the entire company catalog. Both incorporate a novel (and supposedly patented) construction method that Farver claims is not only superior to more conventional processes, but one that’s also adaptable for an unusually broad range of custom geometries and stiffness/flex characteristics while still offering the ride quality benefits he’s been chasing for the last decade.
But does all of this make for a better bike, or one that even fully justifies the sky-high asking prices? It’s not for me to say what’s “better” for a particular rider, and while Farver fully answered all of the questions I presented to him, I wasn’t about to dig into the company’s balance sheet. That said, the unusually laborious nature of Argonaut’s construction methods is hard to dispute, and if nothing else, it was quite the sight to behold.
I hope you enjoy this virtual tour, and fingers crossed, we’ll have another Behind the Curtain installment for you sooner than later.
Argonaut hasn’t been a brand to go after the numbers, instead preferring to chase the elusive unicorn of “ride quality” since shifting from steel to carbon frames more than 10 years ago. But while mainstream brands will regularly overhaul their lineups every three years or so, Argonaut’s story had mostly been one of refinement up until the RM3 model release three years ago. Argonaut founder Ben Farver started out building steel frames because that’s what he personally liked to ride; they just felt better to him. Upon switching to carbon, he sought to replicate that springy feel, but with an even more refined ride quality and – of course – much lower weight. Argonaut occupies two separate workspaces in Bend, Oregon. The facility shown here houses R&D and frame component manufacturing. The frames are then assembled, finished, and painted just a few minutes down the road. “Compaction” is a big buzzword when it comes to carbon fiber manufacturing, and it essentially refers to how much the plies can be squeezed during the curing process to drive out excess resin and minimize voids. Whereas most carbon fiber frames still use some form of compressed air inside the frame to push the plies out against a heated metal clamshell mold, Argonaut relies on the concept of thermal expansion.
Carbon plies are laid around a silicone rubber pre-form (left), and that assembly is then loaded into an aluminum two-piece mold (right). That silicone pre-form expands inside the heated oven more than the aluminum mold does, which Argonaut says results in about 600 psi of pressure on the carbon fiber plies – supposedly almost three times more than what you’d get using compressed air.
Argonaut produces everything shown here in-house. The silicone pre-forms are poured using plastic clamshell molds (center) that are made on one of two in-house 3D printers, for example, and the aluminum molds are machined on an in-house CNC mill.
This vertical manufacturing process is what allows the company to offer fully custom frame geometry in reasonable time frames. Those silicone rubber pre-forms may be how Argonaut gets such high compaction pressures inside the mold, but they also require a lot of prep work early in the manufacturing process. Any excess flash has to be cut off by hand, for example. Sixty pieces of carbon fiber pre-preg go into a single bottom bracket assembly. And how about an entire frame? Make that 373. Each ply of carbon fiber has to be placed in a very specific location and orientation on the pre-form if the finished part is to have the intended structural properties. But before a single piece of carbon is placed, the silicone rubber pre-form is strategically covered in “release tape” that makes it a little easier to remove it after curing. Even with that tape in place, though, the silicone pre-forms in more complicated parts like this bottom bracket assembly can only be extracted in chunks after molding. Those pieces can’t be re-melted, but they can at least be used as filler bits in other silicone rubber pre-forms so less ends up in the trash. The majority of the cost in manufacturing carbon fiber bicycle frames isn’t the material itself; it’s the labor. Even with some brands recently enlisting the help of robots, even at large factories for major brands, it’s still mostly human hands that are putting all of this together – and for the folks at Argonaut, that process is very, very deliberate. Mass-produced carbon fiber frames are typically cured inside big steel clamshell molds with hookups for compressed air to create interior pressure. The whole thing resembles a huge waffle iron. Since Argonaut uses thermal expansion of the silicone rubber pre-form to provide the compressive force on the carbon plies, there’s no need for air hook-ups here. Also, steel molds are usually preferred for mass manufacturing since they last longer, but since Argonaut is only producing a couple hundred frames annually (and in a broad range of sizes and geometries, which further spreads out the wear), the company can get away with using aluminum molds instead. Each Argonaut frame is composed of 10-11 separate sections of carbon fiber, each of which has to be built and molded individually. Just as nearly every different size and geometry of frame component requires its own outer mold, each also requires its own silicone rubber internal pre-form, too. Farver says there are currently 192 internal molds – and counting. The internal finishes on the parts using the silicone rubber pre-forms are quite smooth and free of any extraneous leftover material that might hinder internal hose routing. Keep in mind, too, that this part is straight out of the mold with no additional finish work. Farver did the math early on in the development of the current RM3 road bike model and concluded it would be more economical in long run to buy a Haas CNC machine and hire an operator to run it than to farm out the manufacturing of all those aluminum molds elsewhere – never mind the added benefit of quicker turnaround times and more flexible manufacturing. This lathe isn’t nearly as massive as what you’d often find in a framebuilding shop that specializes in metal construction, but this particular one has still clearly seen some things. Aluminum blocks are kept on hand for when a fresh mold needs to be cut. These 3D printers were resting peacefully during my visit to Argonaut, but they definitely get a lot of use overall. The complete collection of external molds are stored here – 205 in total (or 410 halves). Whatever is needed for a particular part is loaded on to a rolling cart and transferred over to the adjacent room. Stems are molded in-house, too. Main tubes are built a little differently from more complex things like bottom brackets and head tubes. Plies are roll-wrapped around a solid Delrin mandrel, and then the assembly is captured inside a four-piece aluminum mold. As with the silicone rubber pre-forms, the Delrin mandrel produces outward pressure on the main tube walls as it expands inside the heated mold. Once everything is cooled, the mandrel slides right out of the finished tube. Main tube mandrels are marked according to the target tube stiffness since they’re subtly different in size.
“We control flex of the frame using the amount of fiber, and fiber orientation,” Farver explained. “Different size mandrels account for the different amount and thickness of fiber in the frame part.” Farver says that carbon fiber pre-preg materials can vary a bit in terms of their material properties, even when purchased from the same manufacturer. As such, he prefers to buy an entire run at a time so he knows the entire batch is identical. All of the raw materials are stored in a big industrial freezer. If you’ve ever been to a carbon frame manufacturer (or even just seen pictures from inside of one), then this machine will look familiar. Rolls of raw fiber are loaded up at left, while a computerized blade cuts out the individual pieces. Each assembly’s worth of carbon pieces is gathered up and stored in a plastic sleeve. Cylindrical tubes are far easier to build than the more complicated frame pieces, although even these are surprisingly tedious to do properly (as I found out firsthand, seeing as how I ended up building most of the tube shown here). Unidirectional carbon fiber pre-preg is funny stuff to handle: very stretchy in one direction, but not in another. It’s critical to keep track of which piece is which, and a lot of care has to be exercised when handling each piece. Individual layers are first tacked on to the mandrel along one edge of the material, being careful that the edge is perfectly lined up along the long axis of the mandrel. The rest of the carbon ply is wrapped around the mandrel and rolled with hand pressure along a flat granite table. Rolling the mandrel along the flat granite table helps ensure the material is wrapped tightly around, and also minimizes any trapped air bubbles. The inside ends of each tube are first wrapped with a layer of woven fabric, as that creates a better bond with the adjoining lugs later in the process. The yellow material in the middle is aramid (better known as Kevlar), which provides some vibration damping and impact resistance. The first layer of UD fabric is wrapped around the mandrel. Since many Argonaut frames are sold with a raw finish, it’s important that all of the seams are straight and in the correct orientation since there’s a good chance blemishes won’t be hidden under paint. After all of the plies are installed, the assembly is placed into the mold. Rubber seals are used partially to keep any excess resin that’s pushed out of the pre-preg from flowing all over the place. But the more important role is sealing the chamber so the internal pressure can build to the target amount. The massiveness of these mold halves may seem excessive, but wait until you see the hardware used to hold everything together. Argonaut says the Delrin mandrels exert so much outward force that the company had to switch to bigger thru-bolts and nuts to hold everything together inside the oven. Earlier designs used bolts that fastened directly into the mold body, and those threads were occasionally ripping out under the pressure. Excess carbon fiber and seal material are sliced off before the end caps are installed. Each end cap is fitted with its own o-rings and held in place with four big steel bolts. Each frame component is essentially cured inside an industrial pressure cooker. Time to bake! Each frame component mold is relatively small so several of them can fit into the oven at once when things are busy. It’s critical to keep track of how long everything has been in there. Straight out of the mold. Not bad at all. Argonaut makes a big deal about the ride quality of its bikes, but have you ever wondered how it actually goes about producing that? Farver says there’s a lot of trial and error involved – and lots of ride testing – but test rigs like this also provide a lot of empirical information on things like flex patterns so something that feels good out on the road can hopefully be more accurately replicated, and something that doesn’t feel good can get tweaked. This particular test rig can also be set up in a few different configurations for various ISO safety tests. Not seen in this image are the other two test rigs in the other two corners of the room, all of which are reassuring to see in a brand with a production volume as small as Argonaut’s. Completed frame “kits” are gathered in plastic bins with the associated paperwork and sent off to the other Argonaut facility for assembly. Argonaut uses so-called scarf joints for the bonds – basically a tapered interface that supposedly yields stronger bonds than a straight shear or stepped geometry. While one half of the scarf interface is molded directly into some parts, the ends of some tubes (main tubes, in particular) have to have that geometry ground into the ends. A single titanium piece incorporates the thru-axle threads and derailleur hanger mount. That and the flat-mount brake caliper inserts are all bonded in separately after the dropouts come out of the mold. Dropouts use a slightly different bond joint geometry with a more subtle taper.
“The smaller diameter of the dropout doesn’t require as gentle of a taper to spread the load across the joint,” Farver explained. This jig is used to face the bottom bracket shells after the titanium threaded rings are bonded in place. Each subassembly has its own bonding jig to reduce the potential for mistakes along the way. So smooth. Getting there … More titanium can be found in the headset bearing seats. Final assembly is done on these Cobra frame building jigs. The entire thing can be wheeled straight into the curing oven, which is big enough to bake two frames at once. Frame alignment is checked here after all the bonds have cured. Argonaut says the total tolerance is +/- 1 mm at any point on the frame, but “things are generally coming out within 0.5 mm, often even under 0.2 mm across the board.” Any aesthetic imperfections in the bond joints are addressed with a bit of filler from aerospace supplier Airtech. “Invariably there are little bubbles in the adhesive that migrate to the surface when curing,” Farver explained. “Airtech is a durable, paintable, and stable filler that we use to fill these pinholes. We don’t get pinholes in any carbon surfaces; just the bond gap at the bonded joints.” Bond joints are sanded by hand. So many sanding steps. The finished joints are definitely very impressive to behold. Unlike most companies using bonded carbon fiber frame joints, Argonaut doesn’t rely on any overwrap layers to clean things up. Frames in process. Anyone see their name in there? After some experimentation with third-party painters, Argonaut now handles all of its finishes in-house. Stems can be painted to match, too. Not far off now. No greasy fingers, please. An essential piece of equipment for any successful operation. Like most bike companies, Argonaut is a dog-friendly business – always a good indicator of the quality of the people inside. What did you think of this story?
😐Meh 😊️Solid 🤩Excellent