Argonaut’s GR3 merges custom carbon with a modern approach to gravel

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Based in Bend, Oregon, Argonaut is a boutique custom carbon frame manufacturer with a rather atypical approach to making bikes. The company keeps a slim range but today, a second option was added to its website – the new GR3. And as is often the case with the boutique brands of the custom bike scene, this fully integrated and aero-looking performance gravel bike offers a few ideas that I suspect we’ll see become more widespread in years to come. 

Admittedly, the most tech-keen readers will recognise this new gravel-focussed bike as one that has been spotted out in the wild for several months, most notably under sponsored athlete Sarah Max. Now it’s official, and with that comes the specific details. 

The bike and the geo 

The new GR3 is a bike that aims to provide performance-based versatility by combining custom carbon manufacturing (I’ll come back to this), clearance for up to 700 x 50 mm tyres, and a progressive gravel-focussed approach to geometry. 

Argonaut achieves that generous tyre clearance while keeping its chainstays at an impressively short 415 mm. Off the top of my head, this is surely one of the shortest lengths for a given tyre clearance, although it does come at the expense of being able to run a front derailleur.

The 68.5º head angle is another interesting design decision, and that slack-and-presumably-slow figure is then sped up with a long, 57 mm offset fork. The result is a 79 mm trail figure (700 x 40 mm tyre), and one that should slot in nicely between the BMC URS and Evil Chamois Hagar

Progressive-geometry gravel bikes often combine slacker head angles with longer reaches, but that combination isn’t seen here. Rather it appears that Argonaut is achieving a lengthened front centre by moving the front wheel out, all while keeping its fit dimensions in more familiar territory. (Note: wheelbase figures are missing).

Those geometry figures and the stack and reach are pre-configured and offered in seven sizes. Argonaut does have plans to offer wholly custom-fit versions of this model, but such things are likely a year away. 

Cables and hoses are nowhere to be seen on the GR3, and are hidden through the company’s matching stem. Argonaut makes no claims of aerodynamic gain and rather points to the hidden cabling being beneficial for those wanting to run a handlebar bag, and just making it an easier bike to clean. I don’t disagree with such claims, but keep in mind that future headset services will come at a premium due to the design.

Beyond that, things are noticeably simple, including the use of a regular handlebar (albeit one that allows internal cabling), a round seatpost held with an external clamp, and an external-type T47 threaded bottom bracket shell.

There may be integration up front, but things are far simpler out back.
A T47 threaded bottom bracket.

Custom frame manufacturers rarely tout frame weights, partly because they vary based on the intended use, but also because they’re rarely an attractive figure. However, Argonaut’s manufacturing process (detailed below) produces some impressive figures, with G3R frames claimed to start from just 850 grams, with the matching fork at 350 g. The stem weight is 135 g in a 120 mm length. 

Pricing for the Argonaut GR3 begins at $6,500 for the frameset. Current build times sit at four months from the order date. 

Custom monocoque carbon

“Custom monocoque carbon”. These are three words that are rarely combined when talking about bicycles. And yet, it’s how Argonaut approaches the manufacturing of its bikes. 

Monocoque design is the only common manufacturing method in carbon fibre bicycle frames. The specific process varies, but the fundamentals of making a monocoque frame involve layering sheets of pre-preg carbon fibre around a removable core material (aka a bladder or mandrel) and then carefully putting that into a fixed mould. The inside bladder is then pressurised and the mould heated, resulting in a carbon frame (or component) that matches the shape of the outside mould. If you ride a carbon bicycle and it’s a brand raced in the WorldTour, then chances are it’s of monocoque construction (unless you ride a Colnago C series).

Monocoque carbon is the cycling world’s go-to method for creating strong structures with best-in-class weight . The downside is that expensive tooling needs to be made for each specific frame size, which doesn’t easily lend itself to customisation for each bike. As a result, most custom carbon bikes are made using other manufacturing methods – such as tube-to-tube – which unavoidably means more redundant material.

Argonaut’s bikes are made in Bend, Oregon using well-proven monocoque manufacturing techniques similar to the mass-produced bikes out of Asia, albeit with a few twists. The American company has its own patented silicon molding process that produces incredibly consistent and clean results, which it dubs “High-Pressure Silicon Molding Process”. 

There aren’t many visual cues to tell you this is a custom bicycle.

“We CNC our tooling out of aluminum and we then create mandrels out of silicon,” explained Argonaut’s Erik Bergstrom. “We apply carbon to the silicon mandrel. Every layup pattern applied to the mandrel is unique to the rider. Once the carbon is applied, it is placed into the aluminum tool, cranked down and placed in the oven to cure the epoxy in the pre-preg carbon. The silicon expands during this process, eliminating any deformities or imperfections. The result is carbon pieces that are as perfect on the inside as the outside.” 

While the monocoque moulds are best suited to fixed-geometry bikes (the company does offer custom at a premium), Argonaut adds the custom touch with a specific carbon layup for each frame order. Are you a light rider that often finds mass-produced bikes too stiff for your liking? Argonaut’s process aims to answer that. Just want a bike stiffer than a 2×4 that feels fast but is in fact probably slower? Yeah, the custom process allows that, too.  

“We try to get as clear a picture as possible about who a person is and how they need their bike to feel and perform,” Bergstrom said. “Some people want stiffer machines to beat their buddies to the next sprint point, others are looking for something to go all day on roads that are from pristine. We work to deliver a bike that meets exactly what they want. And, of course, rider weight and physiology play a role in this.” 

Argonaut’s last bike release, the RM3 road bike, came with news of forks being built in-house. That, unfortunately, didn’t last. Much like other high-end fork options, the company has since gone back to outsourcing the manufacturing of the forks unique to the brand. “Our ethos is this: if we can make something better than anyone else here we do it,” explained Bergstrom. “If we find that someone else can actually do it better, then we go with the best option. We made forks in the past, but the price we would have to charge for an in-house made fork was not viable. So, we have a partner that makes them every bit as good as we would, but the price makes more sense.” 

There’s little doubt Argonaut produces some highly desirable bikes with prices to match. However, arguably more fascinating is just how much attention these small boutique brands get from the biggest names, and how the ideas you see here so often filter into more mainstream product offerings.

OK, that’s enough of that. Time for images.

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