When Alchemy introduced the Arktos 29 at the Sea Otter Classic in 2018, it wasn’t much of a surprise. Alchemy had debuted a 27.5-inch wheel version of the Arktos three years earlier, and it seemed natural for a larger-wheel-size version of the bike to exist. But the Arktos 29 was long in the making, overall taking two years from inception to wheels hitting the dirt. For Alchemy, this isn’t the exception. Every Alchemy bike goes through an extensive development process like the Arktos 29.
// US Design and Development
The start of any new suspension mountain bike frame begins with the kinematics, in this case by David Earle, the designer of the Sine Suspension System and a legend in the bike industry. David starts by determining the dynamics of the suspension system, ensuring the bike will climb, descend, and generally handle the way Sine was designed. This process, because of the experience gained on the Arktos 27.5 and Sine, is typically pretty short, taking around a month.
Once David is finished with the kinematics and overall suspension design, he passes it off to Alchemy’s Matt Maczuzak, one of the principals of the company and the person responsible for Alchemy entering into carbon with road bikes 8 years ago.
Matt works first on the overall aesthetics of the frame, ensuring that visually the frame will match the overall look of Alchemy’s mountain bike lineup. After that, the real work begins. Matt’s long experience with carbon comes in to play as he looks to determine the carbon layup that will maximize strength and stiffness while minimizing any added weight.
Alchemy is unique in that we are one of the few US companies with the capability to design and prototype carbon frames at our facility in Colorado. This enables Alchemy to completely understand the dynamics of a new bike before it goes into full production. Most manufacturers are forced to prototype bikes with aluminum, which only allows them to get a “feel” of a new bike. Aluminum prototypes are typically 30 to 40% heavier than the carbon models, so the ride quality is significantly affected by the weight of the proto itself. Alchemy can also prototype exact replicas to production bikes.
// The Carbon Layup
The carbon used in bicycle frames is called prepreg. Prepreg is the common term for sheets of carbon that have been impregnated with resin. The resin is typically an epoxy with a curing agent so the carbon can be hand placed directly into a mold for curing. The main advantage of prepreg carbon sheets are their ability to be highly engineered, easily handled and the carbon to resin ratio is very consistent (eliminating imperfections at the prebuild level of course results in a more consistent frame). Alchemy buys carbon prepreg sheets directly from Japan and has a CNC cutting machine to create the shapes necessary for use on a frame.
When Matt is looking to optimize the frame layup, what he in reality is doing is determining the layering and orientation of the prepreg fiber sheets. Engineers like Matt can provide almost any desired strength and torsional stiffness by varying the quantity and orientation of the fiber sheets as they are applied in the mold. Carbon is unique in that it is relatively easy to add strength only where needed, while significantly reduce weight elsewhere by proper application of the carbon prepreg. For the Arktos 29, extra material was placed in key areas requiring high strength, such as the head tube and bottom bracket, and both the orientation and layers of prepreg used are proprietary to each Alchemy 29.
// The Molds
Alchemy is also unique in that we CNC machine all of our molds in house at our Colorado headquarters. Again, it’s Matt’s expertise that comes into play.
“I’ve been machining the molds for the road bikes for years,” says Maczuzak. “But my first experience with a monocoque design was with the Arktos 27.5 frame. We use a tube to tube construction on the road bikes, so the molds are smaller in comparison because the individual pieces themselves are smaller.”
The Arktos 29 is a monocoque design as well, meaning that the entire front triangle comes out of the mold in one piece. The rear triangle comes out of the mold as two individual pieces that are then joined together in a secondary mold process.
Matt cut the prototype Arktos 29 molds from aerospace grade 6000-series aluminum, starting with the medium size frame for prototyping and ride testing. It took about 30 days from mold-design completion to the point when the first front and rear triangle were pulled from molds. The majority of this time is spent determining the lay up schedule.
// Next Steps
Alchemy has been painting frames at its headquarters in Denver since the start, and like most prototype carbon frames, the first Arktos 29 was painted white. Painting the surface white allows us to easily see any potential cracks in the carbon during our lab and ride testing.
The ride testing period for the Arkos 29 was actually pretty short, mainly because the bike reacted as expected during the lab and ride tests. Alchemy EWS racer Cody Kelley was one of the first people to put any significant time on the frame, and quickly came back impressed.
“It both pedaled and descended super well,” says Kelley. “And the geometry was spot on. I felt super comfortable on the prototype right from the start.”
// To Production
As anyone who has visited Alchemy in Denver knows, the factory is set up to hand build each bike one at a time. While this process is excellent for tube-to-tube construction, it is far from efficient when making a monocoque frame like the Arktos 29. Building a monocoque frame is more suitably done in batches, as the labor-intensive process requires many fabricators working in unison on each frame. This ensures repeatability and guarantees every Arktos is of the highest quality.
We chose to partner with one of the most distinguished manufacturers in the world, a company that has been working with carbon for over 30 years and is known to produce some of the lightest, strongest carbon frames on the market. But, our development process didn’t just stop with the pass off of the drawings and the layup schedule. We work directly with the factory to ensure that our strict quality standards, as established in Denver, are followed to a “t”. We also continue to quality check throughout the process to see that the frames follow the same procedure with each production run.