Here at Guerrilla Gravity, we dream big and always want to take advantage of the latest developments in technology, whether on the manufacturing side or on the component side. Most of you will see the results of this by having cutting-edge suspension, drivetrain, and wheel tech on your bike due to our short supply chain. Behind the scenes, our manufacturing line has always taken advantage of the latest tooling available to use in our machinery and the greatest design software out there. Much like the guerrillas in our namesake, we have to play smart and change the rules to our advantage in order to beat the big guys. We believe we have accomplished both goals with Revved Carbon Technology.
Building out a brand new carbon fiber production line has been a longtime dream due to the performance potential of carbon. In an industry that celebrates small incremental changes, we had far more disruptive plans and kept hunting for new materials and manufacturing techniques. We drew a line in the sand, knowing that we wouldn’t be fulfilling our mission of making mountain biking more awesome if we developed and released another $4K+ carbon MTB frame.
We needed to pioneer a new way to make bikes in Colorado that could compete with the economies of scale offered by the larger overseas factories. We chased down short-strand fibers and recycled fibers for the cost savings they presented but the stiffness wasn’t acceptable. At this point we switched to full length unidirectional fibers and began researching the latest automated fiber placement technologies made possible with Revved Carbon Technology.
The first carbon fiber bikes were made 30 years ago and we flipped over a lot of rocks in the quest to find some black gold out here in the Rockies. Eventually we were turned onto the newest carbon fiber materials being made in the USA, materials that blew impact strength out of the water with competitive weight and strength to traditional carbon fiber. These new materials require significantly more tooling to manufacturer, something that isn’t a problem if you have the machinery and know-how to design and build the tooling yourself. However, if you’re not actually making your own bikes, Revved is completely incompatible with the machines that built those first carbon bikes in the early 90s, the same machines still building mountain bikes the same way 30 years later.
With the Revved material hunt behind us, the next step was figuring out how to create hollow-form structures out of it. You see, up to this point, Revved and its sister materials had only been used in panel-based structures in automotive and aerospace applications. After trying and iterating with several potential manufacturing methods, the unique Revved manufacturing methods were identified and our patent was filed. The two unique manufacturing secrets that the engineers let us talk about are Revved’s use of automated fiber placement during the layup process and a blazing-fast fusing technique never before used in the bicycle world.
The next step was productionizing Revved. It was at this time that we brought Ben onboard to oversee the development of the manufacturing process and manage the layup for each frame. Ben designed some control samples and began lab testing hollow tubes in different layups and wall thicknesses to simulate the forces a bike frame undergoes during riding. Countless variations of unidirectional fibers and woven fibers were tested to see what would work best in each part of the bike frame and gather all the data needed for finite element analysis (FEA) simulations. Ben used Altair Engineering’s Hypermesh and Optistruct, two extremely advanced FEA software programs, to model the wide range of load cases a mountain bike frame experiences throughout the suspension travel and regularly expected impacts and stresses. Topology optimization was used to have the computer crunch away for hours with different carbon ply orientations to maximize strength of the layup. You know how woodworkers say to measure twice and cut once? FEA software is just like that, except it’s like measuring hundreds of thousands of times as you simulate fatigue loads to see where high stresses develop and modifying your designs accordingly before ever cutting a mold or laying down fibers.
If there is one common similarity between Revved and the traditional carbon manufacturing method, it’s that they both need bladders. But that’s kind of like saying your childhood pedal car and your F150 both need wheels. The new Revved material sees temperatures and pressures that are significantly more demanding than that of the traditional materials, meaning that none of the known bladder materials would work. After testing numerous different bladder materials and construction techniques (sound familiar?) we were finally able to dial in our bladder production process. While we could have easily written another entire article on the trials and tribulations of designing our own bladder systems, it’s far less glamorous than talking about carbon fiber bikes, so we’ll just leave it at: “it was f*ing hard.”
After the proof-of-concept testing was completed, Matt finalized the kinematic and geometry tweaks, as well as the Modular Frame Platform and GeoAdjust for the 2019 bikes. With the geometry locked down, Ben completed the Revved layup schedule for the automated fiber placement (AFP) machine. At this point, GG was in the business of making carbon fiber bikes so we picked up a second CNC machining center and did what every good manufacturer does, started making our own tooling. Armed with two CNC machines, two engineers, and a few rockstar machine operators, we produced our Revved assembly line from scratch. We’ve built our company on a punk-rock DIY ethos, why stop now at such a pivotal moment in our history?
Stay tuned for the next Dispatch where we’ll discuss the development steps taken after the first Revved frames were produced!