When Atomik Carbon set out to produce high-performance carbon fiber fat and plus rims, we knew we had to think outside the box. We wanted to maintain the stiffness and ride quality carbon is known for, without the tall rim profile often needed to maintain those qualities. And we wanted a rim capable of shrugging off impacts and trail damage.
GOING LOW + VERTICAL COMPLIANCE VS. STIFFNESS
We knew we wanted a low profile rim. The lower the profile, the fewer impacts from trail debris and the less surface area for muck and snow to cling to. But with traditional double wall rims, unwanted flex is an unavoidable byproduct of a lower profile. Other manufacturers claim to engineer in “vertical compliance” on their low profile rims, but we know better. Carbon’s ride quality comes from its natural damping properties, not from vertical flex.
At Atomik Carbon, we manage vertical compliance by incorporating a “range” of allowable flex to very specific tolerances. We engineer unwanted flex out of our designs because there are other factors that allow compliance and can be used to fine tune the end user ride quality of a wheel, including spoke choice, spoke tension and lacing pattern. To track straight and true, especially with high volume tires, lateral and vertical stiffness is a must.
In testing traditional double wall designs, around 25 millimeters we began to see unwanted vertical flex, or “compliance.” By wrapping a single layer composite wall around an aerospace grade foam core through a patented process, we were able to achieve an astonishingly low 15-millimeter profile on our plus rims, and an equally impressive 16.2-millimeter profile on our fat rims. That’s 66 percent lower than the competition. And we did it without unwanted flex—in fact, they’re every bit as stiff as traditional 30-millimeter double wall designs. We also found that the foam core improved carbon’s already superior damping qualities.
The result? A low profile rim that maintains the necessary stiffness—both laterally and vertically—for precise and consistent tracking when riding hard in rough terrain with unparalleled ride quality and damping. In essence, the best of both worlds, and the first of its kind.
OPTIMAL WIDTH + IMPACT RESISTANT
The low profile means there’s less surface to be impacted by trail debris. In fact, more than 75 percent of impacts on a standard rim occurred above the 15-millimeter mark. This means your rims stay looking newer, longer. But while we love looking good, there’s more to durability than appearance.
“Wider is better” seems to be the industry trend when it comes to mountain bike wheels. And it’s true, to an extent. When testing widths for our plus and fat rims, we went wide. So wide, in fact (up to 50 millimeters on our plus rims), that we found a point of diminishing return on optimal tire footprint and traction. We also found that beyond a certain width, the rim was less protected by the tire and more prone to impacts.
The widths we arrived at for our plus and fat rims—43 and 85 millimeters respectively—were the optimal balance of a wide, confident tire footprint and minimal impacts at the sidewall.
But when things do get ugly, the HDP Foamcore, coupled with our unique profile and 3.5-millimeter sidewalls also dissipates the force of impacts throughout rim, rather than concentrating it at the point of contact. During destructive impact testing, our HDP Foamcore rims failed at a much higher force than what most users would ever encounter on the trail. And when they did fail, the break was minimalized and spread evenly across the surface of the rim, which held air and remained rideable, rather than a localized catastrophic failure at the point of impact. And as unlikely as it is, if you find that limit, that can be the difference between not only avoiding a dangerous crash, but between riding or walking out.
A DIFFERENT APPROACH
When we created our HDP Foamcore plus and fat rims, we looked at other sports and applications of carbon fiber. We consulted with aeronautical engineers, F1 engineers and sporting goods designers that use carbon fiber in high-stress, high-impact environments like hockey and lacrosse.
The result is an industry first. There is nothing else like Atomik Carbon’s Solowall HDP Foamcore technology on the market.
Designed for a variety of conditions from shredding snow-covered singletrack, to epic backcountry bikepacking adventures, to surfing pumice and everything in between, Atomik’s new fat and plus-sized offerings continue to evolve carbon engineering with a ride quality that simply must be experienced to be believed.
But don’t take our word for it.
EXPLORE: CHUBBY 43 – 27.5+ rims and wheels featuring HDP Foamcore Technology
EXPLORE: PHATTY 85 – Fat rims and wheels featuring HDP Foamcore Technology
SHOP: Find your local Atomik dealer or visit our webstore.
