Expanded Polystyrene (EPS) molding is the standard for creating carbon frames and forks for the best race bikes in the world. At Knight, we use this same process to create our products.
Most carbon fiber rims look smooth and seamless on the outside, but what’s inside is equally as important. Making a carbon fiber rim involves compressing layers of carbon weave and epoxy resin into a mold to get the desired shape. Traditionally, inflatable bladders are used inside the rim to force the material into the mold, but because the shape of a bladder can’t be finely controlled there can sometimes be wrinkles or inconsistent thickness in the finished rim. These irregularities can lead to delamination or premature stress fractures — every fold, every wrinkle a potential point of failure.
By utilizing an EPS Molding System, we get internal surfaces as smooth and wrinkle-free as the exterior. This increases strength due to the uniformity of the fibers, pushing it into exactly the desired shape with consistent thickness and no wrinkles. The result is a lighter, stiffer and more consistent final product.
We can make EPS forms to the exact shape that we want before laminating carbon fiber around them and placing the whole system in a mold. When heated, the individual beads in the EPS forms swell. Out in the open they’d reach 40 times their original size, but constrained by the mold they exert pressure on the inside of the carbon fiber, pushing it into exactly the desired shape with consistent thickness and no wrinkles.
As the sole rim manufacturer implementing this cutting edge technique within our manufacturing process, combined with our aerospace-grade Toray carbon fiber, used in Boeing’s 777 aircraft and many others; Knight Wheels can offer a lighter weight, stronger, more reliable and precisely constructed rim.