Henrik Borgwardt and Arne Stahl were working in the aerospace sector, developing methods for manufacturing carbon parts as efficiently as possible, when they decided their technology could apply to the bike world too. The two engineers, who worked for the DLR – Germany’s aerospace center, or the "German NASA" – decided to start making carbon wheels in 2019, and since then have headed COPRO, a small German brand that now makes three versions of the Lilienthal wheels.
The COPRO wheels are unique for a few reasons. First, the Lilienthal AM (all-mountain) and Lilienthal XE (eMTB) rims are filled with foam to help dampen vibrations and further reinforce the rim (though the XC version prioritizes light weight, so it doesn't use the same foam core). Also, the engineers behind COPRO have figured out how to automate a significant portion of the process, which they say helps minimize the potential for human error and keeps costs down.
Internal width: 30mm
External width: 36mm
Spoke count: 28 or 32
Weight: 400g XC, 485g AM, 495g XE
The foam core is similar to what we've seen in some aluminum rims
, but the carbon version is something new.
The impetus for developing COPRO wheels was the development of a roll forming technology while Henrik and Arne were working for the DLR, which is made possible for carbon wheels by the use of NCF, a type of carbon fabric made up of unidirectional, parallel fibers. COPRO says that NCF, compared with woven carbon technologies, allows for lighter weight because the carbon fibers are straight, rather than squiggly, so they can create the same stiffness using less material.
The main benefits of roll forming are adaptability and efficiency, COPRO says. Production is easily scaled up or down, and the process is easily adapted to different rim profiles.
The carbon material comes pre-configured in narrow bands that are roll formed and laid directly into the mold, meaning there is almost no wasted material. The wheels are cured using a process called resin transfer molding (RTM), which involves creating a vacuum inside the heated mold while injecting resin to draw the resin into the carbon layers. Each wheel is cured in the mold before it is removed, then it undergoes quality control testing, has hub-specific spoke holes drilled by an automated machine, and has custom colored decals applied to finish the process.
Although the techniques used are new for the bike industry, the COPRO folks stand behind their products, and they offer a lifetime warranty and crash replacement policy for any of their wheels.
The wheelsets are also fully customizable using an online tool that allows users to customize the colors of the graphics independently for each wheel, as well as pick a driver style, specify hub spacing, and even choose oil slick spokes if desired.
The Lilienthal AM wheelset retails for 1,449 EUR ($1,723 USD) with Hope Pro 4 hubs, and individual rims sell for 449 EUR ($535 USD). More information is available at copro.bike