In the pursuit of radically reduced unsprung weight, aftermarket wheels, whether they be magnesium or carbon, have one significant weakness — torsional loads can fracture their thin spokes and brittle materials. These Rotobox carbon fiber wheels adopt a radical hollow cylinder construction for their spokes, a design that should be capable of withstanding huge torsional forces while achieving the same lightness as thin, solid-spoked rivals.
Rotobox also claims that the increased air volume housed in the hollow spokes will lead to less variance in temperatures and increases tire compliance over rough surfaces. Disadvantages could be increased surface area creating susceptibility to crosswinds, but the company claims the reduced space between spokes is still more than enough to ameliorate this effect. There’s cost too of course, around €3,000 a wheel before you get into hubs and bearings.
Rotobox claims to be lighter than rivals, yet quotes an all-up weight for the wheel and heaviest aluminum hub as over 14lbs. BST claims 4.2-5.2lbs per wheels, so we assume Rotobox is measuring in a different way (ie with hubs and rotors in place) or is quoting an erroneous number.
Around for a year or two in prototype form, Rotobox wheels are now being used by Austrian endurace team YART on their R1 and will be arriving in WERA and AMA this season.