Zipp Vuka Alumina Extensions – 22.2mm 360mm Bead Blast Black. To help every rider find their fit Zipp has created different shapes for the Vuka Aero and Vuka Clip.Sold as pairs. Vuka Alumina Race, featuring a 52mm of rise, was designed using data compiled from thousands of fit sessions with recreational and professional cyclists and triathletes by the worlds best fitters. The Vuka Race bend places the wrists at a more natural bend to help riders remain in their tuck to optimize aerodynamics.