Challenge criterium open road tyreforever the choice of professional riders numerous victories and podiums have proven criterium the top pro racing tyre open tubular differ from traditional clinchers for the construction the tyre is produced just like a tubular and uses the same materials and production process instead of being sewed with an inner tube inside at the end of the process beads are made by folding the casing around aramid fibers threads for this reason an open tubular gives ver