The second major difference between the C59 and the C60 is the new oversized downtube. The new shape of the bottom bracket allows for the use of a much large tube diameter, thus greatly increasing lateral stiffness. With a square section of approximately 66x52mm (the C59 was only about 44mm) this tube represents the largest tube ever produced by Colnago. This increase leads directly to more efficiency, while at the same time reducing weight without sacrificing comfort.
Like the top tube, the star-shaped profile of the downtube runs the full length of the tube as it enters the lug, better distributing negative forces fromthe road surface. This tube profile improves lateral stiffness and efficiency, reduces weight and increases comfort.