Our superlight top tubes come in Standard (25.4 mm) and Oversize (28.6 mm) diameters, with different butt lengths (long and short). Heat-treated CrMo for ultimate strength and durability. Kaisei makes the best steel tubing in the world, widely respected for its consistent quality and perfect roundness. Long reserved for the track bikes of Japan’s Keirin professionals (who race on steel bikes), Rene Herse offers Kaisei tubing in custom-drawn dimensions for modern allroad and randonneur bikes…