Rene Herse x Kaisei Seat Tubes


Superlight seat tubes with different butt lengths for large and small frames. 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.

  • Custom-drawn to our specifications
  • Heat-treated CrMo
  • 'Short' size: 610 mm, with shorter thin bellies and longer butted ends, for small frames and where extra strength for front derailleur braze-ons is desired
  • 'Long' size: 650 mm, with longer thin bellies and shorter butted ends, for large superlight frames
  • Made in Japan