To achieve this effect, we insert the tubing into special dies that we've made. Then we use a hydraulic press to re-shape the tubing in the desired zones.
The look of the bike is unique, and the ride is phenomenal. We ovalize the top, stiffener, keel and down tube in strategic areas. The end result are tubes that flex up and down more that round tubes, making the ride more comfortable. At the same time, the bike becomes more laterally stiff, and accelerate faster. If you're a couple that likes to stand and climb hills on your tandem, you'll really appreciate that. I speak from experience.
Note: If you are choosing an travel version (S&S couplers), then ovalizing is not available for the whole frame.