Frame Size 20.5/18 (BB-Top Tube). Oversize 4130 chrome-moly tube set. Caliper brakes front and rear. Shimano 105 components. See photo from catalog for specifications. Saddles and pedals not original. From catalog: "The elegant Duet strikes an ideal balance between stiffness, comfort, responsiveness, and weight. We believe it to be the best riding road tandem in the world."