Honestly I don't know what our XL Paketa Tandem frame weighs, but we won Masters Nationals this year on it and it is very stiff. We had over 5000 feet of climbing around and up to Mt. Bachelor, OG. It is amazingly light, climbs and handles like a dream. We got the 1.5 inch head tube for the tapered fork, 1.25 X 1.5. This thing is awesome! Ask the guys we beat that were on the custom Calfee.