The bike comes with a main frame constructed of scandium, a stronger aluminum. Comparing my previous alumimium frame to the scandium frame, I find the scandium frame to be a lot stiffer and more responsive. To offset scandium's harsher ride, the Moto Rapido has carbon seatstays. My 16-inch frame weighed 3.2 pounds (manufacturer's weight).This is a fantastic bike, super stiff and ultra responsive. The attack is simply fantastic.