picked up sons cannondale caad9 r5 the other day. man is that light. i suppose the light weight is a function of many light parts? perhaps not so much the frame. my rigid mtn bike has an alum frame. my fork is steel. caad has carbon. caad seat is the size of a nail clipper. my seat is off a tractor. his wheels/tires are rubber bands. mine are off a 4wheeler. its a 08 model but has rh-550 wheels? that was not stock was it?