Originally Posted by
SBRDude
In one extreme, if the rider is already very heavy and has a heavy load, then the weight savings of 5-7 pounds isn't going to make a dramatic difference. But, if the rider is of a normal size and is going to be riding with an empty or light load, then the weight savings will be much more noticeable. With all that in mind, ANY weight savings will be translated into a greater bang for the buck for a constant amount of power input by the rider, irrespective of their conditioning. It's just a matter of whether or not that bang is worth the extra bucks to the particular rider.
In climbing, you might notice 5 pounds. In the flats, you won't. Air resistance is just so much larger than drag from weight at speeds greater than about 10 mph that weight is not much of a factor in the power required to maintain a given speed. That's why time trialists will take a weight penalty for more aerodynamic wheels.