I agree that often folks have unrealistic expectations when they move from a 20 lb bike to an 18 lb bike, or 18 to 16. BUT, moving from a 25 plus pound bike (typical hybrid) to 18-20 will make a difference. So will moving from a hybrid to a road bike, where in addition to weight savings, she may get a more effecient position (with proper fitting), a more aerodynamic postion which can cheat the wind, more hand positions, etc. I do think that someone who is averaging 14-15 mph on a hybrid is probably topped out, and will benefit from a move to a road bike.