I have a new Giant Escape City that weighs 29.6 pounds, without the panniers. With the panniers and me and 20 lbs of groceries it must weigh at least 240 lbs. If I shaved 5 pounds off the bike's weight (or mine!), that would reduce the total mass by a little over 2%. So I don't worry about it, except when I'm lifting it up to hang in the garage.