Originally Posted by
tarwheel
Weight matters as much more more than rolling resistance. I have been keeping records of all of my rides for many years and tens of thousands of miles, including average speeds, distances, times, bikes that I rode, etc. My data consistently show that my lighter bikes with narrower, lighter tires are faster than my heavier bikes with fatter tires. The average speed on my lightest bike is 2.5 mph faster than my heaviest bike. The correlation is almost linear, with speeds steadily increasing from my heaviest bike (touring) to my lighter cyclocross, sport touring and racing bikes.
Your data, as described by you, is useless for determining the effect of weight, because you're comparing different bikes. You've introduced too many confounding variables.
Weight doesn't matter for the typical commuter. Our weight varies by so much daily that the difference in tire weight is smaller than daily differences in load weight.
For others, weight doesn't matter as much as you seem to think. My cruising speeds on tour, with a bike+gear weight of 139 pounds, were very close to my cruising speeds on the same bike+commuting gear, weighing about 50-60 pounds.