Originally Posted by wphamilton

If our hypothetical roadie is putting out 160 watts and weighs 150 pounds he'd be going 19.4 mph on the flat road.

Give him another 50 pounds and he's going 18.6 miles per hour.

estimations from an online power calculator (21 pound road bike, on the drops, everything else default values)

.8 miles per hour difference is not nothing!