Originally Posted by JavaMan
When you ride 5 miles up a hill, 5 miles is not the horizontal distance!
You are right, but it makes a difference in our case of 0.2 degrees and 0.4% gradient (and will always make a negligable difference in biking terms since the elevation gain <<< traveled distance unless you're doing sick, sick climbs). For doing quick and easy gradient calcs on the fly, rise over (fake) run is good enough for government work!