Okay, I now have some data on my hills, but I need to be able to translate it into a grade percentage.
If I understand it correctly, going up hill for 5 miles with a 1 mile increase in elevation, would result in an angle of 20 degrees. If the increase were 2.5 miles, the angle would be 45 degrees. I know this isn't quite right since you should compare the horizontal distance, which would be a little less than the diagonal distance, but I suppose for bike angles of climb, that is not a major factor.
But how do you get the percentage of the grade? Isn't that different?