I usually map my rides with ridewithgps or mapmyride, in order to get a good estimate of the grades. Now that iphones have level apps, I decided to check a few spots on my usual loop, driving the route and stopping to check the grade at the steeper points.
The steepest parts of the hills that ridewithgps says are 20 plus % are reading 8 to 10 degrees on the phone and that translates to 14 to 18 %. So it's steep, but not as steep as I thought!
Just thought I'd mention the discrepancy for anyone else using the programs.