My corner of Rhode Island is relatively flat but not dead flat. Few hills here are very long, (one mile max) or very steep, (8% to 10% max). I divert from regular routes to ride some of these hills when they are close. One hill goes up to a bluff overlooking a river and is much steeper than most but no longer than, say 1/4 mile. After getting lower gears on the bike of 23 gear inches, I gave it a go. I made it but was very glad to see the top.
Some weeks later, out of curiosity, I made a protractor like device, used with a carpenters pocked level to measure the slope. Standing at the top and looking down it feels like standing on the rim of the Grand Canyon staring into vast depths. I was very disappointed to measure a mostly 12% slope with a short roll at 13%. I've come to believe that those who claim climbs of 18% of 22% should have their mouths washed out with soap. I wish now I'd never measured it - ruined an epic tale.