I think the the only way to secure accurate gradient information on Brasstown Bald, Spur 180, is to put out a surveyor and assistant at each tenth of a mile and record the result. There are lots of first person accounts on the internet, but too much variation. The average grade is somewhere between 10 and 12 percent, and 2/10 into it is a 16% grade and 5/10 has the first 20% ramp. "The wall" comes around 1.5 and could be as low as 21% or high as 26% depending on whose data you want to use. I saw 24% on my Garmin 305 this year, and 24% on my Garmin Forerunner 201 in previous years, so I'm comfortable using that figure. If it really is only 22%, it's still steep, especially after a mile and a half of hard climbing. There is another 16% ramp slightly over 2 miles. One report has percentages every .05 but that gets skewed. You can tell when you see the 45% on one leg. Of course, that might be correct if you take that right-hand bend on the inside, because for about twenty feet it is real steep. If you take the outside, you miss about half the climb.
The first year we did this, we got a ride to the top of Wolf Pen Gap, then let gravity take us, generally, about eight miles, or to the bottom of the climb up to Spur 180. The climb turned out to be about five miles of hard labor, robbing us of a lot of leg and cardio strength.