The GAP is actually a very well-maintained and fairly smooth (for limestone) path. Dusty, as someone said, but a nice surface for 1.25-1.5 inch tires. A heavy rain could give it some rills, but a light rains is just soaked up by the crushed stone. I rode it a few years ago. The grading is so gradual you'll hardly notice the uphill to the divide heading east, though you get a nice downhill run after the divide.