I was coming down a hill that is very fast like 40-50, my fastest run being 49 at top speed. I took the right lane as I thought to let a car go by in case they were speeding and tried to flatten me out. First time BOOM almost got dismounted from the pop up of hitting what must have been a 3-5 inch tree root that was hidden by the shade of the tree. Another time I was going down the same hill and had the rear tire flat....thank God it was the rear, got the bike slowed down and too the side. This did not change the my mind, just made me notice.