One of Arizona’s most beautiful cities is Sedona, known for its red rock and healthy outdoors lifestyle. But when a pro mountain biker Michal Kollbek visits for a ride on the White Line track, things get interesting. The White Line is No. 6 on the world’s most extreme mountain biking trails, and leaves even the pros shaking. Described as the scariest thing Kollbeck has ever done on a bike, it’s no wonder this track is only for the professional athletes. The track has zero wiggle room on the steep cliff, leaving no room for even the smallest wobble.