I rode my MTB last night and I learned something important. I was just riding along the trail, and I saw a pile of 1" thick vines laying there, kinda looking like a pile of snakes - I guess the recent storms snapped them off of a tree, onto the trail.
When you see a pile of vines laying on the ground ahead of you, go around them. Why? Well, when I touched one of them with my front tire, it tipped another one up high enough to lasso my left pedal. I was dashed to the ground, on my right knee, with my bike frame compressed between my right calf and thigh. Think: jack-knife. I kinda sprained my right ankle, and injured my right calf (gave it a spontaneous Charlie Horse, which is still hurting today).
It was like "Top ***", when the F-16 jets land on an aircraft carrier, and the steel braking cable hooks on and brings them to a complete stop. These vines were like braking cables.
So if you ever see vines laying on the ground, think: Pile of snakes! Avoid!