I had one last week. It was raining and cold. I was commuting to work and crossing the Brooklyn Bridge on a bike path with a walk lane. The entire section is made of wood. I was trying to dodge some pedestrians by shifting weight and leaning. Leaning is not good on wet wood that I found out. I rode a 28lb MTB with semi street tires. Basically, the side of the tires with knobies took the full weight. I lost traction. I went down side way (right side) HARD and ending up sliding for some 10 feet. My right hip took the full impact and I brusied some muscle. I was going about 18 mph or so.