Had my first major accident after 20 some years of serious riding. Was on a bike trail on a wooden bridge. The bike just went out from underneath me. The pavement was wet, although I frequently ride on this trail when it is wet. A guy I was riding with, when I fell, tapped his brakes to begin stopping. He, too, fell. I hurt myself more--shoulder and upper leg swelling and pain. I hope the shoulder is going to be all right. X-rays showed no bones broken. The guy I was riding with said that the area where we fell was like ice. What could have caused this? don't think I will be back on the bike for a while. Don't want others to experience what I did.