once was riding through a busy street (Nevskiy prospect). Everything was good untill i saw a strange guy. Probably he hated all cyclists, but anyway....he hit me in my shoulder real hard and i wall down. As my speed was pretty high, i slided on the ground and hit the nearby summer caffe fence with my head.....thank god i was wearing a helmet. I stood up and my head was going round a bit...i sat down and was sitting for about 3 mins and only after that i could stand up. That guy escaped(and was lucky because otherwise i'd have beaten him hard!_)