Bicycles are inherently dangerous even in the best of conditions. How many children have skinned their hands and knees while riding in their driveways under their parents' watchful eyes? Thousands. Bicycles should be banned altogether. Skateboards, roller blades, and wagons, too. Public safety trumps recreation, plain and simple.
But let's address the 900 pound gorilla in a speedo: water. People throughout the world are drowning every day. People are drowning while trying to rescue people who are drowning. All activities in, on, or around water must be stopped. This includes swimming, boating, surfing, bathing, and fishing. And frozen water is no better than liquid water. Who hasn't slipped on ice? It's hazardous, and so is snow. The injuries and deaths from skiing, sledding, ice hockey, snowball fights, poor traction, avalanches, and bad glare are limitless. Water in all its forms must be cordoned off from all human contact, except for carefully regulated cooking, drinking, industrial, and agricultural purposes. Public safety trumps recreation, plain and simple.