Though I was usually one for instilling them with independence, I fought Dennis riding his bike to HS. The year that Tim died, he was riding to school 1 day early in the school year, he hit a rock and went flying. His helmet was cracked, but the head was fine. His worst injury was the brake handle that punctured his abdomen. As I was pulling back into garage after moving the car so he could get his bike, I noticed he did not have his helmet on, so I honked and pointed, and he went into the house to retrieve it. 3 months later he was a pedestrian struck by a car and killed. Ironically, there was no damage from the car, but his head hitting the road was fatal. Had he had a helmet on, he might have survived. But a parent can't really make a child walk around wearing his helmet all day.
Letting go, in any way, shape or form, is hard.