I don't know what you can do to convince him. Usually when someone wants a bike, there's no convincing them otherwise. However, if it helps him put it in perspective I have my own experience to offer:
My cousin (who I was very close to) was killed a couple years ago. He was on a straight road, slowed down as there were some ducks on the road. Driver behind him wasn't paying attention and bumped him from behind, sending him and his bike onto the other side of the road into oncoming traffic, killing him instantly. If he had been in a car, it would have been a simple fender bender with next to no damage. Witnessing the impact on his parents, his brother and his wife of 2 months was enough for me to decide that bikes weren't for me. His brother still rides, but he takes his bikes to the track and doesn't ride them on the roads due to far too many idiots out there.
Maybe you could convince your son to take it to the track, help support him with that. Get him a car/trailer and encourage that. Might be an expensive outlay, but at least he gets his bike and you can rest knowing that he is in a controlled environment. Good luck, I know that it's a difficult issue.
Last edited by Goondaddy; 01-11-2013 at 05:24 AM.