I am all for going fast on a machine designed to go fast as much as anyone else. But bicycles were never designed to go 50 mph. If Mr Kenard had only a minor mishap doing that speed, he should count himself lucky. If he insists on going fast, I hope you can convince him to wear a full helmet, leather gloves and lots of padding. Maybe get a real motorcycle. I am going to guess his tires deformed and got caught in the frame. I have been in many bicycle shops. Maybe they will lace a wheel with 12 gauge spokes. Certainly get tires designed for high loads and high speeds. I have Panaracer street tires (no, they are not racing tires). Speed costs money. I don't intend to come across as negative, but I encourage you to convince him to keep his speed down. Only at a race track does a rider get an award for being the fastest. Best of riding to you and him.