I fondly remember stripping one of those down and rebuilding it with my Dad when I was about 12.
Sorcha, I really and unconditionally empathise with you and your son on this and wish him a speedy recovery. Luckily, although I have been a biker for 33+ years, I never had a spill or an accident and tend to agree with Egal on this. According to my insurance broker, 90% of all bike accidents are caused by careless car drivers.