Captain Bb wrote: until decending a particularly steep hill one day when mine became unstable at speed and threw me over the top.
This happened to me twice going down Totnes bypass. I was about 8 at the time. Bombing down this long hill I got a speed wobble fell off, I picked myself up, everything seemed ok so I carried on. Then it happened again, this time in front of a landrover, he stopped picked me up put my bike in the back and took me home. My mum told me that the guy said "buy him a proper bike".
I never rode that bike again, but I did have one in my teens that I never had a problem with.