Trailer hitches poorly copied from the winchester clamp and rendered in substandard materials do not attach very securely to modern alu frame stays. In fact they fall off. They are not safe. QUOTE]
My £60
eBay special had a clamp-based hitch, and I quite agree that they aren't safe. Granted, my son lost the tightening nut, and I had to replace it with a large wing-nut, but even tightening the nut as hard as I could with a pair of pliers, the grip on the hitch still wasn't that great. The hitch came off twice when I was towing my son - both times the failsafe leash prevented the trailer from careening off down the hill behind me, but both times the hitch got twisted up in the spokes of my rear wheel with a sickening crunching noise, requiring the wheel to be serviced each time.
I feel much safer with the carryfreedom hitch fitted.