A (nice) story about a kettenrad in 1980, a dealer-collector in the north of the Netherlands had one but was missing some running wheels an other guy had plenty but didn't want to sell only buy his, the dealer got mad, took his maschine apart and thrown all parts separate in his huge pile of parts with lanes over the parts you where walking on kettenrad parts.
He is a nice guy, still alive and regulary on Dutch television when he is skating as first on new natural ice.
He also bought hundreds of war BSA's from a Arabian dessert and 25 Nortons 16H's wich where used for learning the English soldiers in Arabia, he sold them all before the containers arrived unseen !!! the buyers later found out they where all cut open, even the oil and petrol tank
I also bought one for 100? pounds