Diversification Old & New

I know weird when I see it, & I don’t mind Bobbers, choppers are bit past the post though, my roots lie in cafe-racers but would you say the Indian on the left is a chopper or something else, never mind if this chap turned up on a Association ride we would welcome him, “a Indian is a Indian” end of story. The trike on the right is a period machine built in the teens, close to 100 years before the current rash of trikes from Vespa, only thing new in motorcycle is probably electronics, a small quiz though for the more studious among us What is fitted to every vehicle since 1900 that still directly interchanges & is fitted to every vehicle on the road today? For Members the answer is in the Members Area for the rest of you I will give  the answer in a week.