1886 HH&C safety.
The prototype bicycle, basically.
I'll post a resto thread when we get on to it, but given it sat in a barn for 50 years, one of my colleagues took it for a testride with almost no repair:
The cross frame replaced by the double triangle, the pneumatic tyre, the freewheel.
Millions of riders thinking about this revolutionary bicycle moved it from a toy to what it is today in about 2 years. Hive mind.