Long before bicycles, people observed that rolling wheels (e.g. coins) are stable above a certain speed, falling over when they slow down.
(This is actually true of bicycles, for a similar reason: like a single wheel, they steer in the direction of a fall, and that counteracts the fall, because if you steer left, you fall right and vice versa.)
The possibility that a two-wheeled vehicle could be stable when moving should have manifested itself to some of the brightest minds in European science as far back as at least the Renaissance.
most of the mystery disappears as one notices the absence of good quality roads and low-friction (fine) mechanics (as both are hard requirements for an "economical" human-powered vehicles - as even untrained everyday folks are relatively good at endurance running/walking and carrying a light backpack, but carrying ourselves plus a vehicle over bad terrain makes it not worth it)
we like to think how amazing the wheel is, but ... what's amazing is a road network. and what's ridiculous is that some empires spent their might on making flat slabs and putting them in a big pile, while others used some of theirs to make roads, but it took so many years to combine the two :)
and that's why railroads appeared before bicycles basically.
> The hard, flat road surfaces we take for granted are relatively new. Asphalt surfaces weren't widespread until the 1930s. So, are motorists to thank for this smoothness?
> No. The improvement of roads was first lobbied for – and paid for – by cycling organisations.
Good roads are important to cycling, obviously, and to cycling becoming popular, but lack of smooth roads didn't impede the development of the bicycle. Rather, lack of bicycles impeded the development of smooth roads!
(This is actually true of bicycles, for a similar reason: like a single wheel, they steer in the direction of a fall, and that counteracts the fall, because if you steer left, you fall right and vice versa.)
The possibility that a two-wheeled vehicle could be stable when moving should have manifested itself to some of the brightest minds in European science as far back as at least the Renaissance.