This is not quite true, though it would be very funny if it was.
The classic "old bicycle" we're all thinking of, which looked like this:
Is actually a technological compromise developed in the early 1870s. The very first bicycle was invented in 1817 and it looked like this:
It had no pedals and the rider would push it along with their feet, the same way toddlers learn to ride bikes today.
In about 1864, a mechanic in france came up with the idea of adding pedals to the front wheel, making the first self-propelled bicycle.
This was a great improvement because it's a lot easier to move and a lot more fun than the Fisher Price version above. It was a big thing for about five years, but there were some drawbacks.
First, because the pedals were directly attached to the front wheel, you couldn't go very fast without moving your legs incredibly quickly, which takes a lot of effort. It also is kind of awkward to steer because your legs are in the way of the wheel.
The other issue was bumps. Roads were not very smooth in the 1870s, most of them were unpaved and full of ruts, potholes, and rocks. And at first there were no rubber tires, just wooden wheels with metal rims. Altogether this made for a very bumpy ride.
The big front wheel, which was made possible by the invention of wire spokes and solid rubber tires, solved all of these problems. A big wheel runs over bumps more easily: think of how rough it is to ride roller skates over bumps in a sidewalk that you would hardly notice on a bike. And the bigger the wheel, the faster you can move with one push of the pedals. Having the seat on top of the wheel, instead of behind, also makes steering less cumbersome.
There are of course drawbacks to this design, in particular being so high up makes it very easy to go over the handlebars if you crash, and more likely to hit your head or break your arm.
Two more inventions helped drive this comical beast into extinction and bring back a more balanced, and safer, bicycle.
The first was the pneumatic tire, which contains a cushion of air, and makes for a much softer ride compared to a solid tire or a metal one. The cushion effect eliminates the need for a big wheel to smooth out the bumps in the road.
The second invention was the sprocket and chain drive. This lets you put the pedals anywhere you want on the bike, and with a big gear at the pedals and a small one at the wheel, you can get more speed out of a small wheel.
The first modern bicycle to combine a sprocket and pneumatic tires was built in 1879. It was an instant hit, not just because it was much less dangerous, but because the low drag profile and the smooth pneumatic tires made for a faster ride, and the trendsetters in cycling, then as now, were the racing community. There have been plenty of innovations and modifications in the years since, from ten-speed gears to carbon fiber frames, but these are all variations on a theme. The basic form of the bicycle has not changed.
