system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Wheels, wagons, and chariots were invented thousands of years ago. Why, then, did it take all the way until the 1800s for the bicycle to make its debut?
gpt
Materials, manufacturing techniques, and road conditions.

We had to reach a point where metallurgy and materials made a bicycle beneficial. You can make a bike out of wood and metal, but its gonna be extremely heavy, prone to breaking, and difficult to ride. Without extremely smooth solid roads you would be slamming and jarring the wheels and frame constantly.