Why did we wait so long for the bicycle?

Jason Crawford in Roots of Progress:

The bicycle, as we know it today, was not invented until the late 1800s. Yet it was a simple mechanical invention. It would seem to require no brilliant inventive insight, and certainly no scientific background.

Why, then, wasn’t it invented much earlier?

I asked this question on Twitter, and read some discussion on Quora. People proposed many hypotheses, including:

    • Technology factors. Metalworking improved a lot in the 1800s: we got improved iron refining and eventually cheap steel, better processes for shaping metal, and ability to make parts like hollow tubes. Wheel technology improved: wire-spoke (aka tension-spoked) wheels replaced heavier designs; vulcanized rubber (1839) was needed for tires; inflatable tires weren’t invented until 1887. Chains, gears, and ball bearings are all crucial parts that require advanced manufacturing techniques for precision and cost.
    • Design iteration. Early bicycles were inconvenient and dangerous. The first version didn’t even have pedals. Some versions didn’t have steering, and could only be turned by leaning. (!) The famous “penny-farthing” design, with its huge front wheel, made it impossible to balance with your feet, was prone to tipping forward on a hard stop, and generally left the rider high in the air, all of which increased risk of injury. It took decades of iteration to get to a successful bicycle model.

More here.