What did people ride for cold weather cycling "back in the day?" (Is it cheap?) Everyone who has ridden a bike any real distance in the cold has likely noticed a few things.  Due to the speed to effort ratio of the bicycle, certain thermal realities have different relationships than they do on foot.  

For example; a cyclist who is going up a hill can easily become hot and sweaty in clothing that would not sufficiently protect a sedentary person from the cold.  If, however, they were to go down a hill shortly thereafter, they might find themselves facing an improbable gust of wind... with increasingly wet clothing from the prior effort.

To say nothing of if such a poorly protected cyclist were to start by coasting downhill in clothing insufficient to... either way welcome to my commute.

Now, there seems to be a vast array of, well, fiber technology meant to protect someone in just this scenario.  I found that even wearing a $10 jogging undershirt made a huge difference over cotton.  ("Cotton kills" as the boy scouts say.)

But that segue into my question: what exactly were people doing BEFORE spandex (aka lycra) and other synthetic fibers?

If you believe the industry, you'd think you HAVE to have the more advanced stuff, but I doubt that people just stopped riding in the winter before it was invented... or did they?

(And can I avoid buying any kit by imitating them?)
Wool, wool, and wool. Wool undergarments. Wool over garments. (Maybe tweed as well.) Wool is a amazing material. It tends to perform better than synthetics (although the gap is closing) for keeping you warm when it is wet and cold outside.

On descents people also used to just either tough it out or did life hacks such as putting newspaper down the front of the jersey rather than rely on fancy rain shells.

Now here is the caveat about wool and the old world approach. Real wool garments are often much more expensive than equivalent synthetic garments. So from this perspective synthetics are a much better choice than killer cotton if you cannot afford wool. Synthetics also tend to wear a bit harder and typically don't need to be hand washed, so wool is more care. You typically only had a few garments which you washed by hand at night before the next day of riding. You also had to learn how to darn wool, so you could fix damage that can happen to wool over time.

Synthetics dominate today because of the cost, reduced care and good enough performance.