[jmopp]

The bicycles that were made from wood and iron gave an extremely stiff ride and were called boneshakers.

[Ekaros]

At time when roads were not what they are these days. Lot of their improvement before cars became from bicycles.

[Lio]

There's a good book about that very subject, The Roads Were Not Made For Cars[1].

https://roadswerenotbuiltforcars.com/

[kgabis]

I think pneumatic tires are the single most important invention when it comes to making bicycles comfortable and allowing smaller wheel sizes.