Bronze bushes work for bearings (still needs a lathe/ but not ball bearings). Chains can be belts of horsehair (or any civilisation with wire, tube and sheet metal can make a modern chain) or a treadle works okay. Spokes can be wooden.
The main limiting factor is probably the pnuematic tyre and smooth roads.
The main limiting factor is probably the pnuematic tyre and smooth roads.