Good steel would only be strictly needed for axles.
Bearings could have been polished and oiled wood. The frame, wood. The hinge of the front wheel, brass or another small bit of steel. Transmission could be a leather belt. Wheels, wood again.
Would such a device somehow emulate a modern bicycle? Very likely.
Would such a device be practical, reliable, fast, to say nothing of comfort? I greatly doubt it.
Bearings could have been polished and oiled wood. The frame, wood. The hinge of the front wheel, brass or another small bit of steel. Transmission could be a leather belt. Wheels, wood again.
Would such a device somehow emulate a modern bicycle? Very likely.
Would such a device be practical, reliable, fast, to say nothing of comfort? I greatly doubt it.