Only 50% if you count walking around carrying a table as 100% the same as just walking :) That said, my non-expert opinion is that a penny-farthing without bal

Only 50% if you count walking around carrying a table as 100% the same as just walking :) That said, my non-expert opinion is that a penny-farthing without ball-bearings would probably still work OK; a rover-style bike with a chain would be much harder. But the ability to make bicycle chain, and the ability to make spokes for wheels, I think these happened about the same time too.