I would say that if you can't explain on a blackboard how to ride a bicycle, then that simply means you do not understand how to ride a bicycle. You can do a th

I would say that if you can't explain on a blackboard how to ride a bicycle, then that simply means you do not understand how to ride a bicycle. You can do a thing without understanding it. I would guess very few bike riders really understand what all makes the act work even though they all can perform the act. Maybe no one can learn how to ride a bike purely from a blackboard but that is a seperat issue about physicality. But the quote is really about understanding, and the forces and effects that go into the act of riding a bike are both understandable and explicable. Anyone who understands them can describe them on a blackboard. So the quote holds water even in the case of riding a bike. I would say anyway. Maybe there are other examples and bike riding just wasn't the best example to invalidate the quote.