When a bike and rider are zipping merrily along, the mystery is that they seem to stay upright with relative ease, but common sense surely tells us that if nothing tangible is holding the bike and rider up — it must be quite possible that they could fall down? That makes sense now, doesn’t it?
In the process of learning to ride a bike, intangible matters such as faith and belief arise, as well as stability and balance in a metaphorical sense.
C. S. Lewis (1944) wrote in Perelandra, page 68, “There is no reason why a man on a smooth road should lose his balance on a bicycle; but he could.”
Our point is that there is a certain mystery about a bike. It seems to be so stable remaining upright, and yet common sense, if we actually examine matters, tells us that nothing visible seems to be holding the bike up. If nothing visible is holding the bike up, then it seems obvious that it might fall — unless we start to believe in the power of the invisible.