I figured it out all on my own – I am good at this physics stuff 🙂 If you hold the bike wheel still and tilt it so the part moves left at the top part moves right. Take a particular chunk of mass at the bottom, it has momentum to the left. If the wheel is rotating, however, that same chunk still has momentum to the left when it’s at the top, which means it’s now opposing your tilt. So all the force you put into tilting it ends up opposing the tilting force a short time later.

The faster you spin it, the shorter that time lag is so the better it works. This also explains why you can get it to oscillate if you wiggle the wheel side to side at the right frequency. That frequency matches the angular momentum of the wheel. Hence speed wobble on motorbikes, I suspect.

The gross and net result of it is that people who spent most of their natural lives riding iron bicycles over the rocky roadsteads of this parish get their personalities mixed up with the personalities of their bicycle as a result of the interchanging of the atoms of each of them and you would be surprised at the number of people in these parts who are nearly half people and half bicycles…when a man lets things go so far that he is more than half a bicycle, you will not see him so much because he spends a lot of his time leaning with one elbow on walls or standing propped by one foot at kerbstones.

You never see them moving by themselves but you meet them in the least accountable places unexpectedly. Did you never see a bicycle leaning against the dresser of a warm kitchen when it is pouring outside? Near enough the family to hear the conversation? Not a thousand miles from where they keep the eatables?