Literature professor = bike argument?

That's were I put my money, but I could see it going either way.

This can devolve into a definitional argument, but I actually think it's fair to say we don't understand how we ride a bike. We have many abilities and fluencies we don't understand, or only partially understand, in the sense that we can't break them down into pieces easily and transmit the information. That perspective feels more accurate to me than saying I understand how I ride a bike because I can ride a bike, though in common usage the phrase "I understand how to ride a bike" would be perfectly acceptable.

The subtle distinction between the phrase "knows how to" and "understands" hints at the difference here.