How do people maintain balance while riding a bicycle or skating?

[wangyi]

Hi, I have a question:
How does people keep balance when they riding a bicycle or skating? Moving seems to be essential, when riding a bicycle, we can argue that the wheel is rotating, so it's angular momentum keeps the balance. But in the case of skate, nothing is rotating, but people seem to be able to keep balance better when he is moving forward. How to explain it?

Thank you very much and happy new year!

 

[DM]

Doesn't skating involve horizontal and vertical projections? Isn't the vertical projection independent of the horizontal projection? What about the center of gravity, doesn't it play a pivotal role in the balance of a body?

 

[russ_watters]

With skating, you keep your balance exactly the same as if you are walking - it's just a little tougher because the contact area for each foot is essentially 1-dimensional.