When freewheeling on a bicycle, why is no effort required to remain upright?

Question

If a dummy of similar weight to me were substituted, the bike would keel over and yet no discernable effort is made on my part to keep balance. One of those physics questions that has always puzzled me.

Answer 1

What a good question! I was going to answer 'because of the conservation of angular momentum', until I read the second part of your question.
"New Scientist" magazine a few months ago published an answer in its 'last word' (similar to Yahoo, where readers send in questions to be answered by other readers.)
New Scientist explained that riding a bicycle involves not only angular momentum, but the gyroscopic effcet as well. Someone had even designed a bicycle that counteracted the gyroscopic effect, which was very difficult to ride.

I think the answer to your question is that we learn to naturally place our centre of gravity over the axes of the bicycles, and do this without thinking. (This can be understood, when we think how hard it was to ride a bicycle when we were first learning; and to start, we fared not much better than a crash dummy, at our first attempts). As the saying goes, 'its like learning to ride a bicycle' (something learnt once that is never forgotten.)
It all has to do with our inner ear canals, and our innate propriocentric (positioning) reflexes.

Answer 2

A dummy does not balance. Just like if you put a child on a bike he or she falls down. Freewheeling is the same as pedeling. It requires balance. Equal balance on on each side and other factors needed for balance is necessary. A dummy simply can't do that.

Answer 3

The key word is discernible. Your autonomous nervous system is trained to handle this. If you see or feel yourself starting to lean to the left, you automatically turn the handlebars slightly to the left. That tends to start moving the front wheel, then the rest of the bike, to the left, and again under your center of mass. The gyroscope effect is very small compared to this.

Answer 4

You maintain, by brain-science not yet clearly identified, a sense of equalibrium. This would happen even if you were in a coma. The brain combines the gyroscopic effect of the wheels with it's own ability to keep you "straight"... I'm currently a member of a group of scientists to figure out how this works. It relates to how a legal drunk makes his way home, without knowing how.

Answer 5

Dead weight on a moving bicycle would continue to move forward in an upright position, unless the dead weight couldn't re-balance the machine after hitting a bump.

Bicycles work on the basis of gyroscopic stability, and are perfect lessons in Newtonian mechanics.

Answer 6

The spinning wheels have a gyroscopic effect which helps keep the bike upright
even though you think you aren't doing anything you still subconsiously react to imperfections in the road or wind etc.
the dummy is on his face as soon as he hits a pebble.

Answer 7

i would say its a combination of your balance and the wheels acting as a gyroscope to keep the bike upright and going in a straight line,this is best evidenced when turning because you have to automaticaly it seems lean over to remain stable

Answer 8

i think subconsciously, your still maintaning balance. if you feel yourself tilt one way, you correct it, without thinking. a dummy starts falling and just keeps falling. You would do the same thing if you stopped pedalling and just sat there, and did not move your body at all.

Answer 9

you are making an effort to stabilize yourself but the actions are so automatic you don't realize, more biology than physics

Answer 10

All I know is if I tried that, I'd fall flat on my face.