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On a frictionless road and tires, I know the rider wouldn't be able to change the combined center of gravity of the system by moving his weight around. If he pushes the bike to lean to the right, he would go to the left by the amount that would keep the combined cog the same. But a bike with real tires and a real road under it is not a closed system, the tires wouldn't let the lower part of the bike left or right when trying to initiate lean.

Does this mean it is possible to push with your bodies inertia to the bike, and the combined cog will be changed?

I think if you do so below the center of mass of the bike, you could, but I am not sure, since the tires will want to move more, but won't be able to, making the combined center of gravity shift more than if you applied the force higher up. And I think you should use horizontal forces on the pegs not up/down forces on the pegs

I know counter steering is the best way, but I would like to think it is possible to change direction without it, without the influence of handlebars

Please ignore gyroscopical forces and assume the bike doesn't have any trail geometry (so you would have to "catch" the bike manually through the handlebars)

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marked as duplicate by John Rennie newtonian-mechanics Oct 8 '17 at 7:12

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • $\begingroup$ Please state in one sentence what your question is. $\endgroup$ – Lambda Oct 8 '17 at 5:44
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Yes, this is possible. In fact, professional trick riders do this all the time. You have to do it when popping a wheelie. Now as a motorcyclist, I'd be remiss if I didn't point out that this is dangerous, but it's certainly not a physical impossibility.

If you think about the physics of a wheelie, the rider can use the throttle to control the angle of the bike up and down, but they have no way to control left and right using the handlebars (since the front wheel is in the air). The only way they can keep the bike moving down the road in a straight line is to make micro-adjustments to the left or right to lean the bike in the direction they want it to go. In fact, they can even go around corners like that!

Also, while it isn't exactly your question, I'd recommend the Smarter Every Day video on how cats land on their feet. It's an excellent exercise in physics in action!

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