I never quite understood why it is so much easier to keep a bike balanced while riding at a certain speed, compared to riding it really slow, or while standing…
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When riding, you steer the bicycle back under you. When you’re stationary, you’re unable to steer it back under you so you fall
It also isn’t due to gyroscoptic force alone, and there’s even stable bikes where they canceled out gyroscoptic force
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Roll a coin and it will stay straight as long as it keeps rolling. When the speed reduces, it will eventually topple over. Same with bikes. The rolling wheels help keeping the bike straight up.
Here’s the answer I gave to this question earlier:
There are four major things that keep a bike upright.
One is that the rider on the bike is active, constantly steering to keep the bike beneath them, and constantly adjusting their weight to balance the bike. You can design a bike as you like, and a human rider will be able to learn to ride it.
The second is that the front wheel forks bend forward. This puts weight of the front wheel ahead of the steering pivot. So if the bike leans in one way, the wheel will tend to ‘fall’ in that direction, steering the bike into the lean and correcting it.
The third is that the front wheel’s contact patch is behind the line of the steering pivot. If the bike is pushed sideways, this push will cause the front wheel to steer away, rebalancing it.
These three effects all require the bike to be moving, so the movements of the steering wheel affect the motion of the bike to rebalance it.
And the fourth is a gyroscopic effect on the front wheel. It’s complex, but if you take a wheel spinning on one axis, make it turn in another, the result will be a force 90° later, in the third axis. For a bike’s front wheel, it means if the bike leans in one way, you get a force tuning the front wheel to steer into the lean and counteract it. Like the first three, this needs both a spinning wheel, and a moving bike, for it to work.
Angular momentum of the wheels.
Take a bicycle wheel off the bike and place a handle on the bearing (the point around which it spins), hold it pointing “up”….like a dinner plate. Then start it spinning.
What you will feel is that the faster you spin the wheel, the harder it is to move the wheel in any direction not pointing “up”. The wheel wants to maintain its orientation. The effect is not there when the wheel is not spinning, and the faster the wheel is spinning, the stronger the effect.
Same happens when you’re riding. The faster the wheels are spinning, the more they want to maintain their current orientation.
“Rigidity in space” is a gyroscopic principle that states that a gyroscope (really, anything like a top or a wheel) that is spinning wants to stay in the same plane of rotation. The more a wheel is spinning, the more this principle is in effect.
To really ELI5: the faster a wheel spins, the less it wants to tilt one way or another
Probably, (this is out of top of my head) it’s because the force of moving forward overcomes the force of gravity that would tip you over
You steer the bike to remain under you and balanced without even thinking about it, all other “extra factors” mentioned are wrong or so inconsequential in effect as to be irrelevant.
To prove it try not steering, at all, and see how far you get or better yet just watch this video that explains it much better than anyone so far in this thread….
Look up “counter steering”. in short, if you’re on a moving bike and turn the wheel left, centrifugal force will cause the mass of the bike to go right. Ballance is achieved by constant fine adjustments of turning the wheel one way or the other. on a bicycle, its almost imperceptable. on a heavy motorcycle or when riding agressively, its more noticeable.
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