Gyroscopic stability is a natural phenomenon where the center of gravity can balance over a moving wheel, and the wheel does not fall over. Essentially, it’s just a fancy way of explaining how bikes balance as we ride.
Making minor corrections to keep your weight centered is a learned skill. How do bicycles stay upright?
Bicycles stay upright because of gyroscopic stability, which is a wheels’ tendency to try and remain vertical while in a state of vertical motion. With the help of a rider, balancing the weight of a bike and person over wheels is easier because people do the corrections manually. However, a moving wheel that starts to tilt may also self-correct.
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Why Do Bikes Stay Upright
Bicycles don’t just ‘magically’ stand up on their own. Even the best bikes need a kickstand or other brace when they’re at rest, but it’s a whole different story when they are in motion.
The balance of these incredible human-powered machines can seem confusing at first, and we only know part of the science behind why bikes stay upright.
Additionally, the person riding the bike has a lot of control over where the balance is over a bicycle’s wheels.
Suppose you shift your weight too far as you lean to one side without correcting quickly. You will fall.
Likewise, a slippery road can cause an unintentional shift that happens too fast for recovery. So, the ability to maintain an upright position is limited.
What Keeps A Bike Upright
A brace like a kickstand keeps a stationary bike upright and balanced. The wheels form two points of a tripod, while the third brace offers stability that two movable round ‘legs’ cannot manage on their own.
A bike in motion is kept upright by centering your mass over the wheels and maintaining enough speed and control to create a gyroscopic precession.
How Do Bicycles Balance
A bicycle needs the center of gravity over the wheels to balance correctly. Then it needs gyroscopic procession in order to keep moving forward.
Unfortunately, it also needs to be going fast enough for the gyroscopic stability to take effect before the bike tips too far to one side and falls.
A bicycle moving too fast can also fall because small variables in the road or minute movements from the rider causing instability that shifts too quickly for a normal reaction to help correct the problem.
You need a precise combination of balance, speed, weight distribution, and gyroscopic stability to balance in motion.
The ideal riding speed varies, and as Bike Radar says, “There’s no ‘perfect’ cadence, but trained amateur riders typically ride at around 80 to 90rpm…”
Depending on your tire size, that is usually around 10 to 15 miles per hour.
How Does A Bicycle Work Physics
A standard bicycle has a backward tilted steering axis. Your leading tire touches the ground slightly behind that axis.
This design, when combined with the gyroscopic procession from the wheels, assists you and the bike in maintaining the center of gravity where it should be.
In short, the way your bike is designed forces the cycle to turn as it tilts, which changes the center of gravity back to where it should be.
Notably, not every bike has this same design, so other configurations can also help force a bicycle to conform with that natural tendency for gyroscopic stability.
Adding a little weight in the wrong area can destabilize a bike making it more difficult for a rider to keep the center of mass over the wheels and forcing them to lean to stay upright, which unbalances the rider.
I recommend checking out this video from Minute Physics for a visual demonstration of how bikes work and balance.
They explain that you need more than one force to keep a bicycle upright and show you how it works together.
Why Does A Bicycle Stay Upright When It’s Moving But Falls When It Stops
The gyroscopic effect of moving wheels is that they tend to continue in the direction naturally, and at the angle, they were already moving.
So long as the wheels on a bike turn, they are capable of minor self-correction that causes the center of mass to stay centered.
However, the same rules do not apply without motion, and a bike is subject to the same sorts of physics as a rock or tree.
Since bikes are imperfectly balanced, and there are variations in the ground, tires, and even wind, a bike doesn’t stand there on its own.
However, if you were on the moon, the bike would stand up fine without a kickstand. There is less gravity to pull the meal downward on the moon, and no atmosphere, which means no wind.
Once the bike was balanced, it would stand there basically forever without moving.
A bicycle in motion will often lean to one side, but it will also turn to that side as it tilts. Doing this causes the wheels to stabilize under the center of mass, and the bike will continue to move forward on its own.
In order for that steering to be effective, the bike has to be moving. Otherwise, the handlebars moving side to side would unbalance the bicycle.
Why Is It Easier To Keep Your Balance On A Moving Bicycle Then On A Bicycle At Rest
A bicycle in motion has the added advantage of gyroscopic stability. However, a non-moving bike is just a weird shape on two rounded legs.
Without that forward motion, there’s no reason for the bike to stay upright, and it requires a kickstand or someone with good balance to maintain that vertical alignment.
The weight on top of a bike where the seat, toptube, and handlebars sit is drawn toward the ground. It’s natural for gravity to pull things down, especially if they aren’t balanced or braced in place.
Plus, round wheels are a terrible base if you want static stability because they tend to move around the axis.
Helpful Tips To Know About How Bicycles Stay Upright
Bicycles need a combination of proper design, weight balance, and gyroscopic procession to move forward without falling over. If that sounds complicated, it is.
Here are more helpful tips to know about how bicycles stay upright.
- The weight of a bike’s front wheel, fork, and handlebars are almost always distributed in front o the steering axis. This downward pull helps the cycle turn toward its center of gravity when it moves off-center.
- If you push a bicycle backward, it will fall very quickly. This is because moving back reverses the gyroscopic motion, but it changes the ‘setup’ and balance of the bike with respect to its direction of movement. That means the bicycle no longer self-corrects, and it’s harder for a rider to balance.
- Everything we know about how bicycles balance helps, but it’s an imperfect understanding. The way different bicycles balance is still a mystery because no one knows exactly how much of each force acting on a bike it will take to create a perfectly balanced bike. Design and weight variables have not been fully explored, so there’s still more to discover about how a bike stays upright.
As you learn to ride a bike and gain more confidence, you’ll notice that the bicycle seems to want to stay upright, and it’s just the inexperience and lack of balance in the rider that caused accidents.
Thanks to gyroscopic stability, a moving wheel tends to self-correct and stay balanced. Once you add a bike frame and a person on top, it gets a little more challenging because of the weight distribution.
Fortunately, humans are masters at balancing. After all, we learned to walk upright without the aid of a tail to counterbalance our bodies, so shifting your weight over a bike is no big deal.