How Does A Bicycle Balance?

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Speaker 1: Hey, orror, Hey, what image do you get in your mind if I say the phrase mysteries of the universe? I think I think of you know, black holes and what's inside of them, and what happened at the beginning of time and where is the universe going to go? Those are all wonderful mysteries, and I'd love to dig into them. But what if I told you you don't have to go so far away to find mysteries. M You mean, like, why is a cartoonists hosting a podcast about science? Yeah, that's exactly the point. It turns out that there are deep unanswered physics questions all around us. You don't have to travel to the edge of the galaxy to find something we don't understand. Yeah, I've heard about this that in the objects we use every day there might be things that even physicists don't know how it works. Yeah, it turns out physicists don't know what we're talking about all the time, but you don't know what you're talking about, or you know what you're talking about, but you don't understand. No, that's the exact job of physics is to look around us and say, do we really know how this works? Can we actually understand it, and sometimes we think it's a simple explanation, but we sit down to work it out and it turns out it's much more complicated than we thought. Yeah, it turns out there are big mysteries even in the things that a lot of us ride to work every day. That's right. I'm and I'm Daniel, and welcome to our podcast Daniel and Jorge Explain the Universe, a production of I Heart Radio, in which we look around for weird things in the universe that don't make sense and try to explain them to you. Sometimes we look far, sometimes we look pretty close to home. That's right. Today in the episod, we're going to try something a little bit different. So usually we talk about the big things out there in the universe, all the big fundamental questions about what the universe is made out of and where's it going and what happens inside of crazy things like black holes. But today we're going to try something a little different. That's right. Some of those are big sexy questions that affect the human condition and the context of your life. But we think sometimes there are mysteries of physics right here in front of us that can give us deep insights into the way things work and how we live our lives. So this might be the first of a series of episodes in which we tackle a question that's kind of close to us or in maybe hidden in everyday objects. That's right, So look around you think about whether you understand the way the world works around you. Why doesn't your house fall down? How do the lightning rods work? All these things that are happening around you. Do you really know how they work? Do physicists even know how they work? So today on the podcast, we're going to talk about why don't bicycles fall over? You know, the bicycle has been around for a long time. People have been putting their butts on those funny seats and peddling around for decades and decades and decades. But the physics of a bicycle is fascinating. If you just hold a bicycle and let go, it's going to fall over, right, But if you push your bicycle so that's going fast, it doesn't fall over. It can ride by itself. It's kind of a ridiculous situation. Do you think about it? Like? Who thought it to take two wheels and right around and in them? That's right? It seems like it wouldn't balance, right. It seems much more natural to have three wheels or four wheels. Right. Maybe somebody was just short of wheels and they were like, dang it, I ordered three wheels on the internet, only to arrive. I guess I'm gonna have to invent something. They couldn't aford a third wheel only they only had the raw materials enough for two wheels or something. You were like inventing a new myth of the genesis of the bicycle, right, Yeah, well it seems implausible because it's hard to balance, right. You need at least, you know, like a chair needs at least three legs to stand on. It's kind of weird to think that someone would think of a vehicle that only rides on two wheels. Yeah, that's right. Not many people invent chairs with just two legs, right, for that same reason. That would be pretty odd. Um. Yeah, there's so there's two wheels, all these two wheel contraptions. We have motorcycles, we have bicycles. It is amazing. It's not something that I would have considered inventing, but it works. You see bikes everywhere, and you go to Europe and India, and China, and there's all over the world. There's thousands and millions and millions of bicycles being used every day, but the physics of it is still a bit of a mystery. Yeah, how do bicycles stay up? Apparently physicists don't really have a good answer, right, yeah, that's right, Um, it's it's fascinating. But you know, do this experiment in your head. You remember riding a bike, probably, and it's the faster you go, the more stable the bike. Seems that at some point you could even lean back and take your hands off the handlebars, and it seems like a ridiculous thing to do. You're going twenty miles an hour and if the if the handlebars flipped over, you would fly over the front of the bike. You can hurt yourself. But miraculously, almost it seems pretty stable. And I remember discovering this as a kid, that you could ride your bike without holding onto the handlebars because at high speeds it's so stable. Yeah, wearing a helmet though, right, we should probably wearing a helmet, and it's only you know, off the street. Of course, never ride with without holding the handlebars on the street because you could cause an accident or or okay, that's right. Actually, my dad used to commute to work on a bicycle, and we lived up in the mountains in New Mexico, and so he could get pretty snowy, and I remember that he would put um nails and studs in his wheels on purpose, like sticking out so that he could grip the ice. Yeah, he was a pretty hardcore commute commute to work. He was like, I'm going to commute to work no matter what the weather is. Sounds like a Matt Mag's modification there. Yeah. I asked him once if it was good for the ice, and he said, actually, it's pretty good for pedestrians too. Let's getting for clearing the road on pedescans exactly exactly. Um, yeah, so we understand that, but we don't understand why bikes stand up. Yeah, it's kind of a mystery. You write it, and uh, I mean you do. You're doing a lot of the balancing with your handlebars, right, But a lot of the balancing and staying up is kind of done for you when you're riding a bicycle. Yeah, that's right. A lot of it is done for you. And I think there's also a fascinating area there where your brain has like incorporated the mechanics of a bicycle into your into itself. Right. It's like learning how to ride a bike is basically learning how to map where you want the bike to go to, how to how to move your hands and shift your weight, etcetera to ride the bike. Right. It's amazing seeing seeing a kid learn to do that. It's really complicated thing. Like imagine a robot learning to ride a bicycle. That's a really hard task. That's something that robots still can't do because it's very counterintuitive, right to ride a bicycle. Yeah, that's right. I mean like if you're starting to into the right, then you actually you'll have to teach your body to turn the wheel towards the right to balance, Yeah, exactly, And you have to lean the just the right way, and sometimes you have to lean left to turn right. You can get pretty complicated. Um. It's sort of in its most extreme form in those crazy motorcycle races. You see those guys whizzing around turns like a hundred something miles an hour and their bikes are leaning so far over that their knees almost scrape the ground. Right. But basically, if you're at home, and maybe you don't have a lot of experience of bicycles and trying this experiment at home. Borrow a bicycle or if you have one, take it out and then hold it out either on the street or on the sidewalk, or maybe ideally kind of in a little bit of a downhill, and then just give it a big push forward and you'll see that the bike keeps going straight. It doesn't immediately fall over exactly. And so that's the topic we want to address today. Why does the bike stay up? And so before we dug into it, I thought, well, let's find out what people think. Let's see what people think the answer might be. Yeah, so you went to your local mecca of bicycles right at college campus. That's right, that's right, and asked people on the street. Actually, today's a sort of a special edition because this quarter at you see Irvine, I'm teaching freshman physics, which is mechanics, And the week before we did these interviews, I just taught about rotation incular momentum, and so my students were primed for this topic, and so I asked students in my freshman physics class this question. So the interviews you'll hear are with students in my class. Cool. So think for a moment and if you think you know the answer why a bicycle stays upright? So think about it for a second and then listen to these answers. Here's what they had to say. Why does a bicycle balance? Oh, you have to get the motion going. You gotta get you know, centrifugal forces. You gotta get your back are your physics professor, And definitely not. Would it be because since there's two wheels like the force, and one goes to thegether, that's why it still keeps going forward. Something like that. Okay, thanks, umws. There's a talk from the tire um way we're rotated, the talk of support the rotation. It's sort okay because it's is it because it's moving? Chance because like a loane like standing up and want it. They want to like stand up by itself. So I'm not sure. Actually I'm not exactly sure, but I'm thinking it has something to do with maybe cent tripital forces. The fact that there's constantly like pushing in or like towards the center of the bicycle wheels, so as opposed to where it's not rotating. It's kind of unstable because it doesn't have any like other points of contact. I think that this has to do with either the angular momentum or rotational inertia the bi So if something is rotating like a gyroscope, because of its angular momentum, you will continue to rotate more easily rather than starting or stopping it from rotating. Great, thanks very much, by I was moving wise because you're Jesus Christ. It's not because of Jesus Christ. Um, I have no idea. Thanks all right. So where are you impressed with your students or none impressed? Um? I think the scores on the final tell you how impressed I should be with these students. Um. Yeah, they seem pretty perplexed, like they could not really apply the concepts of rotation and anglad momentum to this topic. Um. I like how they one of them, even God religious di went like Jesus Christ, I don't even know. Um, it's tricky. Yeah, it turns out it to be tricky. Um. But a few folks, you know, repeated what I think a lot of people imagine is the answer, which is anglar momentum. Yeah. A lot of people think, oh, it's some gyroscope effect, some conservation of angular momentum. Maybe they haven't worked through the details in their mind, but that's sort of the most common answer. Yeah, I imagine a lot of people listen to this podcast. You know, you've probably read a few science books maybe or are into signs, and you probably think you know the answer. And I imagine most people think it's has something to do with angular momentum. And so before you click off because you think you know the answer, you should know that the answer is not angular momentum. You just gave it away. Well, I just don't want it to click away. That's right, keep listening. Trust us more to it than just angular momentum. I mean, it's not even close. It's it's not like the dominating factor and why bicycles stay up right. Yeah, that's right. But let's stick into a little bit. Let's talk about what angle momentum is, how contributes to bikes staying upright, and then what else is going on? But first a quick break, what exactly is angular momentum? Yeah, so let's do it one step a time. Let's just make sure we have clear in our heads what momentum is, and then we'll extrapolate from that to angular momentum. Right. So momentum is just you know, the property of some object to keep going when you've pushed it, or to you know, not go when you haven't pushed it. It's you know, essentially it's the same as inertia, right, Like if you if you've got something going, it doesn't let's keep it going that it wants to keep going. Yeah, exactly. So we say momentum is conserved. That just means if something is moving, right, it has a certain amount of momentum. That momentum is not going to change unless you apply a force to it, right, And that's really what forces are. Forces are changes in momentum. And so momentum is just this property is something if it's moving, it like sustained movement, and it comes it's connected to inertia. It comes from the inertia. The mathematical expression for momentum is mass, which is inertia times velocity. Right, So something with more mass has more inertia and therefore more momentum for the same velocity. And that's the weird thing about the universe. Right, Like I was talking to a pretty um high level physicism. They were saying that we don't really know kind of what inertia on. Hold on, you talked to other high levels. I'm finding out about this on the podcast What Physics Cheating on You? Daniel. Well, okay, I'm putting on my two day list, find other cartoonists to talk to. Technically happened while we were while we were on a break, Daniel, So, um, it's not okay, alright, find flaunch your relationship with other physicists. Go ahead, ahead, doesn't hurt my feelings at all. Go ahead. It happened before we signed a contract together. Um, but no, no, this was this was a lamb gross. He's like the one of the head physicist at CERN, right, he is a prominent member of the Atlas collaboration and a serious Higgs physicists. Yeah, so he's thought a lot about mass. That's probably where you're going, he said. Physicists don't really know what inertia is, Like why I do things keep going the way if you don't apply a course of them. Yeah, you're right, it's an observation. Right. We call these things laws sometimes as if we like know why they happen or why the universe works this way. But a lot of times, it's just observation. We're like, well, we noticed this, and we'll be able to describe it mathematically and write it down. That doesn't mean we know why, right, It doesn't mean we couldn't imagine the universe that was different. So we don't know why things have inertia. Right. We have the Higgs boson, which tells us how things get mass, and that tells us where mass comes from. But we don't know why mass means inertia, right, We don't know how that all works, or like why if we have more mass it's harder to stop and or to get going. Yeah, exactly. Deep mystery of the universe such a basic question. We don't even know how to test it or grapple with it, right, So it's just one of those things we just sort of accept and move on, and maybe someday somebody's going to figure it out, probably by like poking some other mystery, maybe even by trying to solve the mystery of an everyday object that's around us. Yeah, like the bicycle. Yeah, that's why it's important to never let go of mysteries, right, even things that seem mundane, right, blenders and bicycles and whatever they can hide secrets to the universe. I mean, the unicycle, that's all news. But the bicycles where the frontier of sciences that that's right, all right, So that's momentum, right. People are pretty familiar with momentum. Well, there's another kind of momentum, right, Things like to keep moving forward if you've pushed them. Things also like to keep spinning, right, And that's what we call angular momentum. And this is one of my favorite tricks in physics. It's like, let's be lazy. Let's not describe something new and with a whole new concept. Let's just extrapolate from something else we already know. So we have this concept of linear momentum, and let's just use the same kind of stuff, the same ideas to describe spinning, right. And I think it was something that I would always find interesting, is that anger momentum is kind of just linear momentum. But if you apply to things that are kind of connected to each other, right, Like a wheel is really just a bunch of atoms stuck together. A wheel is a bunch of atoms stuck together. Yes, I can confirm that here on the show. I'm getting an update. Yes, yes, yes, that's true. The experiment checkt. But what I mean is like the angular momentum of a wheel is really just a linear momentum of all the particles inside of it, but because they're connected together, it sort of becomes becomes almost something else. Yeah, that's right. You have all these objects. You can think of a wheel is they're just a bunch of atoms. But if the atoms weren't connected to each other when you spun it, then it wouldn't hold together, right, And so it's the bonds between the atoms that hold them together. They think of like you know the moon going around the Earth, right, why does it move in a circle. It moves in a circle because there's a force that forces gravity that keeps it from just flying off into space. So in the case of the wheel, why do the bits of the wheels stay together and not just fly off. It's because the atoms are holding them together. So, yeah, there's forces they're moving it in a circle. But like all things, as you can, you can describe it in different levels. Right, you can describe it as a single wheel, you can describe it as eleven d billion particles. Right. The physics should work in every case. It's just sometimes the math is really hairy, and sometimes the math is really simple, and so the end result is that it behaves as if the spinning was like linear momentum. Right, you spin it, it's going to keep spinning in space for forever unless you slow it down or apply some force or torque to it. That's right. Angular momentum is also conserved, right, So if something is spinning, it's going to keep spinning until you apply the rotational version of force, which we call torque. Right. And so that's why, for example, the Moon doesn't fall into the Earth right because it has too much angular momentum. Right. That's why the solar system hasn't collapsed into a black hole because the spinning keeps it from falling in right, and so, um, there's lots of consequences of anglid momentum and the conservation of angle momentum. So it's definitely a thing. Plays a big role in the shape and the structure of our of the un verse and our everyday lives. Right. So angle momentum is definitely a thing. And it seems relevant to the bicycle because the bicycle has big spinning things on it, right, right, and angler momentum is also kind of different. Not just that it's hard to speed up, horror slow down when something is spinning in space, but it's kind of hard to change the orientation of it. Right, When when something is spinning like a wheel out in space, it's kind of hard. It likes to be It likesly not just keep spinning, but it likes to keep spinning in that direction, that's right. Angler momentum is to find along a spin access, right, And just like if you push something in a certain direction, it likes to go, not just in any direction, but in that direction. If you spin something, then it likes to keep spinning around the same access of rotation that it started. Yeah, like around the same line that goes through the hub of the wheel. Yeah, exactly. And so if you have it spinning one way and you wanted to spin the other way, right, that takes a lot of torque. Or if you have it spinning in one direction and you want it spinning around an access that's like a rotated by ninety degrees, that also takes a lot of torque. Right. So yeah, it's not just that it spins. You already likes to spin in the same direction. And so that's why people assume that's the reason bikes tape upwards, is that up boards up right right, upright right, yeah, yeah, exactly, because you imagine that this has an application of the bicycle that the wheels are spinning, and so the wheels have angular momentum, and then the momentum is around the axis or the hub around which the wheels are spinning. And so if um, if the bike just goes in the same direction, then it's going to resist falling over because it has some angular momentum around that access. And for that for the wheels to spin in another direction would require some sort of torque. And it's kind of like if you just take one wheel and you roll it down the hill or roll it down the street, it's gonna mostly stay upright, you know, kind of like a coin when you coin plus a coin or roll a coin on the table, it just kind of likes to keep rolling and stay upright. Yeah. And you can see this effect in lots of other of things in your life, like if you ever if you ever have like a spinning top, right, you know, you can spin a top and it will stay upright, and it can even like do crazy things like, you know, move you can balance it on the tip of your finger, right, um, stuff like that. You can never balance a top that wasn't spinning on your finger unless you're some sort of magician or juggler. But if it's spinning, then it's really pretty easy to keep it on your finger. And that's because it resists changing its direction because the angle momentum is going in a certain direction already. Right, It's the same thing. The same effect is in play for the bicycle. And if you are a few too too many levels into your inception dream, then the top which just keep spinning forever. Right, that's right, yeah, exactly, um. And so what happens on a bicycle While on a bicycle, for example, if your bicycle starts to fall over, right, then the gyroscope effect is essentially going to turn the wheel. It's going to turn the wheel a little bit in the direction that the bike is falling, and that will keep the bike stable. So it's not like the gyroscope of keeps the bike from leaning over. It's more that it it turns the wheel in such a way that if the bike does start to lean over, it corrects itself. Right. If you if it falls over the right. Then the forces work out just the right way so that the bike the bike um turn, the wheel turns to the right, and then the bike stays up right. Well, I mean that's what happens when you're the anglo momentum thing is what happens when you just toss one wheel down the street, right, Anglo momentum is keeping that one wheel upward. But you're saying that when I put two of them together on a bicycle, that's not the main thing that's keeping the bicycle up up right. Right, Well, I'm saying that the gyroscope effect, this anglementum does have a role in keeping the bike up right, like you said, for a single wheel, but it turns out they did some studies and it's not enough. Right there, effect is there, it's real, but it's not enough to keep a bicycle upright. And it kind of makes sense. I mean, the wheel is not very heavy on a bicycle and it doesn't go that fast, so it's not a huge amount of momentum that like if you like if you just take a bicycle and you lock the steering wheel, meaning you can't steer it, or like if you just connect two wheels with a bar and toss it down the street. It would keep going, but it wouldn't keep going upright as far as a bicycle would. R's right exactly. The front wheel has to be free to make these corrections right so that the gyroscope effect and the other effects will talk about in a minute can correct, the can can turn the wheel to correct for any leaning. That's the key to staying upright. That if you start to lean, you want to turn the wheel. Like imagine you're riding a bike and you start to fall over to the left. What are you gonna do? Well, if you turn the wheel a little bit to the left, then you're sort of going to ride into it and you'll stabilize. If you turn the wheel to the right, then you're just gonna fall over. So the key to to keep staying up righting a bicycle is that the front wheel turns in the direction that you're falling. Okay, so that's um, hold on, I think I just fell off my bike. You're mainly mental, by I hope you're wearing a helmet. That's wearing a mental helmet. Well, let's let's get let's really dig into it to sound I'm a bit confused, but we'll get into it, but first let's take a quick break. Okay, So Daniel, we know that we're trying to figure out why bicycles stay upright, and we know that angler momentum has something to do with it, but it's not, um, you're telling me, it's not the main factor wise bicycles stay upright. Yeah, that's right. And they did this really cool experiment to discover that. They said, can we build a bicycle that doesn't have angler momentum? I think that's impossible because the bike has a spinning wheel and that's definitely gonna have angle momentum. So what they did was they built a bike with two more wheels, right, and these wheels spin the other way. Okay, it's a crazy looking bicycle, but you know if you attach if you put two wheels together and one spinings clockwise and the other one's going to spin counterclockwise right because of the way they rub. And so if you just attach two more wheels that touch the original wheels, then they're going to spin the opposite way, which gives the opposite angleid momentum and the opposite gyroscope effect. So you basically have a bicycle with no gyroscope effect, no angular momentum, or like zero angular momentum, and so you would think that it would just fall over, right, because kind of like a bicycle, if you don't push it or anything and just take your hands off it, it's going to fall over because it doesn't have any angular momentum or it's not going that's right. But the universe came up with a surprise for us, right, which is why we do experiments. This is why we don't just sit in a cave somewhere like the Greeks and think about the universe. We go out and test these ideas because the universe is full of surprises. And it turns out that that bike balance is almost as well as a normal bicycle, which is like mind blowing it. For decades, people thought, oh, it's anglid momentum, it's anglimentum, until somebody finally went out there and did the experiment in checked. And you know, another experiment you can do is you can shrink the wheels. Right, if the wheels are really really small, like the size of skateboard wheels or something, or roller blade wheels, then they're gonna have much less angler momentum, and those bikes are also pretty well balanced. They stay up, they still stay up. So this sort of like blew up the cold concept. People assume for a long time that it was anglo momentum its gyroscope. I yeah, that makes sense, but nobody really tried it for a while, and so the people went out and did the experiments and turns out, Nope, that's not the answer. Where there actually like physics conferences around this topic. Yeah, somebody got a paper in science about this. I mean this is a big deal. Yeah, I mean talk about like low hanging fruit, right, I mean, it's not that hard to build this bicycle. Um, you know, you struggled in grad school for years and years. Did you get a science paper? I didn't. I had to work on a ten billion dollar collider. I still didn't get a science paper. You can make a funky bicycle, you know, with a hundred bucks and get enough information for a science paper. That's so, somebody made a bicycle with a angular momentum and it's still stay upright, Yeah, it's still could balance. You could push it by itself and it would it would have all those same behaviors. It could balance by itself. Yeah, okay, so the secret is something else about a bicycle. And you're telling me a little bit earlier that the secret is this that one of the wheels can move. The secret is definitely you have to have the front wheel being able to move. But and and there's lots of reasons why that's important, and one of them is the the angle of the forks. Right, So the forks of the thing on the whole, the front wheel in place, right connected to the handlebars, that's how you steer, and on most bikes, the angle of the forks is forwards, right, so the wheel sets a little bit in front of the handlebars. Yeah, it's it's kind of curved forward, right, It's not like a straight m fork down. It's kind of angled and it's it kind of curves up. Yeah. And I always wondered why that was. And I always thought, oh, that's just like it looks cool or I don't know, it's sort of a nice design or whatever, fancy, just like you know, like a whimsy like a little whim whimsical touch. But no, it turns out that's actually an ancient um part of the design. Like if you look back at pictures of old bicycles, even really old bicycles, have that sort of slant, and the reason is that that also helps the bike stay upright. You know, what it means is that the axis that you're steering on right this the fork the direction is in front of it hits the ground. A line along that axis hits the ground in front of where the bike is actually touching the ground. Right, the bike touches the ground the bottom of the front wheel, but the steering axis hits the ground ahead of that. And so what that means is that it's sort of following it. It's not perfectly aligned, these two things. Yeah, yeah, And so what that means is that it's one is sort of following the other. It's sort of like you know those wheels on a grocery cart and those things that are like impossible to turn around and you're gonna go backwards to painting, right. I always get the chopping card with the broken castor wheel you know that goes out. You probably are the one who breaks them, right, and you just return them this door and don't say anything right exactly. Um No, you know those wheels they do this funny thing where if you push forwards, then they follow the direction of motion right, because they're sort of behind this the steering access right, they go backwards. They always aligned in the direction where you're pushing. Yes, exactly right, which is why it's so hard to turn them around because they're aligned in some other direction. Well, it's just similar effect for the bicycle. Right. What that means is that if the bicycle starts to lean to the left, for example, then because of this angle gravity in the force from the ground is going to turn the wheel in such a way that the wheel turns in the direction that you're falling, which again helps the bike right itself. And so because this angle access is tilted, then you get that same effect. Okay, so way you're saying, Okay, I'm riding my bicycle. Okay, I'm going down this hidewalk, and suddenly I start to lean a little bit to the left, so I'm following falling falling, and you're saying, there's a because of this access cast effect, and my wheel automatically, without me having to steer, it is going to turn to the left, turn to the left. Yeah, exactly. You know how if you pick up a bicycle right the front, the front, the handlebars always turn right they never stay balanced. If you pick up a bicycle, it's always like the front wheel is spinning in some crazy direction. That's because this cast effect, and also because the center of mass of the handlebars and the wheel are not quite on top of each other. And that's another effect that contributes to the wheel turning in the direction that you're falling, okay, And that that helps me stay upright, right, because if I'm leaning left, my front wheel turns left because of these effects. And then now that's actually going to help me pick myself back up. That's right, exactly. And so these are all small effects that help a bike stay upright. And the cool thing is that you can build all sorts of crazy bicycles. And they've done this is like whole bicycle research teams now, and they've built bicycles that have no angular momentum like we talked about. They also built bicycles that have no angler momentum and don't have this castor wheel effect. Right, they angle the fork in the other direction, and I've seen this video. They can still get the bicycle to balance by itself even without the castor wheel and without angular momentum, meaning you you point to step the fork down like perfectly down, that's still works, or even backwards right the negative effect. You can even have the fork sort of pointing in the wrong direction and a bike will still balance. So bike with no angle momentum and the negative caster effect will still keep itself upright. But how does it stay upright if we if you cancel out this self steering effect? Nobody knows that I am serious. Like, turns out these equations are complicated, right, Like figuring out how a bike balances is not a simple like, oh, do to do it's angle momentum. We're done. These are complicated effects because there's lots of forces involved, lots of ways that can pivot, and so it's still a mystery. You know, Um, there's there. It definitely is influenced by angle momentum. It's definitely influenced by this caster effect. It's definitely influenced by this other thing with the center of mass about where the balance point is on a bicycle. But the truth is that it's still a bit of a mystery. Wait, so you're telling me every time I ride a bicycle, I am writing on a mystery of the universe that physicists don't know how it works. You're basically riding a black hole around town. That's what I mean. Oh my god, does does that make riding your bicycle seem more fun and exciting? It's it seems a little more dangerous, to be honest. It's not like the physics is gonna stop working. Like a whole lot of second we figured out your bike shouldn't balance and then boom, everybody falls over simultaneous sleep. That would be awesome. It's still a mystery. There are lots of effects there we don't understand. It's complicated. You know, lots of things about how people turn. You know, you lean to the right and then turn to the left, counter steering. All sorts of stuff is going on. It's pretty it's really pretty tricky, but it's important. You know, if you figure out how bicycle is balance, you could develop a new bicycle. Right, you could have some breakthrough in bicycle science. To be just around the corner, you could you could win the no No No bill bicycle right, yeah, or you know, you could make a zillion dollars whichever you prefer. But it could be that somebody comes up with a better way to make a bicycle and that sweeps the world right, all of a sudden, the way we've been riding bikes for a hundred years is like old fashioned and clunky and hilarious. Um. There's a guy in my neighborhood actually who rides a unicycle, which I think is really impressive. You mean to go place and not not just in the circus. Oh no, yeah, he commutes to work on his unicycle. Does put two of those together to make a bicycle. Maybe the bicycle just broken half? Um, but he's got one for you know, nice weather. He's got like a mountain bike unicycle. I've even seen him like on trails, trails I like struggle to walk up he's like unicycling up way Like wow, does he put does he put nails? And no, he's just got knob tires on it. I think that's more a testament that's not so much physics. That's just the brain. Like it's incredible what the brain can maneuver and accomplish if you put your mind to it. And so even though physicists haven't figured out what the equations that control bicycle are, your brain has right, your brain has an intuitive grasp of how a bicycle works and how to manipulate it, right, Well, not just me like little kids, you know, I'm talking specifically about Jorge's brain. His brain is amazing. It's amazing that I can do what a three year old can do. Yeah, exactly, But you're right, three year olds are excellent at this, right. But that's what three year olds do. They're like mapping their control of the world. Right, they're interacting with the world and getting all these feedback and figuring out how to control it. And if and kids. You know, for a long time, I've had a hard time learning to ride a bike. But if you start by just teaching them the balance these push bikes, then they're great at it. Right. It doesn't take them very long to learn to balance. Wow, well that's pretty cool. So the next time you ride your bicycle and just think about it, you are writing a black hole that's right in our knowledge of the universe. Yeah, and you know, there's some interesting physics going on there. We know a little bit about it. There's some of these effects that are happening to keep your bike up right, but there's definitely something else going on in there that we don't understand, and it could be something mundane. It could be like, Oh, it turns out these forces happened this way and there's a torque or whatever. But it could there's always the possibility when you don't understand something, that there could be a deep secret of the universe revealed. Right. That's why phyes this tugget every thread we don't understand, hoping that one of those threads is going to unravel the fabric of the universe and teach us something deep about the way when the world works. Yeah, or at least you'll get to work. Yeah, with a little bit of exercise exactly, and you'll look really cool and you'll be fit from all that biking. Yeah, that's right. Just remember to wear a helmet. That's when you do physics. And so that's why we think the physics of everyday objects is fascinating. So if there's something in your world that you don't understand, something you'd like to understand your why does this happen? Why does it work this way? How come it doesn't work this other way? Send us a suggestion. Why are shopping carts always broken? That's right? Why? And no matter where I go, did Jorhey break the wheels in my shopping cart? Has he been to every grocery store in the universe. Um yeah, anything that seems magical and your everyday life let us know. We'll try to kill the magic. See you next time. If you still have a question after listening to all these explanations, please drop us a line. We'd love to hear from you. You can find us at Facebook, Twitter, and Instagram at Daniel and Jorge That's one word, or email us at Feedback at Daniel and Jorge dot com. Thanks for listening and remember that Daniel and Jorge Explain the Universe is a production of I Heart Radio. From more podcast from my Heart Radio. Visit the I Heart Radio, Apple podcasts, or wherever you listen to your favorite shows.