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鲜为人知的自行车奥秘

Most People Don't Know How Bikes Work

Most people don’t know how bicycles actually work.
多数人并不了解自行车的实际工作原理
“Let’s try it again.”
“再试试看”
So we modified this bike to prove it.
于是我们改造了这辆车进行验证
This video is sponsored by KiwiCo.
本视频由KiwiCo赞助
More about them at the end of the show.
更多信息请看节目最后
“When you’re riding a bike and you want to turn left,
“当你骑着自行车想要左转时
I think most people just imagine
我想多数人会认为
you turn the handlebars to the left.
只要将车把向左转即可
This is a bike to test whether that is true.
我用这辆车测试下这想法对不对
And it’s made by my friend Rick here.
这是我朋友Rick改造的
And he’s got a radio controller that allows him
他有一个无线电遥控器
to lock out the steering to one side.
能把车的转向锁定在一个方向
So, what he’s gonna do is as I’m biking,
那接下来他要做的就是
he’s gonna pick whether I can turn either to the left or to the right.
决定我骑车时 能否左转或右转
So, go for it.”
那我们开始吧”
“I’m giving it a left turn.
“我先设置左转
It pulls the pin out,
插销被拉了出来
but you can see that you can still fully steer after I’ve pulled the pin out.”
你看我拉出插销后 你仍然可以转向”
– I’ve armed it. There’s where it locks. – OK.
– 装好插销 转向就锁住了 – 明白
“Now, that’s when your LED comes on
“现在 哪边的LED灯亮起
and that just says turn that way.”
就说明转向哪边”
– Turn left. – Yeah.
– 左转 – 没错
“And if I try to turn right.”
“如果我想右转”
– You can’t. – I can’t.
– 你转不了 – 不行
“And if I try to turn left.”
“如果我尝试左转”
– You can. – I can.
– 你可以左转 – 我可以
“So the question is can I
“那么 问题在于我能否
successfully execute this left-hand turn?”
成功实现这次左转呢?”
– Should we give it a shot? – I mean,
– 要不咱们试试看? – 就是说
he’s not gonna tell me whether it’s left or right,
他不会告诉我左转还是右转
so I have to look at the LED to know which way I can still turn.
我得看LED灯判断还能朝哪边转弯
– You let me know when you’re ready. – Okay.
– 准备好了告诉我 – 好了
[exclaims] No!
[惊呼]别倒啊!
“That was meant to be a turn to the right,
“本来是要向右转的
but there was no chance in hell.”
但压根儿不可能”
“Left.”[exclaims]
“左转”[惊呼]
– Right. – All right. [exclaims]
– 右转 – 好吧 [惊呼]
“Right, right, right! God!”
“右转 右转 右转!天啊!”
If you look closely, you can see the problem.
如果你仔细观察 就会发现问题所在
Here, I’m trying to turn right
此时 我正要右转
but steering that way puts me off balance.
但这样转让我失去平衡
If you could ride this bicycle,
如果你骑上这辆车
you would find it’s impossible to turn left without first steering right,
就会发现 不先向右转 是不可能实现左转的
and it’s impossible to turn right without first steering left.
当然 不先向左转 也是不能实现右转的
This seems wrong.
这似乎是个谬论
I think most people believe you turn a bike
我想多数人会认为自行车转向
simply by pointing the handlebars
只需将车把朝着
in the direction you want to go.
你想要前进的方向就行
After all, this is how you drive a car.
毕竟 你也是这样开汽车的
Point the front wheels any direction you like
将前轮朝着你想要前进的方向
and the car just goes that way.
汽车就会往那个方向行驶
But the difference with a bicycle is
不过自行车的不同之处在于
steering doesn’t just affect the direction you’re headed,
转向不仅影响你前进的方向
it also affects your balance.
还影响平衡性
Imagine you want to make a right turn,
想象一下 你想右转
so you steer the handlebars to the right.
所以你将车把转向右边
What you’ve done is effectively steered the bike out from under you.
这么做 实际上等于让车失衡
So now you’re leaning to the left,
此时你正向左倾斜
and the ground puts a force on the bike to the left
而地面给自行车施加向左的力
so the only way not to fall
所以避免摔倒的唯一方法
is to steer the bike to the left.
就是将自行车转向左边
You have made a left turn.
你就实现了左转
If you really wanted to turn right,
相反 如果你要向右转
you first have to counter-steer to the left
你得先反向控制自行车向左转
so you can lean right into the turn.
这样就能向右倾斜实现右转
This is something anyone who rides a bike knows intuitively
这一点任何骑车的人都自然而然知道
but not explicitly.
但又不明就里
“Turn left!”
“向左转!”
Film someone riding a bike towards you
拍摄面向你骑车的人
and tell them which direction to turn
并告诉他们朝哪边转
and you will find that they counter-steer
你会发现他们不加思索地
without even thinking about it.
先朝反方向转把手
“Hard left!”
“向左急转弯!”
“When you’re riding a bike,
“你骑车时
it’s exactly the same as what we call an inverted pendulum
道理就和我们所说的倒立摆
or balancing a broomstick on your hand.
或平衡手中扫帚是完全一样的
If I’m balancing it and I just start walking toward you,
如果我平衡扫帚时 只是直接走向你
it will always fall away from you.
扫帚就会倒下来
If I want to walk towards you, it’s easy enough to do
如果我想走向你 其实很容易
and people inherently know how to do it.
大家都知道
If I pull it backward, I can now start walking that way.
先把它往后拉 就能开始向前走了
I have to initiate the lean to turn into it.”
我必须先倾斜 才能移动”
If you want to move the pendulum somewhere,
如果你想向某个方向移动扫帚
you first move the base in the opposite direction.
就要先反向移动其底部
And now the pendulum is leaning in the direction you want to go,
现在长柄扫帚正倒向 你要去的方向
so you can move with it.
那么你就能和它一起移动了
And it’s the same with a unicycle.
而独轮车也是这个原理
In order to go forward, first, you have to pedal back.
要想向前骑 首先你得往后踩踏板
So, you’re leaning forward
这样 你就在向前倾了
and then you can go forward with it.
然后你就可以骑着独轮车前进了
“Everything you’re doing on a unicycle
“你所做的一切
is all about keeping that contact patch
都是为了把车轮与地面的接触点
right where it needs to be relative to you.
保持在相对于你来说 正确的位置上
You’re balancing the broomstick. It’s just that on a unicycle,
就像保持扫帚平衡 骑独轮车时也是一样的道理
you do the longitudinal balance with the pedals
你踩踏板保持纵向平衡
and you do the lateral balance, the side-to-side,
同时保持左右横向平衡
the same as you do with a bike.
与骑自行车同理
You essentially sorta small counter-steer to get that weight,
主要是稍往反方向移动 施加重力
to get the contact patch out,
使接触点移动过去
and then you can pedal and bring it under you.”
再通过踩踏板把它调整到正确位置”
Now I should point out that
现在 我要说的是
sometimes when the steering locked,
车的转向锁定时
we just happened to be leaning in the right direction
有时我们只是恰好往正确方向倾斜了
to execute the turn.
从而实现了转向
“Right, right, right, right, right, right.”
“右转 右转 右转 右转 右转 右转”
[Off Screen]”Oh, managed it!”
[画外音]“噢 成功了!”
Essentially by sheer luck,
我们基本纯靠运气
we had counter-steered before that side of the handlebars locked out.
趁着车把锁上之前 反方向转了一下
“Now, I can…I can keep going.”
“现在 我可以……一直骑下去了”
– Yeah, but don’t turn left or you’re gonna be screwed. – Don’t turn left.
– 对 但别左转 不然你就完蛋了 – 别左转
I can’t turn left.
我不能左转
“What’s interesting about this is it shows
“有意思的是 这说明
that you can still ride the bike perfectly well, right?
我还是可以骑得很好的 对吧?
It’s just you can’t turn left.”
只是你不能左转而已”
– The funny thing is that you couldn’t initiate the turn. – Right.
– 自己不能拐弯儿 太可笑了 – 是啊
“I mean, the wild takeaway is that
“我们得出了一个很棒的结论:
steering is not just for turning the bike;
转向不只是为了让自行车转弯
steering is for balancing.”
还是为了保持平衡”
“That’s exactly right.”
“完全正解”
Why is it hard to balance on a stationary bike?
为什么很难让静止的自行车保持平衡呢?
I think most people believe
我想多数人认为
it’s because the wheels aren’t spinning
是因为车轮不转
so there’s no gyroscopic effect,
所以就不会产生陀螺效应
but that’s not it.
但事实并非如此
The truth is you use steering
事实是你得通过转向
to keep the bike underneath you
让自行车保持在身体正下方
but steering doesn’t work when you’re stationary.
但当你不动时 转向是不起作用的
Your balance comes not so much
你的平衡并不取决于
from how you position your body over the bike,
你在自行车上的位置
but by how you steer the bike to keep it underneath you.
而取决于如何控制自行车处在身体正下方
Even when going straight,
即便直行时
you’re constantly making small steering adjustments to maintain balance.
你也要不断微调转向 来保持平衡
“You’re moving the contact patch of the front wheel under you.
“其实你在移动位于你下方的 前轮接触点
You’re doing exactly what you do when you balance a broomstick on your hand.”
就像平衡手上扫帚时所做的一样”
So, if the rider is responsible for steering the bike to keep it balanced,
那么 如果骑手负责让自行车转向 从而保持平衡
how do bikes without riders stay upright?
那么没人骑的自行车 又如何保持直立呢?
As long as a bike is moving with sufficient speed,
自行车只要以足够快的速度移动
it can keep coasting indefinitely.
就能不断滑行
I first became aware of this phenomenon
我最初是通过《一分钟物理》
through the great videos by MinutePhysics,
一些精彩的视频知道这一现象的
which inspired me to make this video.
是它们启发我制作了这个视频
You should definitely check them out.
你们一定要去看看
But it turned out the ground
而事实证明 虽然我们测试时
where we went to test this effect was really bumpy,
行经的路面非常颠簸
but the bike still manages to absorb all these perturbations
但自行车仍能应对自如
and remain stable.
并且保持稳定
So, how does it do this?
这又是如何实现的呢?
I think most people believe it’s the wheels spinning
我想多数人会认为是车轮转动
that creates some sort of gyroscopic effect that resists falling over.
产生了某种陀螺效应 从而避免了摔倒
Just like in this demonstration of gyroscopic precession.
就像在这里演示的陀螺进动一样
The wheel stays upright even though gravity is pulling it down
尽管重力将车轮往下拉 车轮还是能保持直立状态
But this is not why bikes are stable.
不过这并非自行车能保持稳定的原因
Just watch what happens when we lock the handlebars completely.
看看我们将车把完全锁住时 会发生什么
So you can only go straight ahead.
看来你只能向前直行
“Locked out, locked out. Whoa!”
“锁住了 锁住了 呜喔!”
“All that is happening is the steering is locked.
“现在的情况是 转向锁住了
You just got to ride it. You don’t have to turn.”
你得骑下去 不要转弯”
– You just ride. – Go straight.

– 你骑就行 – 直行
“Letting go.” Some people tried going really fast.
“尽管骑吧” 有些人试图骑得很快
[group laughs]
[人群大笑]
“Holy crap! This is impossible.”
妈呀!没戏的
Others experimented with extreme balancing techniques.
其他人则尝试用极好的平衡技巧来骑
– He’s leaning. Leaning hard. – Don’t go too fast.
– 他斜了 斜得很厉害 – 别骑太快
[group laughs]
[人群大笑]
But even with the gyroscopic effect of the wheels,
不过 尽管有车轮的陀螺效应
no one was able to keep the bike upright for more than a few seconds.
也没人能让自行车直立超过几秒钟
[crowd exclaims]”Wow!”
[人群欢呼]“哇哦!”
“This is not safe for a second.”
“太要命了这车”
It is just as hard to balance on a bike with locked steering
在锁定转向的自行车上保持平衡
as it is to balance on a stationary bike.
和在静止车上一样困难
“No, this one is impossible.”
“不可能不倒呀”
Because you can’t steer the bike back under you.
因为你无法控制自行车回到身体正下方
The real reason bicycles are stable without riders
没人骑的自行车能保持稳定的真正原因
is because they’re cleverly designed to steer themselves.
是因为它们能自动转向的巧妙设计
If they start falling to one side,
如果它们开始倒向一边
the handlebars turn in that direction
车把就会朝那个方向转
to steer the wheels back underneath them.
来控制车轮回到车把正下方
At least three mechanisms are responsible for a bike’s corrective steering.
至少有三种机制 与自行车自动纠正转向有关
The first is that due to the angle of the front fork,
首先 由于前叉的角度
the steering axis intersects the ground
转向轴在车轮与地面接触点的前方
in front of where the wheel touches the ground.
与地面相交
So, if the bike starts leaning to the left,
所以 如果自行车开始向左倾斜
the force from the ground on the tire turns the wheel to the left.
地面对轮胎的作用力 就会使车轮转向左边
If the bike starts leaning right,
如果自行车开始向右倾斜
the force from the ground pushes the wheel to the right.
来自地面的力就会把车轮推向右边
The front wheel of a bicycle is essentially a caster wheel,
本质上 自行车的前轮就是个脚轮
like those you find on strollers or shopping carts.
就像我们婴儿车或购物车上的脚轮
Whichever way you drive them,
无论你朝哪个方向推车
the wheel falls in line and rolls in the same direction.
轮子都会成直线 并朝同一方向滚动
The second reason for a bike’s corrective steering is that
自行车能自动纠正转向的第二个原因是
the center of mass of the handlebars and front wheel
车把和前轮的质心
are located slightly in front of the steering axis.
略位于转向轴的前方
So, when the bike leans left,
所以 自行车向左倾斜时
their weight pushes the front wheel to the left.
其重量会把前轮推到左边
If the bike leans right, their weight steers to the right.
如果自行车向右倾斜 其重量就使车右转
And the third mechanism is a gyroscopic effect,
第三种机制确实是陀螺效应
but it doesn’t keep the bike upright directly; it just helps steer.
但它不能直接让自行车直立 只能辅助转向
If you have a gyroscope and you push down on the left-hand side,
如果你有个陀螺 把左手边向下推
the gyro will turn left.
陀螺就会左转
If you push down on the right side, it will turn right.
如果把右边向下推 陀螺就会右转
This is known as gyroscopic precession.
这就是所谓的陀螺进动
It seems as though the force you apply
我们施加的力
takes effect 90 degrees from where you applied it.
似乎在施力点90度处起了作用
So, bikes are stable primarily because of steering.
所以 自行车稳定主要是靠转向
They have built-in mechanisms for steering themselves.
它们有内置的机制来实现自动转向
In fact, you don’t need all three mechanisms to create a stable bike.
事实上 无需兼具三种机制 才能保证其稳定
Researchers created this weird-looking bicycle to prove a point.
研究人员发明了这辆外形怪异的自行车 来证明这一观点
It has no gyroscopic effect
由于接触地面的轮子上方
thanks to counter-rotating wheels above the wheels that touch the floor.
有反向旋转的轮子 所以这辆车没有陀螺效应
Plus, there is no caster effect
而且 因为前轮在转向轴前方
because the front wheel touches the floor in front of the steering axis.
先接触地面 所以也不存在脚轮效应
But this bike is made stable by its mass distribution,
其实 这辆车是靠其质量分布来保持稳定的
the force of gravity on which steers it in the direction of any lean.
重力使它转向任意倾斜的方向
Understanding how bicycles work is still an active area of research.
理解自行车的工作原理 仍是个活跃的研究领域
There is a program you can use to input all the different bicycle parameters
这里有个程序 你可以输入所有不同的自行车参数
and see the range of speeds over which it is self-stable.
并查看保持自行车自身稳定的速度范围
And this research is leading to better bikes.
这项研究将创造出更好的自行车
This prototype has a smart motor in the handlebars
这款原型车的车把上有个智能马达
to actively help steer, keeping the bike upright even at low speeds.
可以辅助转向 即使自行车低速行驶时也能使其保持直立
I guess it’s fitting that we are still learning new things about bicycles
我觉得 大家仍在学习自行车相关的新知识非常不错
since most of us are able to ride one
因为我们大多数人都会骑车
without any knowledge of how we’re actually doing it.
却不了解实际原理
[futuristic sound effects play]
[科幻音效]
Hey, this video is sponsored by KiwiCo,
嘿 本视频由KiwiCo赞助
creator of awesome hands-on projects and toys
它创造了很棒的实践研究项目和玩具
designed to expose kids to STEAM concepts.
旨在让孩子们接触STEAM概念
And with the holidays fast approaching,
随着假期临近
a KiwiCo subscription is the perfect gift
对你身边任何一个年轻人而言
for any of the young people in your life.
订购KiwiCo都是一份完美的礼物
KiwiCo now has nine different subscription lines
现在KiwiCo针对不同年龄层和主题
for different age groups and topics.
有九种不同的订购渠道
Plus, they ship to more than 40 countries.
而且 产品销往40多个国家
I think it’s such a great gift
我觉得这真是份很棒的礼物
because each month a box turns up at your door
因为每个月都有个盒子出现在你家门口
and provides hours of entertainment and learning.
供你娱乐和学习几小时
My kids love building KiwiCo projects with me.
我娃很喜欢和我一起搭建KiwiCo项目
It’s a special thing we do together
我们一起动手制作 这很特别
and you can jump right in
你可以马上加入进来
because each box comes with all the supplies you need,
因为每个盒子里都有你需要的全部东西
even a few extra in case you lose something.
甚至还有一些备份 以防你弄丢东西
You know, today I built this waterwheel fountain
今天我搭了这个水车喷泉
in fitting with the wheel theme.
来搭配车轮主题
The design and instructions are so well thought out
设计和说明书都是如此的精细周到
because each project is designed by experts
因为每个项目都是由专家设计的
and tested with kids.
并在孩子中测试过
There’s also an educational magazine
还有一本教育杂志
with lots of additional content around the crate’s theme.
里面有许多与盒中主题相关的附加内容
For viewers of this channel,
对于本栏目的观众
KiwiCo are offering 50% off your first month of any crate.
KiwiCo将会给您首月订购打五折
Just go to kiwico.com/veritasium50.
只要进入kiwico.com/veritasium50即可下单
I will put that link down in the description.
我会把链接放在产品描述里
So, I want to thank KiwiCo for supporting Veritasium
我想感谢KiwiCo对《真理元素》栏目的支持
and I want to thank you for watching.
也感谢您的收看

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视频概述

本视频介绍了自行车能够平稳行驶的工作原理,并通过具体试验进行说明

听录译者

收集自网络

翻译译者

Carolyn

审核员

审核员TL

视频来源

https://www.youtube.com/watch?v=9cNmUNHSBac

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