Hacker News new | past | comments | ask | show | jobs | submit login
Uncontrollability of a bricycle (2014) [video] (youtube.com)
539 points by gballan 11 months ago | hide | past | web | favorite | 228 comments



This reminds me of the backwards brain bicycle a bit [1]. I get that the argument they’re making here is one of physics - but failing to ride a counterintuitive bike isn’t something that can just be ‘done’ without a lot of practice!

[1] https://youtu.be/MFzDaBzBlL0


A long time ago I saw a documentary where a guy wore special glasses that turned everything upside down. He wore them all day except when sleeping, and masked his eyes when sleeping. After a couple weeks, suddenly the world was right side up again.

But taking the headset off, now everything was upside down.


https://en.wikipedia.org/wiki/George_M._Stratton

Interesting dude. Experiments seem to have been about a century ago.

(I thought I'd read that this had been done earlier, but Stratton comes up when looking for "glasses that turned everything upside down" as mentioned)


I have been trying to ride the other way on my fixie[0] lately. I think this is kinda the same. I know what I have to do, but instinctively it all gets wrong. I can kinda override it, but then my reactions are way too delayed. So here's hoping for it will click some day..

[0]: A fixie is a bike with no freewheel. So the pedals follow the back wheel, and the other way. So if I pedal backwards, the bike goes the other way.


The sport trick cycling has this in a lot of tricks. You might find some advice there if you want.


A quick search yielded this as the top result [1], incredible! I'm going to blame you for breaking my neck when I attempt this later, haha.

[1]: https://www.youtube.com/watch?v=kUiiJI_tPVk


I used to do that as a kid (stopped before I could do all the tricks in the video). You want to have a suitable underground(1) and a friend to catch you the first few tries until you know where the bike goes when you fall. The main path to injury is falling onto the bike. If you avoid that it's way safer than football/soccer. Note that the bikes in the video have a different center of mass from normal bikes so it's easier to get the front up. Have fun!

(1) In Germany we do this in clubs and proper sports halls as seen in the video with elastic flooring. Don't attempt tarmac until you definitely know what you're doing.


I also recommend learning to ride a unicycle for people who want to get better bike skills. It's like riding a bike except with a brand new plane of movement.

It's also very safe to try out and do, which is counterintuitive to most people who haven't tried. Overwhelmingly the most common failure mode on a unicycle is that you just stop riding it, and then it either gets ahead of you or behind you, and you hop onto the ground.

Your body's also always approximately vertical no matter what they incline you're riding up/down is. So e.g. riding down stairs on a unicycle is much safer than on a bike, if you screw it up you just let it roll ahead of you and you're standing on the steps.

I'll do that without hesitation on a unicycle, but on a bicycle there's no way I'm doing that on on anything except a mountain bike I trust.


>It's also very safe to try out and do, which is counterintuitive to most people who haven't tried. Overwhelmingly the most common failure mode on a unicycle is that you just stop riding it, and then it either gets ahead of you or behind you, and you hop onto the ground.

Ha. My experience with a unicycle was the exact same as my experience with Segway and Hoverboard: flat on my back, knocked-out cold, with back-sprain that lasted months.


The biggest safety feature of a unicycle is that you don't even try to go fast.


At first you don't.

But then there are 36 inch unicycles, which can go quite fast. I started with a 24' (< 10 km/h), then I bought a 29' (< 18 km/h). The 29' does feel fast. One day, I'd like to buy a 36', which would be a bit slower than a bicycle, but still quite fast. Some people ride them around the world [42].

[42] https://www.youtube.com/watch?v=5WrGJ8A0Y1o


Worth pointing out that while learning, failed mounts can result in the unicycle departing the vicinity at some speed (especially with smaller ones, e.g. 20").


If you like this, take a look at Radball (cycle ball): https://www.youtube.com/watch?v=0moQPqtmrTY

Maybe not as elegant as the artistic cyclists, but that almost incidental level of control is insane.


Driving backwards is much more difficult than driving forward because the bike doesn't self correct that way and the steering is quite unstable.

I tried to learn riding backwards last summer, too. Eventually I stopped because I needed the bike for actual riding and my knees preferred having a freewheel. A ridiculously low gear seemed to help, I tried 40x20 (on a 622 with 165mm cranks) for a while.


huh.. I grew up on a fixie.. I wonder if 20 years later I would just pick it up again.. or 30 years later..

note to self knock up wife.. get child fixie bike.. take bike for self when kid is at school xD I'm sure the experiment will be worth the college debt.


I believe you can buy hubs that are single speed and then if you flip them are fixie, might be cheaper to put that on a cheap bike than having a kid...


Yup, they are called flip-flop hubs, quite common and a bunch of bikes come with them installed so you can always choose between singlespeed or fixed gear.


I can't ride straight backwards, but I can ride backwards in a circle from a trackstand fairly easily.


Reminds me of the time I learned Dvorak.


The thing is, I don't actually know what the editing commands are on my editor. My fingers know them, though. Sometimes I watch my fingers to see what the command is.


I have this pretty much 100% of the time when I'm playing a piano piece, especially an older piece that I've somewhat forgotten. It's not so much that I'm re-learning the notes, it feels more like I'm coaxing the requisite movement back out of my hands. It's hard to explain, like... I can't really start a musical phrase halfway through because I don't know what notes I'm actually playing without the sheet music in front of me. But if I start at the beginning, my hands will do the right thing from muscle memory.


I use to have the same trouble with my locker combo in high school. I could spin the lock open, but I couldn't tell you the numbers.

I would occasionally lose the muscle memory too, for about a week at a time.


I hardly know what my password is.


Every time I change my work password, I commit it to memory for about a day, until it's in my muscle memory. Shortly after that, I can bang it out on a keyboard in easily under a second, but I cannot write it on a piece of paper.


Random anecdote/fact; an ex GF in HS was Dvorak's niece... she didn't have very nice things to say about him, just said he was super full of himself. I was really interested in meeting him, but after all the things she had to say about him, I lost interest, and stopped thinking I would be "cool" to switch to dvorak.


Good thing I chose colemak over dvorak ;)

Off topic: I didn’t do it for speed though, I did it for typing comfort, and as someone who has had RSI scares, I’m really happy with my decision (and with my decision to get a Kinesis Advantage ergonomic keyboard). My two main activities these days are hand-intensive: typing and sleight-of-hand card magic. I need my hands to be in good shape! Honestly, I’m a little baffled by how few programmers use ergonomic keyboards, since their hands are so important to what they do, but only a little, since it took me years before I finally bought one myself despite thinking about it for a long time (I regret not doing so sooner).


The cost of the alternative shape keyboards put me (and a lot of colleagues I've talked to) off for a long time. Glad I did finally save up to buy one! Pity I work on the road a lot and have to still use laptop keyboards a lot of the time.


The cost was definitely a big part of it, I delayed for a long time because it seemed too expensive to me. In hindsight, given how much time I spend typing, it really isn't expensive at all, its just a big up-front cost... I now even use a 3 button foot pedal and love it.

> Pity I work on the road a lot and have to still use laptop keyboards a lot of the time.

Yeah, I use laptops and an iPad too and its obviously not very comfortable in comparison. Luckily I've managed to avoid it a lot lately, but its not always possible. It really sucks when I have to use an ordinary keyboard though and I definitely feel the discomfort :/


The cost of a single PT appointment (much less a handful) should be enough for most people on dev salaries to consider the extra cost of a good ergonomic keyboard. Something something Sam Vimes and boots.


This was my exact experience in learning an alternate keyboard layout. Worked out great for RSI and I've never looked back (though it was painful to start).



Haha! That's great, thanks for posting, got a good laugh from it :) If only I had hands like that ;-)


and stopped thinking I would be "cool" to switch to dvorak

If you're thinking of switching (or not) to a product or service because of the inventor's personality, you're already "not cool".

If people based their use of Linux on Linus's personality, it'd still be a hobbyist OS.


I was going to say the same thing. And when I wen't back to QWERTY, it eventually switched and I could type fast.


It is possible to achieve high typing speed on both; I did just that for a few years by switching back and forth on a regular basis. In the end the inconvenience simply wasn’t worth it and I gave up.


Did you give up QWERTY or Dvorak?


Not the original commenter, but I had a similar experience, and gave up QWERTY. I point and peck the few times I have to use it (which isn't often, except on phones where it doesn't really matter for me) and that's worked well enough for me for many years.


Back in the day I could easily ride a bicycle without using my hands from the start with just one or two pedal stroke. I believe riding a backwards bicycle would have been easier if you dont use your hands.


That's how to win his $200 prize!


I suspect that this one is more like if you were stuck in space with no propulsion and nothing to throw... so you can't move.


Awesome link. Thank you.


His videos are amazing. I recommend Prince Rupert's Drop among many many others.

https://www.youtube.com/watch?v=xe-f4gokRBs


What you unconsciously do when turning, is to quickly turn it a bit in the other direction first in order to get the bicycle more to the other side of you, so you have a better balance point for the big turn. Not perfectly explained, sorry.

But try this: Try following a straight marker on the road on your bike. It's very hard. When you start going too much to the right, you will find it impossible to actually nudge the bike back to the left, unless you accept that you have to go further to the right first.

This also happens when driving close to a curb. It feels like it's sucking you in.


That's countersteering [1]. I find it very hard to explain but it's something that most people on a bicycle (at speed) or a motorcycle (again, at speed) do naturally.

[1] https://en.wikipedia.org/wiki/Countersteering


I'd like to especially highlight your 'at speed' point here. It's often claimed that _all_ steering on a bike requires countersteering, but that is false. Countersteering allows rapid change of direction, but if you're going in a straight line, then lean left and gently steer left (or just lean left and allowing the front wheel to steer itself), you _will_ go left, no countersteering required.


Motorcycle courses put a lot of emphasis on countersteering because motorcycles go much faster and weight a lot more than a bike so you need to familiarize yourself with the effect from the get go unlike regular bikes where you generally start by going very slowly and the low bike-to-meat weight ratio means that it's relatively easy to steer by leaning with your body as you mention. As soon as you go over, say, 20km/h it's critical to learn how to countersteer properly if you want to keep control.

Try turning on a 200kg motorcycle going at 100km/h by simply leaning on it, you'll be disappointed... See for instance https://youtu.be/8_5Z3jyO2pA?t=2m24s . Later on the video they show that letting go of the handles and leaning with your body also works but only because it actually causes the bike to countersteer "on its own".


Yep. It is even more pronounced on a race track with long sweeping turns, even higher speeds, and nothing else in the world to worry about# (like traffic). The faster that front wheel spins, the more it wants to keep on doing that just as before (gyro).

You will be physically pushing the left hand and pulling your right to set the bike up for a left turn, not just "thinking" it - so as to speak. Of course it is entirely intuitive, until perhaps you stop to think about what actions you are taking, and then realise yeah that's countersteering all right.

#) It's been a few years for me now and I only got a few ride days in after also completing Superbike Cornering School lessons, but I found the art of riding my (then) 600cc GSXR motorcycle on a high speed circuit (Phillip Island) extremely meditative - and exhilarating, especially after learning the function of the knee sliders to assist with controlling lean.


If you lean left, front wheel will "do" countersteering itself (same as noted). Since gyroscopic effect on bike is not so big and speed, mass is not bigger than rider it is not noticable. For motorbike you cannot just lean hence need for explicit countersteering because of much higher forces involved.

So I think it is correct to say that countersteering is always required.


>If you lean left, front wheel will "do" countersteering itself (same as noted).

I am not sure. If you lean left, then the handle bar ll slightly turn left automatically.

In actual countersteering, it greatly helps only because it helps to quickly initiate a tilt in the required direction. For example, if you want to go to left, then turn the handle bar to the right, which causes the front wheel to slight start to offset in the right, which in turn causes the whole bike to tilt to left, and once it start to tilt to the left, then the normal process of turning is applied...


It's always countersteering. Doesn't even matter if your hands are on the bars (really).

When you lean to (your) left, the center of mass of you+bike goes left of the plane of the wheels, this causes the front wheel to rotate away (i.e. right) from the motion slightly which causes you to bank left and the front wheel comes around to meet it until you are in equilibrium again.

Countersteering doesn't "help", it's just unavoidable. Being aware of it helps you have better control. At very low velocities the effect is so minor you probably can't notice (and steering angles are large).


> When you lean to (your) left, the center of mass of you+bike goes left of the plane of the wheels, this causes the front wheel to rotate away

This does not seem correct. Why does it cause the front wheel to rotate away (right) ?

If you lean a stationary cycle to the left, the front wheel will turn left.


  Why does it cause the front wheel to rotate away (right) ?
Answer is : "it's complicated" , which is why this subject causes confusion. There are many arguments about the exact dynamics (combinations of gyroscopic effects, torques, center-of-mass motion), but empirically it is pretty clear that two wheeled vehicles like bikes/motorcycles do not turn without counter-steer.


Not at all complicated. A bike is made so that the front wheel will turn in the same direction as the bike is leaned. This has a simple stabilising effect. Bike leans right, front wheel turns right, increased centrifugal force from the sharper turn will unlean the bike to the left.


> Bike leans right, front wheel turns right

Agree. But this is not what the other person is saying.


Except, it doesn’t at first. Which is why this is counter intuitive.


If you lean your body to the left the bike reacts by leaning to the right. Your body can only move by pushing the bike in the opposite direction.


I shouldn't have mentioned 'leaning left'.

If I'm in contact with the top of my bike and not steering the bars, I can either push the top of the bike left or right. I push the top of the bike to the left. The bike and I have separate moments of intertia around longitudinal axis. Without any other forces involved (just my bum and the top of the bike pushing each other), the bottom of the bike i.e. the contact patch would move to the right. However, there's friction between the tyres and the ground meaning that doesn't happen. Instead, the ground pushes the bottom of the wheels to the left. This means the only external force on the union of rider and bike is from the ground pointing leftwards. This pushes the COG to the left.

While the motion of the top of the bike may cause some countersteering in the front wheel if left free, you can resist this by pushing the right side of the handlebars i.e. steering left. So we now have a bike tilting to the left, with the front wheel pointing forwards, and the COG to the left of the contact patches. The front wheel can be gently pushed to point left.

No countersteering involved.


That is bullshit. If I just lean to the left, the bike does not "react" by leaning to the right. If I lean to the left without touching the handle bars, the cycle ll start turning to the left.

With counter steering, it can be made much quicker and in a much responsive fashion.


The point is that the wheel, which is free, will turn to the right first. The bike will lean to the left as this takes the two wheels out of line. The wheel will follow to the left.

There is nothing magical about countersteering, it’s just the way cornering works with bikes.

Don’t believe me? Set up an angle indicator and video it.


A bike is standing straight, completely still, with the front wheels completely straight. According to you, if I lean this stationary bike, to left, you are saying the front wheel will turn to right, right?


Counter steering is a property only while it is rolling forward. You’ll have to be moving reasonably fast to notice it easily.

In context this was clear but I should have been more explicit.


The part you are missing is the gyroscopic procession from the wheels. When you try turning the wheel to the left, you create a force that is 90 degrees to force.

If you just turn the handlebars (which would cause the bike to lean in the direction of the turn), you will end up creating a force at the top of the wheel in the opposite direction of your tilt. (e.g. the force will be at 12 o'clock)

If you just lean in the direction you'd like to turn, the wheel will turn in the opposite direction of the lean. (e.g. there will be an opposite force at 9 o'clock)

In order to turn you must always briefly steer in the opposite direction you'd like to turn, so that you may lean in the direction you'd like to turn, which will allow you to turn the wheel in the direction of the turn without upsetting the bike.

I learned this fact about 2 years ago and I've been hyper-aware of the fact ever since. Try as I might, it's literally impossible to steer a bike without counter-steering.

The fact that you absolutely must counter-steer to turn is one of the reason why inexperienced bike riders tend to fall over when they need to steer in an emergency, because they just twist the handlebars, which catapults them off the other side.

Knowing this also helped me finally learn to ride a bike with no handlebars, since you have to lean opposite the direction you'd like the wheel to go.


It's timing dependent. Turning right and momentum 'pushes' your body to the left, but with the correct timing you end up countering that force while keeping the bike absolutely vertical.

PS: Picture how a car turns, the wheels are vertical and you can you can turn without counter steering just fine but the weight externally offset. The difference with a bike / motorcycle is just how difficult it is to balance.


It is not timing it is balance of mass and conservation of energy. Car has totally different mass distribution. So energy conservation is also different.


> countersteering is always required

Only on a motorbike.


The steering geometry is exactly the same.

The only time you steer left to go left is if you're going so slowly that the only reason the bike doesn't fall over is because of your near-superhuman balance. That is to say, when you're practically at a standstill. Anywhere approaching walking pace or above, if you try to turn left by steering left, you'll fall off the right hand side before you make any appreciable turn.


> if you try to turn left by steering left

Well, if you're leaning left when steering left, I don't see how you'll fall to the right


That's the issue; how do you lean left to start with? If the human-bicycle system has its center of gravity over the wheel line, shifting your weight relative to the bike doesn't move the center of gravity - you lean one way, the bike leans the other, and you end up in the same overall position. The only way to initiate a lean to the left is to countersteer to the right.


That's weird since I don't think I'm countersteering when turning.

Or perhaps I'm doing it unconsciously?


> Or perhaps I'm doing it unconsciously?

You are. I proved this to myself once by applying pressure to the handlebars using only the palm of my hands on the backside of each handle. Even at very slow speeds, I could not for the life of me turn left by applying pressure only to the right bar (to turn the front wheel to the left). No amount of leaning helped. To lean the bike, I needed to create some external force to push it over. Leaning my own body to the left just made the bike lean to the right.


I'll have to check, because I don't believe it. I wonder who's right: me or a bunch of randos on an internet thread.


I've seen the same claim from a lot of people who seemed to have thought about it a lot: that you always countersteer on a two-wheeled vehicle, but you only do so consciously if you're riding a very fast vehicle or you want to turn extremely quickly. (A deliberate countersteer is taught in some bicycle safety classes as an "emergency quick turn".)

This is counterintuitive to me as a regular cyclist, but I realize that most of my cycling skills are completely unconscious, so I don't have a lot of confidence in my ability to describe exactly what I'm doing on my bike.


I've only ever riden a bike and very rarely at high speed (for a bike), so that explain why I never had to countersteer consciously.


That's what I used to think until I started taking motorbike lessons.

At first I was having a hard time turning, because this whole counter-steering thing didn't come naturally to me and I would try to turn the handlebars to the left if I wanted to go left, but the bike would go the other way witch was pretty scary.

I then internalised this and the next time I rode a bike I tried this out, and indeed, this is how it works. If I turned the handlebars left at any considerable speed, the bike would lean to the right and start turning right, with the handlebars going right. It would go a slight bit left at the very beginning, but then it would go all the way right.

When I think about it, at slow speeds (say below 25 km/h - 15 mph) I only turn the handlebars and lean the bike. However, I can lean the bike at those speeds, so no counter-steering is required. I first lean the bike and then turn the bars. However, it's very difficult to have it lean any useful amount at speed. And this is where counter-steering is useful.

Here's a video where this is all explained, complete with fixed handlebars (that don't steer the wheel) to show how just leaning doesn't do much : https://www.youtube.com/watch?v=8_5Z3jyO2pA&feature=youtu.be...

Granted, this is way more noticeable on a motorbike that on a bicycle. Maybe the weight of the wheels and of the whole bike has something to do with it. If I lean a 10 kg bike but stay upright on it, the centre of gravity doesn't move much. However, on a 300 kg motorcycle, it moves quite a bit more.


> If you lean left, front wheel will "do" countersteering itself

The same applies to a bicycle.


> Only on a motorbike.

Only above a certain speed, at low speeds countersteering will not work

Similarly above a certain speed on a bicycle countersteering is the only way you can turn


Some people seem to describe this difference as unconscious countersteering versus deliberate countersteering, that is, that the difference isn't really whether you're countersteering or not, but whether the countersteer is large enough that you have to do it "on purpose".


By leaning and letting the front wheel steer itself, you can turn with hands off the handlebar. When I used a bike to go to the train station, I'd often bike without touching the handlebar for parts of the ride, including the turns. Yes, I was young and stupid.


Maybe I am still young and stupid, but I cycle a lot and as often without hands on as the situation allows... It is just much more comfortable this way. Bu yes, also more dangerous, so in difficult trafic I usually don't do it


One pothole man. One pothole all it takes. I'm sure you already know but just in case, take it from me.

Picking gravel out of my arm for hours after.


Yeah "Picking gravel out of my arm for hours after." this I know as well, but the last time I fell, was 10+ years ago ...

And I even drive at night, without light on forrest roads without hands ;)

So maybe I push my luck too much, but I am also confident in my skills and reflexes ...


Yeah, I was lucky that I was doing this in an area with good roads. At least our taxes got us that.


It's true, but in all the years of my childhood when I did this (and I rode and turned no-handed often), I never once had an accident when my hands were off the handlebars. Your warning is still useful, I think, but I also think good judgment goes a long way here.


That's my experience too. If you very slowly lean to one side then you can start the turn that way.

Countersteering moves the bike to one side which means you're no longer balanced and so rapidly fall the other way initiating the turn.


I've introduced confusion here by talking about leaning left. I should have said 'shift your weight such that the bike leans left'. See my other comment for a fuller explanation.


> It's often claimed that _all_ steering on a bike requires countersteering, but that is false.

Sounds like you've never ridden a motorcycle? It's obvious on a motorcycle that you counter-steer all the way through a turn.

If you analyze bike steering more carefully, you will also find that you're always counter-steering. But the definition of counter-steering might be different than you think.

You have to think about the front wheel's turn angle in relation to your turning radius. If you're riding in a right turn circle, then your wheel position will be turned right and not changing. In order to change that turning radius, you will always steer in the opposite direction of your desired direction relative to where your steering is at steady state.

So counter steering doesn't mean that if you are turning right your wheel is left of center. Counter steering means that to turn more right, you need to steer left of where you were. When making small adjustments, your steer might be right of center at all times even though you go from a right turn to a sharper right turn.

In other words, it's the delta of your steering angle that is always counter, not the position of your steering angle.

Does that make sense?

One easy way to understand why you're always counter-steering was given in the video: a bike is physically equivalent to an inverted pendulum. In order to move the pendulum in a given direction, you always have to move the base the other way, at all times. This is true on a bike too.


> Sounds like you've never ridden a motorcycle? It's obvious on a motorcycle that you counter-steer all the way through a turn.

Once the turn has been initiated and you are in the turn, I don't believe you continue to counter-steer.

I think instead that once in a turn you feel a force trying to continue the front wheel deeper into the turn and you must maintain a counter force to prevent that. It seems unlikely that the front wheel is actually angled out away from the turn.


> Once the turn has been initiated and you are in the turn, I don't believe you continue to counter-steer.

Sounds like you haven't ridden a motorcycle? In a hard right turn, you will need to keep constant pushing pressure on the right handle (steering left) in order to stay in the turn.

And maybe you didn't follow the rest of my comment? Counter-steering doesn't mean your wheel is left of center during a right turn. It's referring to a change in turning radius. At all times. Yes, your wheel might be turned right during the stable lean angle of a right turn (or it might not) but "counter steering" is referring to when you change your turning radius. You always steer the opposite direction that you were steering before. If you're in a right turn and want to turn sharper, you steer the wheel left of wherever it is. If you're in a right turn and want to straighten out, you steer the wheel right of wherever it is. It doesn't matter where the wheel is, all that matters is which direction the change happens.

If you're in a stable lean with a constant turning radius, then your steering isn't changing, so I guess perhaps technically you're not counter-steering, because you're not steering? This is more confusing than clarifying, and not always true anyway. It's better to realize that the "counter" in counter steering is referring to the derivative, not the absolute value. It's referring to the change in steering, not the angle the wheel is turned.

> It seems unlikely that the front wheel is actually angled out away from the turn.

You might want to google gp moto pictures before making claims, you can find tons of images of racers in the middle of the turn with the wheel angled outward. For example: https://i.ytimg.com/vi/dtCD63fKw58/maxresdefault.jpg


> Sounds like you haven't ridden a motorcycle?

Repeating this is so unnecessarily condescending.

> In a hard right turn, you will need to keep constant pushing pressure on the right handle (steering left) in order to stay in the turn.

This is not usually true (though sometimes is at slower speeds.) Bike geometry and speed changes how this works a good bit [1][2]. Tracking my old 600cc, I'd need positive at slower speeds, but would need to steer into the turn once I had a good lean angle at anything 60mph+.

> You might want to google gp moto pictures before making claims, you can find tons of images of racers in the middle of the turn with the wheel angled outward. For example: https://i.ytimg.com/vi/dtCD63fKw58/maxresdefault.jpg

This is really uneccessarily condescending again. Also, that really looks a rider deepening lean as he rounds the apex. I'm thinking that wheel's not staying at that angle for long.

I encourage you to check the tone of your comments. Being rude to folks, especially while being wrong while doing it really brings down a community, and I hate seeing that happen on HN.

[1] https://en.wikipedia.or/wiki/Countersteering#Stable_lean [2] https://www.cycleworld.com/2013/10/25/know-how-to-counterste...


> Repeating this is so unnecessarily condescending.

I didn't mean it to be condescending, it's an honest question. People commenting don't seem to have the experience to back up their comments. I know for a fact that a hard turn on a motorcycle sometimes requires obvious counter-steering even during the stable middle of a turn, because I've done a lot of riding. I agree that bike geometry and speed changes things, but you've just validated what I said with your experience.

> I'm thinking that wheel's not staying at that angle for long.

Your assumption is incorrect, you can see it more clearly if you watch videos. The extreme counter-steer during moto races happens all the way through a turn, and then it happens in the other direction in order to end the turn. The part you and the parent comment missed is the bike forces try to un-lean when moving forward, and it becomes very apparent at higher speeds, so constant counter-steering is necessary.

> I encourage you to check the tone of your comments. Being rude to folks, especially while being wrong

I know it can be very hard to understand someone's tone, but it's equally wise to check your assumptions and your own tone. I was simply trying to make my point clear precisely because it appeared the comment above didn't understand what I said the first time.

You've claimed I'm wrong, but I don't believe I am, and I've provided evidence for my case. From my point of view, pushing back on that without evidence is rude, as is arguing against my first sentence apparently without reading the rest of the clarifying explanation.

BTW, what you didn't see is that I upvoted @JKCalhoun for engaging in the discussion.


re: condescending repetition

It really is a form of not-at-all-subtle trolling. If you feel like you're talking to a wall on the internet, the correct move is to stop interacting with a waste of time.

Or don't repeat yourself, because the text is static, and it's not required. You put it there once, and it's still there. Forum sliding with spammy garbage doesn't make friends. Saying the same thing a different way still amounts to an internet fight, but it's arguing without trolling.


Since you are new here, you should know that the HN guidelines recommend assuming good faith at all times. They also suggest avoiding flame bait, which is what accusing someone of trolling is. https://news.ycombinator.com/newsguidelines.html

You've mis-read my motives and this situation, perhaps @jaxwerk's suggestion that I was being condescending was enough to convince you it was true, however that comment is making an incorrect assumption. I didn't feel like I was talking to a wall, I asked the same question of a different person, a person who after I asked the first time, suggested that motorcycles tend to lean into a turn when turning. If you've ridden a motorcycle and know how to counter-steer, you'd know that motorcycles tend to right themselves while turning and that you have to keep counter-steering in order to maintain the turn.

My question was honest. I know from experience that the question of whether someone has ridden a motorcycle is very important when discussing counter-steering. Many people who've only ridden bicycles don't believe counter-steering exists at first. The people who understand counter-steering are the people who've taken a motorcycle safety course and/or learned about motorcycle racing and/or experimented while riding. It's much, much easier to feel & understand counter-steering on a motorcycle than a bike, and it's far, far more important.


I've never ridden a motorcycle, you are right.

>Does that make sense?

No, but English is not first language, I'm lacking some technical vocabulary.


Well, my description isn't amazing or as clear as it could be. ;) There should be a way to explain this without technical vocabulary.

How about this? If you sit still on a moving bike, and you don't try to lean, bike steering changes your lean. While you are turning your wheel further to the left, your lean to the right is increasing (your right side turning radius is decreasing).

That's it. That works for negative angles and negative lean, meaning if you're steering right and leaning right, then you start moving your wheel to the right, your left lean increases because your right lean decreases.

And it's always true. No matter where you start, you could be already turning left or right, steering more to the left always sharpens your turn to the right.

Does that make any more sense? I really do want to find a better way to describe counter steering so it becomes more intuitive and easier to understand.


Yes, that explanation made much more sense, thank you for taking the time to write it. I'll have to check for that next time I'm on a bike.


Counter steer happens at all speeds at all times on a two-wheel vehicle, it's just hard to notice at slow speeds, and confusing because you do steer right during the stable lean angle portion of a right turn, as depicted in the first image in that Wikipedia article.

I think counter-steering is misunderstood since people assume it means that if you're turning right then your steering has to be left of center. But counter-steering is referring to the direction of change, the steering delta, not the absolute steering angle. You always steer in the opposite relative direction from what you'd do in a car. This is still true on a bicycle at 1mph.


I'm no physicist, but it seems the intuitive reason countersteering works is because when you turn, e.g. left, your center of mass also moves left because you need to lean left in order to turn. So if you turn left on your own this will move your center of mass left. And if you turn too sharply left your center of mass will be so far out that you will fall over. So turning right very quickly before turning left means that your center of mass suddenly shifts massively right, and therefore you get some extra time turning left while your center of mass is still busy shifting from right to left?


I used to ride a bike with no hands. I was still able to countersteer! If I leaned to the left, the bike would lean to the right, the steering wheel would go right, then I could lean to the right into the turn.


The best way I've found to experience this is to first learn to ride with no hands. This works best at speed. You actually steer by shifting your weight, but the easiest way to learn is is to grip the seat with your thighs and think about turning the bike by trying to turn the seat.

Once you can stabilize a no-hands ride, try pushing on the handlebar with one finger. You will find the the bike turns in the opposite direction of what you would naively expect. The harder you push, the tighter the turn will be in the "wrong" direction.


Not fan of the term "countersteering". If you changed the mechanical direction that the handlebars rotated the front wheel I doubt anyone would bother to call it "prosteering".

A better way to think about this is that bikes turn by banking. The method of controlling the angle of bank does not map in a simple way to the direction of turn.


> The method of controlling the angle of bank does not map in a simple way to the direction of turn.

Sure it does! (Unless by "simple" you're ruling out derivatives). If your wheel angle is moving right, then your bank angle is increasing left (or IOW, your left turn is becoming sharper, left turn radius is decreasing). While your wheel angle is moving left, your bank angle is increasing right. Whenever you stop moving the wheel, your bank angle will stop changing and you will be in a constant radius turn.

> I doubt anyone would bother to call it "prosteering".

Not sure I understand this objection... there's no rule about symmetric or consistent prefixes. Lots of things called X have a counter-X (see also anti-X). Examples: counter-intuitive, counter-insurgency, counter-strike, counter-reformation, counter-current, etc.

Counter-steering is differentiating from steering. But there's no need to differentiate normal steering from steering, so we don't normally prefix things with "pro", unless you're talking about someone who advocates for something. I think there are a few counter-examples to that in physics though. :)

In motorcycle safety, it's rather important to call out the counter-intuitiveness of counter-steering. People's reflexes tend to do the wrong thing in tight situations where quick steering is needed. If you need to turn right very quickly and haven't learned counter-steering, you can injure yourself by trying to steer right, and many people have.

It's pretty common for riders who haven't learned counter-steering to believe that leaning hard will be sufficient, and/or that body lean is as or more important than steering. But to turn very quickly, knowing about and being able to counter-steer is incredibly important.


Do you have a better single word or short phrase to describe it though?


Well the aviation people, who also control vehicles that are controlled by banking, don't bother to come up with a special name. When teaching people to fly they first teach how the controls can be used to control the attitude of the vehicle (roll, pitch, yaw are the terms that are used). Then they start a whole new discussion of how various attitudes will affect where the vehicle will end up.

Some things can't really be simplified (and perhaps shouldn't be).


On a bike, even at speed you can initiate a turn by simply leaning on the side.


The front wheel still kicks out in the opposite direction and counter steers for you due to the natural stabilizing properties of the bike


You can, but it's not very effective.

This 3 minute video explains how important counter-steering is with some actual experiments: https://www.youtube.com/watch?v=JWuTcJcqAng


Easiest way to try/prove this is ride without holding handlebars. You can turn corners easily.

Limits (compared to regular turning) are your lowest speed is higher (where you'd lose balance without holding handlebars) and the fact your center of gravity and stability are messed up (can't turn as tightly). And self preservation of course.


See 2:33 in this video: https://www.youtube.com/watch?v=JWuTcJcqAng&t=2m33s

Turning by leaning only works at all because when you lean it causes the handlebars to countersteer.

To prove it, lock your handlebars so that they can only point straight forwards, and then see how easy it is to steer. It's practically impossible.


> To prove it, lock your handlebars

It's impossible to start going straight even. The point was that leaning will initiate the turn (no limits on method).


> Turning by leaning only works at all because when you lean it causes the handlebars to countersteer.

That's totaly not my experience.


With all due respect, your experience, internet denizen, is overruled by reported experiment. See the video linked above.


It's experience vs reported experiment, I don't see how one is can overrule the other. I'll check the video later.


You're right, "overrule" is probably too strong a term.

I meant it more as a comparison between anecdotal evidence vs research evidence. I.e., someone saying "I've never seen a fire, I'm not sure why we need to bother with fire drills."

Maybe better would be "why bother getting vaccinations, I've never seen a bacteria in my life."


I've watched the video linked above in the thread and I admit that I was wrong, that I would countersteer when riding a bike, it's just that I don't realize it.

There's just one thing that I don't understand: on a bike, with the hands of the handlebar, I can turn right by leaning right, but I don't understand how leaning right would cause the countersteer left.


It should be recognized that you were willing to admit you were wrong - personally I find nothing in the world harder to do, let alone on the internet. That's awesome.

Here's another video that helped it click for me when I didn't get it either https://www.youtube.com/watch?v=PgUOOwnZcDU It's more "phsyics-ey"

When your hands are off the handlebar and you "lean right," the handlebars won't visibly "turn left," and if they do it will only be for the briefest moment. It only takes the tiniest countersteer to cause the "lean angle." It has to happen because your handlebars are non-rigid.

Let me know what you think after the video above. IIRC it has the "rolling cup" example, which for me works best.


Yeah it was hard to admit I was wrong.

I watched the video above and another one and I'm getting it a little better. Also another thing is that recently I've been riding a bike rather slowly, at speed where countersteering is not necessary and less visible, as shown in another video (https://www.youtube.com/watch?v=C848R9xWrjc). And as for countersteering while the hands off the handlebars, I realise that usually my eyes are on the road, not the handlebars, so I'd easily miss the brief countersteering.

Thank you for your patience too!


I've done a lot of riding without holding handlebars, so that's how I learned this.

Another limits is that you've got a delay to reach the brakes, which can make it dangerous for others in addition to yourself. And I agree that having your center of gravity moved up really mess up your stability.


Only if you've got a stupid racing bike with only hand brakes. Coaster/foot/back-pedal brakes are standard issue around these parts, and I wouldn't ever want to ride a bike without one.


Depends on how you ride. An adult in the US, you're on a road bike bent over the bars and going 15-20mph. Hands on the brakes at all times. I do a ride every summer with 20,000 like-minded people and if you see even one bike with coaster brakes all week its unusual.


Europe is full of city bikes with coaster brakes. Everybody here has a bike, not just the hard-core bikers.


I've rarely seen coaster brakes, especially among the non hard-core bikers here in Paris.


I don't know if all 20,000 people are hard-core. Its just that road bikes are very, very common. Kids bikes might have coaster breaks, sure. But hardly anybody over 15 has one.


You don't have hipsters in your town?


they ride fat -tire or fixie bikes :)


Brakes on rear wheels only are relatively ineffective, so I don't understand why you would prefer them. Unless there is such a thing as a front wheel pedal brake, which I have never heard of.


Why is hand brakes stupid? Much better control/modulation, especially with hydraulic disc brakes.


Rim brakes either grip too hard or not enough, and sometimes don't work very well in rain, and need regular maintenance and replacement. Coaster brake supplemented by hand brakes for emergency stops just feels safer and more in control in traffic situations.


Unless your feet are on the pedals wrong...


> stupid racing bike with only hand brakes

Or cheap basic road bike.


It's very easy to try. Go up to speed (20 km/h or so) and press on a handlebar, away from you. You will "turn" to that side even though the handlebars are moving in the opposite direction.


Here's how I explained countersteering to myself: To turn left, I need to lean left. The easiest way to lean left is to pull the bottom of the bike, where the wheels touch the ground, to the right.


I've wondered if following a painted line on a road with your bike is an example of Zen. The more I try to follow the line, the harder it is to stay on it. But when I stop trying/thinking about it, I have no problem staying on that line.


And if you don't take a moment to occasionally look up from the line to consider your surroundings, you might crash into an Uber.


Or a car


> Try following a straight marker on the road on your bike. It's very hard. When you start going too much to the right, you will find it impossible to actually nudge the bike back to the left, unless you accept that you have to go further to the right first.

Not true - you just have to shift your weight to the left.


I ride bike trials and have gotten good at keeping a straight line.

On a good day I can ride along the top of a handrail.

To keep a bike going straight at low speeds, you shift your weight, and by that I mean you swing your elbows or you knees, not your whole body.

You also can vary the sensitivity of the steering input by controlling how much of your weight is over the front wheel.

You can also use the front brake if you are deviating from your line. It allows you to push against the resistance generated to realign your center of mass.


> Not true - you just have to shift your weight to the left.

Not true - because of conservation of momentum (in the perpendicular direction) if you shift you weight to the left the bicycle will lean to the right and the center of mass will remain unchanged.

It's called countersteering, look it up.


I never thought I'd see people arguing against counter steering on HN, I left that up to youtube comments.


On the contrary, it doesn't surprise me at all. Many people on HN are young and successful which often means they overestimate how confident they should be in subjects outside their area of expertise. It's not just simple mechanics either, it's everything.

Didn't you see just yesterday that lunatic claiming that the "4-color map theory is bunk"? https://news.ycombinator.com/item?id=16862553


You look it up. Every article you'll find will point out that on a light vehicle like an bicycle you don't need to countersteer with the handlebars and can achieve the same effect by weight shifting. (Indeed the fact that it's possible to ride a bicycle without holding the handlebars at all should be all the proof that's necessary that one can navigate through weight shifting alone).


> You look it up. Every article you'll find will point out that on a light vehicle like an bicycle you don't need to countersteer with the handlebars and can achieve the same effect by weight shifting. (Indeed the fact that it's possible to ride a bicycle without holding the handlebars at all should be all the proof that's necessary that one can navigate through weight shifting alone).

What exactly is your claim? That you can turn left without touching the handlbars, or that you can turn left without first having the bicycle steer right?


> What exactly is your claim? That you can turn left without touching the handlbars, or that you can turn left without first having the bicycle steer right?

That you can turn left without having to "go right". If you tilt to the left by shifting your weight (and that's something I actually found almost impossible to do consciously - when I first learned to ride a recumbent I had to learn to weight shift before turning the handlebars all over again, for the same reason as people countersteer - when I tried to just turn with the handlebars I fell off, so I'm familiar with the effect we're talking about - but if you just lean to the left your body figures it out, or at least mine did) you'll turn to the left and follow the line just fine.


> That you can turn left without having to "go right".

Then you're wrong, and mixing handlebars into this is just you trying to obfuscate.

You claim that "Every article you'll find will point out that on a light vehicle like an bicycle you don't need to countersteer with the handlebars". I'm guessing you're regurgitating [0]. At least you looked it up like I suggested, respect. But it says that you don't need to countersteer with the handlebars because you can countersteer without the handlebars. You're still countersteering, as can be seen by the initial bump in the middle graph [1].

Anyway, like someone else said this is starting to look like YouTube comments.

[0] https://en.wikipedia.org/wiki/Countersteering#Countersteerin...

[1] https://en.wikipedia.org/wiki/File:Countersteer_response.JPG


> At least you looked it up like I suggested

Don't flatter yourself. I had read that article or another like it years ago.

> it says that you don't need to countersteer with the handlebars because you can countersteer without the handlebars.

You're right. I misunderstood, and I've learnt something - that explains why it was hard to lean over consciously. We'd've got here a lot sooner if you'd put half as much effort into engagement as you do into condescension.


[flagged]


You're not even pretending to be anything other than a troll any more. Believe what you like.


> ride a bicycle without holding the handlebars

That's because you're pedaling. If you stop pedaling, you can't.


I don't know if you meant "not moving forward", but I usually don't peddle when I make my hands-free turns. Coasting works fine.


Sure, but if we're talking about steering we're presumably talking about turning while pedalling and moving forwards.


> But try this: Try following a straight marker on the road on your bike. It's very hard. When you start going too much to the right, you will find it impossible to actually nudge the bike back to the left, unless you accept that you have to go further to the right first.

This holds in general for any motion where velocity is a continuous function of time, doesn't it?

Let f(t) be your deviation at time t perpendicular to the desired straight path, with positive to the right and negative to the left.

If you are "going too much to the right" at time t, e.g., f'(t) > 0, then because f' is continuous there must be some interval around t such that f' > 0 at all points in the interval. That means that f is strictly increasing throughout that interval, e.g., "you have to go further to the right first".


The explanation is that you need to balance out centrifugal force F=mv^2/r.

"Sharp turn" has smaller radius, therefore much larger the force. By turning in the opposite direction first, you're making the turn much less sharp, increasing the radius and thus reducing the force.


I've always thought of it like a plane, with the terms adverse yaw and adverse roll applying. The main difference is if your turn is uncoordinated, you fall over. Yaw is controlled via the handlebars. Roll is controlled via balance.

Just turning the handlebars causes adverse roll in the other direction. If you are falling to the left, turning the wheel to the right causes an opposite roll and restores balance.

Turning the handlebars the opposite way momentarily is a great way to start a turn because of the adverse roll that it causes.



I suspect running will similarly be difficult in a low gravity environment: proper technique in running is basically falling forward and your legs moving to continually prevent it. Without gravity to fall forward, it's probably very hard to move efficiently.


A few scifi authors have talked about this idea. I forget which book/author[0], but one of remember suggested that children born on the moon had naturally developed what was called a "kangaroo run" that let them move quickly, that immigrants from Earth couldn't copy well at all.

[0] One of you is about to tell me exactly the name and author now, aren't you?


You are thinking of the Red/Green/Blue Mars series by Kim Stanley Robinson.


That sounds about right. I loved the first two of those books.


"kangaroo run" certainly seems like a good description of the running technique the Apollo astronauts used to move around.


It’s not zero gravity but I recommend this video from an Apollo mission:

https://m.youtube.com/watch?v=HKdwcLytloU


Reminded me of this great Smarter Every Day video:

https://www.youtube.com/watch?v=MFzDaBzBlL0

(both interesting and funny)


This sounds very similar to the spinning dancer illusion [1] where your brain locks into a configuration where it can see it rotate in one way or the other, but you can't control when or which.

[1] https://en.wikipedia.org/wiki/Spinning_Dancer


I can control the direction. It kind of feels similar to 3D stereograms where the image just kind of 'snaps' into place, but in this case, she starts spinning the other direction. Kind of fun and quirky, and you really have to do it on purpose.


To provide a corroborating perspective on this, I learned to control this too, but it took a lot of practice to do it, and even now it's not 100% immediately effective for me.


Same here, not 100%. I actually just tried it on the spinning dancer, and the more I practiced, the better I got, but definitely not 100%. I bet I could get there with enough practice though.


I suspect you can ride it with a hack: either raise your center of gravity (to get into bike mode) or lower it (to get into trike mode).


Or simply turn at lower speeds/make less sharp turns as they still had some control. It would simply have made a less interesting video.

Similarly with the zero gee pendulum keep going far enough and the end would move to the left as it's only so long. Then reverse the process to move the pendulum to an arbitrary position. Alternatively, use vastly slower motions and the friction with the arm will counteract tiny momentum changes.


First of all without gravity and weight wheels won't get grip on the road, so no matter if it's a bicycle, tricycle, or a regular car - you can't drive it in 0 gravity, it will just jump away from the road.


Yes but ignoring that, or using magnetic wheels, you still can't steer it.


If you have a force pushing it onto the road wouldn't that suffice to make it steerable?


You also need some way to counter the centripetal acceleration. The training wheels do that in the tricycle, and leaning does it in a bicycle, but you need gravity for leaning, so in zero g with magnetic wheels&track you could not steer a bike the normal way, and perhaps not at all, but you could steer a tricycle.


This is not what they mean by zero gravity in the video.


Cars emit exhaust, that thrust however small could be used to move the car around. Granted not quickly.


Cars require oxygen to operate, there's no oxygen in space.


Nobody said anything about "space." "Zero gravity" (or microgravity, anyway) doesn't imply a vacuum.


Interesting read as wel, link in first answer etc: basically, the exact physics between why cycling even works, seem yet to be a bit unclear: https://bicycles.stackexchange.com/questions/4656/what-makes...


This is a very interesting video that debunks some common theories of how the bicycle balancing works, and also proposes some extra insights (although no definitive theory yet)

https://m.youtube.com/watch?v=NcZCzr9ExKk

Also see this one for extra footage of the Gyroless, "trail-less" TMS bicycle that still manages to balance itslef

https://m.youtube.com/watch?v=LbeENKn5kZU


Am I the only one who thought throughout; "I could turn that thing, just drag your foot across the outer most wheel in the direction you want to turn." Let the friction, and unequal spinning speeds to the work.

(The wheels can't be locked to each other, otherwise that would also cause the bricycle to be unable to turn, thus invalidating the whole experiment.)


The wheels certainly can be locked to each other, that's how standard kid tricycles work - all it means that in turns some slipping/friction is inevitable.


Can someone explain to me why the authors neglect to mention nutation and precession on a vehicle that consists of non-negligible spinning masses? I don't get it.


Really highlights how you have to throw a bike slightly into the opposite direction[0] to a turn in order to get it to turn. When she tries to do this in the zero-gravity mode the bike just rolls over in the opposite direction without being able to kick the front wheel into the turn.

[0] https://www.youtube.com/watch?v=llRkf1fnNDM


Fascinating. This is the content I enjoy seeing most.


A bicycle on the moon on the other hand... now that would be fun


Or even better, an aerocycle - human-powered flight is almost impossible on Earth, but in 1/6 g you could do some very fun stuff.

IIRC, Arthur C Clarke mentioned races of that sort of vehicle in one of his works, so credit to him.


In Kim Stanley Robinson Mars trilogy, one of the characters talks about being on one of Mars's moons, and how they had to be careful because a good running start could get you to escape velocity.


The escape velocity of Deimos is only 20 km/h (~12 mph) but I'm not sure how well running would work in such low gravity.


Wouldn't that require a thicker atmosphere?


Well, it IS perfectly ridable, but unsteerable. You need a straight road. Bicycles in space are still usable, as long as you just go ahead, e.g. as the jogger in Kubrick's 2001.


> You need a straight road

You should be able to turn if the road were curved, e.g., a velodrome (https://imgur.com/gallery/YqbXa)


I would still love to try that out by myself. I have the theory that by going extremely slowly you could successfully steer a bit. The problem is only the centrifugal force.


I feel like learning to steer it would be just as possible as learning to ride a bike you steer and pedal in reverse. You just need to get past your muscle memory.


Unless I'm misunderstanding the physics, it would be quite literally impossible, not a matter of learning - any attemp to steer results in the angle of the bike moving in the opposite direction an amount directly proportional to the change in direction, and with gravity being cancelled out by the spring (or in 0G), there is no way to rectify the tilt except by steering back to the original course.

Technically, you can steer temporarily - if steering right by 20° tilts you to 45°, you can ride at 45° (actually, it's possible that a 45° turn would always relate to a 45° tilt - I'd need to think on it), however your allowed directions are determined entirely by your starting direction; if you started pointing South, there would be no possible way to move North, and would likely only be able to operate the bike in the 160° - 200° range, looking at the video.


I believe you are correct, based on the video.

Mathematically, with the usual simplifications and restrictions we mean by that, the device can not be steered freely at all.

Practically, if you were left in a room with the device alone for a while, you'd probably find some way to change its direction. My initial guess is to jerk it up as high as possible and then jerk it sideways and rebalance. It's pretty heavy, so this isn't going to work very well and will be very exhausting. However, I suspect the ultimate technique you'd settle on would work just as well if we locked the front wheel entirely so it couldn't be turned, so while you may be able to "direct" the device you would still arguably not be "steering" it.


Heck, you might turn slowly if you just rode around tilted, due to the way the tires deform - although I've nowhere near enough familiarity with tire physics to know which direction.


Yup. There's probably a lot of little such things where the model deviates from reality. Might be a way to exploit the friction in the various hinges, etc. It may be easier to turn on a low-friction surface where the ground friction doesn't overwhelm these effects, etc. Fun to play with, but the end result is still that even if the real world doesn't give us a "truly" unsteerable bike, I am still surprised that this curve between "steerable bike" and "steerable trike" passes near "zero steerability" at all. I would not have guessed that.


The biggest problem with turning in zero gravity is there's no other force than forward momentum.

The only thing that keeps bicycles upright in gravity is forward momentum. If a bicycle in gravity with no rider tried to turn right on its own, it would fall over. Only if the road curves naturally to the right will it follow and not fall over.

Imagine no bike. You're floating forward in zero-G. Now you want to go right. You turn to the right.... but you're still going forward. It's like that, but on the bike. Nothing is keeping you stuck to the ground, so no matter how you try to move the bike, it will want to keep going in the original direction of momentum, and you will just end up tumbling over if you try to turn the wheel or lean anywhere.

Another way to look at it, just like in the video: if you are tilted, you keep going forward, while tilted. You would literally need some force to pull you in a direction other than forward in order to turn without tumbling toward your original direction.

With a tricycle, when you turn the wheel, the inside wheel is essentially anchored to the ground where it is, and the outside wheel follows the only path that it can, since it can no longer continue going forward. If you were going fast enough during this turn, the whole thing would tip over, similar to how cars in gravity will flip over when they try to turn too fast. Momentum just carries them forward.


It doesn't seem like you watched the whole video, where they explain the "why."


That clip (and the research paper) is from 2014. Should a year tag be added to the headline?


Title is misleading.

A 'bricycle' in zero gravity is unsteerable


Surely is shows that a bricycle in earth gravity is unsteerable.


A bricycle is a bicycle in zero gravity.

Should be "a bicycle in zero gravity is unsteerable".


Actually, I'm pretty sure it'll be unridable too. But you're right, the video isn't about that.


Discovery Channels Mythbusters tested if one could cycle underwater, which failed too.


Why is she not wearing any type of safety gear / a helmet?!


Dunno, people probably do actual gymnastics in that gym with no safety equipment at all.

I suspect that there is some sort of cultural thing here where it feels more dangerous because someone is touching a bicycle. In particular it is probably some sort of car culture thing. In such a culture there is a tendency to aggressively ignore the danger of cars. That seems to cause a tendency to overestimate the danger of other transportation modes.


She's in a large room with no other traffic, and not going fast at all. The risk of anything is extremely low.


My coworkers dad died from falling off a bike in his driveway at zero speed. He had no helmet and hit his head on the pavement and instantly died.


People get struck by lightning too.


Do you wear a helmet to work? Much more dangerous environment as the statistics show.


More dangerous than riding a bike? I exceedingly doubt that, could you link those statistics?


Not sure about how unsafe offices are but here is a paper showing statistics about how it is safer to ride a bike than to not ride one. As in "[cycling has] shown beneficial effects on population risk of all-cause mortality (ACM)": https://www.ncbi.nlm.nih.gov/pubmed/25344355/


Huh, that's an interesting result, though perhaps not entirely unexpected. Another aggregate study can be found at [1].

I still suspect that the difference in risk between biking without a helmet and with a helmet is significant, and that the studies aggregated likely had a majority of riders using helmets (this is entirely based on subjective experience of US cyclist helmet-wearing probabilities, so let me know if that's wrong).


I'm not sure, but I do know that in the Netherlands no one bikes with a helmet, and it's considered very safe: I took the bicycle to school ever since mid primary school (we don't have school busses or anythig like that.) The only people that I ever see wearing helmets on bicycles are North American tourists.


I guess it depends heavily on the locale - I live in Portland, and while we're one of the most bike-friendly cities in the US, going helmetless would be risky at best, though outside city limits wouldn't be as concerning.


Yep, your head will crack open from a four foot drop at any speed. And how about a helmet where the strap is actually clipped and tightened?


Hope they don't play any kind of sports in that sports room they're testing in then!


Bikes are risky in that sense. Your legs and arms can't mitigate a fall like they usually do. And testing an experimental bike with a bunch of extra metal to find out how it fails? Even worse.

Besides, the point of the experiment is to test the bike. There's nothing gained by not wearing a helmet. You're also implying that those other sports wouldn't be better with helmets, which may not be true.


>Bikes are risky in that sense. Your legs and arms can't mitigate a fall like they usually do.

The way to handle most falls if you can anticipate them is to jump straight up and off the bike.

[1] https://www.youtube.com/watch?v=ZcCGDr9f1L8


> Yep, your head will crack open from a four foot drop at any speed.

I highly doubt this. The amount of force required to crack a human head open seems to be much more than what you can generate in 4 feet of free-fall.


I don't watch Youtube, so it's hard to assess the point being made, but zero gravity implies no normal force and therefore friction. Bicycles need friction for both drive and steering, as I and many others have painfully experienced!


Which is why you'll miss the point that "the bicycle is, for balance purposes, effectively in zero gravity".

It's actually a really fascinating clip — though I suspect you're not going to watch it. For anyone else, you can start here to see it in action.

https://youtu.be/rNQdSfgJDNM?t=1m

The original video is only 3 minutes long.


Maybe skip commenting on YouTube videos that you refuse to watch? I'm sure there must be a rule here about commenting without rtfa?


Actually the rule (guideline) is the inverse:

"Please don't insinuate that someone hasn't read an article. "Did you even read the article? It mentions that" can be shortened to "The article mentions that." "

It's fine to comment without reading/viewing the submission, and I'm sure many of us do :)

Although, I am curious as to why kikoreis doesn't use YouTube?


> Please don't insinuate that someone hasn't read an article

Sure, but if they explicitly say they haven't read it, then make a wrong assumption about it, surely you can call them out


I don't see any rule supporting that conclusion.


That's not how it works, there's no rule stating you can't do it.


I don't see any rule allowing you to comment on whether any rules support a conclusion.


> It's fine to comment without reading/viewing the submission, and I'm sure many of us do :)

That lack of a written guideline does not make it okay or a good idea to comment on the article based only on the headline like the GP did. Fine if you're responding to other people on other topics, but positing a straw man argument against your imagination of the article's contents without reading it, the comment will be rightly downvoted.

The guideline you posted is not the inverse, the guideline you posted is suggesting it's best to not make assumptions. Posting about the article content without viewing it is making assumptions.


It's not insinuating if it was already stated by the person you're responding to. Notice also how in the example there is a question "Did you read the article?", in the comment you reply to there is also a question, but neither of them insinuates something (well, the second maybe insinuates that the user is doing something against the rules, but I can't really see any rule explicitly ruling that out)





Applications are open for YC Summer 2019

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact

Search: