
Uncontrollability of a bricycle (2014) [video] - gballan
https://m.youtube.com/watch?v=rNQdSfgJDNM
======
torrance
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](https://youtu.be/MFzDaBzBlL0)

~~~
maaaats
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.

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

~~~
maaaats
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](https://www.youtube.com/watch?v=kUiiJI_tPVk)

~~~
kaybe
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.

~~~
avar
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.

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

~~~
antoineMoPa
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](https://www.youtube.com/watch?v=5WrGJ8A0Y1o)

------
maaaats
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.

~~~
Adirael
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](https://en.wikipedia.org/wiki/Countersteering)

~~~
NLips
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.

~~~
ozim
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.

~~~
baud147258
> countersteering is always required

Only on a motorbike.

~~~
jstanley
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.

~~~
baud147258
> 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

~~~
scatters
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.

~~~
baud147258
That's weird since I don't think I'm countersteering when turning.

Or perhaps I'm doing it unconsciously?

~~~
function_seven
> 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.

~~~
baud147258
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.

~~~
schoen
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.

~~~
baud147258
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.

------
gballan
Paper is here:
[http://ruina.tam.cornell.edu/research/topics/bicycle_mechani...](http://ruina.tam.cornell.edu/research/topics/bicycle_mechanics/overview.html)

------
Moodles
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.

~~~
mabbo
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?

~~~
cecilpl2
You are thinking of the Red/Green/Blue Mars series by Kim Stanley Robinson.

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

------
amelius
Reminded me of this great Smarter Every Day video:

[https://www.youtube.com/watch?v=MFzDaBzBlL0](https://www.youtube.com/watch?v=MFzDaBzBlL0)

(both interesting and funny)

~~~
rootlocus
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](https://en.wikipedia.org/wiki/Spinning_Dancer)

~~~
loco5niner
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.

~~~
lenocinor
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.

~~~
loco5niner
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.

------
tlb
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).

~~~
Retric
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.

------
ajuc
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.

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

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

~~~
cryptonector
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.

------
stinos
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...](https://bicycles.stackexchange.com/questions/4656/what-makes-a-bike-
stay-upright-when-moving)

~~~
glaberficken
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](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](https://m.youtube.com/watch?v=LbeENKn5kZU)

------
grayhatter
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.)

~~~
PeterisP
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.

------
gmueckl
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.

------
monkeynotes
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](https://www.youtube.com/watch?v=llRkf1fnNDM)

------
nightcracker
Fascinating. This is the content I enjoy seeing most.

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

~~~
larkeith
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.

~~~
djsumdog
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.

~~~
sesutton
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.

------
rurban
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.

~~~
jowsie
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.

~~~
larkeith
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.

~~~
jerf
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.

~~~
larkeith
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.

~~~
jerf
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.

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

------
ageofwant
Title is misleading.

A 'bricycle' in zero gravity is _unsteerable_

~~~
nicky0
Surely is shows that a bricycle in _earth_ gravity is unsteerable.

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

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

~~~
jrootabega
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?

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

~~~
jrootabega
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.

~~~
gerbilly
>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](https://www.youtube.com/watch?v=ZcCGDr9f1L8)

------
kikoreis
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!

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

~~~
Jaruzel
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?

~~~
shawabawa3
> 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

~~~
freeloop10
I don't see any rule supporting that conclusion.

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

