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/sci/ - Science & Math

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File: 34 KB, 493x294, bicycle-yellow.png [View same] [iqdb] [saucenao] [google]
1756621 No.1756621 [Reply] [Original]

fucking bicycles how do they work?

>> No.1756627

Which part exactly is confusing you?

>> No.1756632

>>1756627
how something unbalanced while stationary becomes balanced when moving.

>> No.1756643

gyroscopic stability

>> No.1756648

>>1756632
That's because the wheels are moving.

>> No.1756654

>>1756643
Although I feel it must be pointed out that gyroscopic stability counts for nothing if the rider isn't on the bycicle.

Unless it's going at an incredibly unsafe speed I guess.

>> No.1756657

>>1756648
how moving wheels can grant balance?

>> No.1756658

>>1756632
But when I'm not moving on a bike I can balance it with my weight.

That's probably different though.

What about unicycles? Same concept?

>> No.1756659

You are now aware a bicycle hangs from the top of its tires

>> No.1756668
File: 76 KB, 613x885, balancing-act-001.jpg [View same] [iqdb] [saucenao] [google]
1756668

>>1756632
Its commonly suggested that the wheels act like gyroscopes, but that's been disproved.

The answer is: Humans are just really fucking good at balancing on things. With some practice we can keep our balance on just about anything.. It gets to the point where you don't even think about it.

>> No.1756670

>>1756659
no it doesn't you retard. Its supported by the bottom of the tire with the spokes.

>> No.1756673

>>1756658
More or less, obviously unicycles have to be balanced in another direction by the rider, but the gyroscoping stability doesn't really do much, it's all about the rider shifting the bike under him to keep it upright.

>>1756659
Top of the tyres is misleading, top of the wheels is more like it.

>> No.1756675

>>1756668
you got THAT shit right on

have they got a robot to ride a bike yet?

>> No.1756683

>>1756675
Yeah, not very well, but they're able to keep some degree of balance.

>> No.1756688

>>1756668
Care to source that ridiculous statement?

>> No.1756685

>>1756683
fucking magnets, they got a lot to answer for

>> No.1756692

>>1756688
Which ridiculous statement, that the wheels don't act as gyroscopes?

If you're calling him out on that, you've clearly never ridden a bike before.

And that's just sad.

>> No.1756700

When the back wheel accelerates the frame, the front wheel readjusts to reduce friction (straightening it).

>> No.1756703
File: 133 KB, 354x363, feels-good-man.png [View same] [iqdb] [saucenao] [google]
1756703

>>1756688
>>1756692
Got my source right here: http://socrates.berkeley.edu/~fajans/Teaching/MoreBikeFiles/JonesBikeBW.pdf

Cancelled out the gyroscopic effect and the bike was still rideable. Lick my science balls.

>> No.1756710

>>1756692
saying it's not a factor just "because humans are good at balancing" is not an argument.

try riding a bike really slowly with no hands, you'd need really REALLY good balance. Now try it when you are moving at a decent speed, it's easy.

>> No.1756711

Real answer:

Yes the wheels act as gyroscopes, but have such a small moment of inertia that this is insignificant in balancing.

The bike balances because the rider makes tiny adjustments with the front wheel to keep it beneath the centre of mass. The faster the bike goes, the smaller the adjustment needs to be, so balance becomes easier.

>> No.1756715

>>1756668
http://www.youtube.com/watch?v=8H98BgRzpOM

>> No.1756716

>>1756700
then how unicycles work?

>> No.1756717
File: 145 KB, 477x611, 1270787342089.png [View same] [iqdb] [saucenao] [google]
1756717

>>1756700
How so? Is the middle of the tire easier to bend than the sides, and does that effect balance?

>> No.1756721

>>1756710
>with no hands

Uh, why no hands? My hands aren't gyroscopic forces, but the front wheel turning under pressure from the ground and locking at 90 degrees will really fuck things up.

The fact I can ride really slowly WITH my hands surely proves the gyroscopic effects are irrelevant.

>> No.1756719
File: 236 KB, 887x1296, track_stand_atlanta_cm.jpg [View same] [iqdb] [saucenao] [google]
1756719

>>1756710
Learn2Trackstand.

>> No.1756720

i wonder why the invention of bicycle took that long to invent. ancient greeks had everything they needed to build one.

>> No.1756724

>>1756720
>i wonder why the invention of bicycle took that long to invent.
i definitely need some sleep.

>> No.1756726

>>1756720
I had no idea the greeks had such advanced rubbermaking technology.

>> No.1756728

>>1756721
That's because without your hands you are relying on the gyroscopic effects far more

>> No.1756729

>>1756726
1st bicycles made didn't have rubber tires. they would be uncomfortable, but work nevertheless

>> No.1756730

>>1756724

Well the gear/sprocket combination is a problem. I don't believe they had the tools to produce strong enough and sufficiently precise parts.

If they did I would like to know.

>> No.1756731

>>1756728
You're saying that there are gyroscopic effects when I'm riding under a mile an hour?

You really HAVE never ridden a bike have you?

>> No.1756733

>>1756711
Tyres spin very very fast, try taking a bike wheel/axle off, spin it quickly with your hand then grip the two sides of the axle. Now try to tip it to the sides. And that's just you spinning it with your hands, the tyres go alot faster when you are peddelling.

>> No.1756738

>>1756730
1st bicycles didn't have that too, you turned front wheel directly. gears are a later addition.

>> No.1756740

>>1756733
It's not enough force to keep the full weight of a person balanced on an inherently unstable platform, not at the speeds most people will reach, and certainly not at the minimum speed you have to travel to keep upright.

>> No.1756741
File: 39 KB, 392x348, bicycle.gif [View same] [iqdb] [saucenao] [google]
1756741

>>1756738
forgot my pic.

>> No.1756743

>>1756738
>>1756741
I'd imagine then that it wasn't a case of why they didn't, but why they would.

Even if they'd made the device with sensible proportions, the method of transport would still be far slower and less adaptable than a man on a horse.

>> No.1756745

>>1756731
Yes there are gyroscopic effects, but that's not waht I'm saying.

I'm saying when you go slowly there is little gyrocopic effect, so riding without your hands and the ability to use your good balance it's almost impossible to stay upright

BUT riding fast means large gryoscopic effects come into play, so you can easily ride without having to use your hands to balance yourself.

God dammit are you fucking retarded? Read my post again.

>> No.1756747

>>1756740
do that little experiment, actually go outside and do it now so you understand just how powerful the effect is.

>> No.1756748

>>1756738

Oh wow, that must have been a pain to ride.

>> No.1756750

>>1756743
>man on a horse.
they didn't have stirrups back then, so a man riding a horse was not that much different than a cowboy riding a buffalo in rodeos. bicycles would be equal at least, if not superior.

>> No.1756752

>>1756745
>riding without your hands and the ability to use your good balance

If I was unable to use my hands, or my good balance, and going at 50 miles per hour I'd still be off that bike in seconds.

Your argument does nothing to indicate that gyroscopic effects are in any way important.

>> No.1756753

imagine a bike with motorised wheels but no rider

the motors start the wheels turn round

how long does it stay upright for?

>> No.1756754

Your forward momentum along the path of the wheels keeps you preferentially moving in that direction.

Your inertia resists change in your direction of motion, which makes it easier to maintain that heading and reduces the effort required to avoid tipping or veering off-course.

The gyroscopic effect of the wheels is not a major factor.

>> No.1756755

>>1756750
How good were their roads though, and how agonizing would a penny farthing be to ride over cobbles?

>> No.1756756

>>1756750
I can't imagine greek roads being nice a smooth, they'd probably be a tough ride even with a mountain bike. Let alone a bike made without air filled rubber tires, no gears bearings or decent lubrication.

>> No.1756760

>>1756752
read this
>>1756747


YOU DO NOT NEED TO BE RIDING SUPERFAST TO GET POWERFUL GYROSCOPIC EFFECTS

>> No.1756762
File: 7 KB, 399x349, bike.gif [View same] [iqdb] [saucenao] [google]
1756762

bikes don't have any significant gyroscopic effects. if you don't believe me try removing a bike front wheel and bearing and holding it with your hands while someone spins it really fast. it will hardly have any gyro action; they just aren't heavy enough and don't spin fast enough.

the reason why bikes are stable is that the pivot point of the front wheel is in front of where the wheel contacts the ground, so the front wheel is "pulled" straight if you aren't actively turning.

if you want to test this out, try pushing a bike forwards. if you turn the handlebars a bit and keep pushing, it will self correct and straighten the wheel. but if you push the bike backwards, the effect will be inverted and if you don't keep the handlebars straight it becomes unstable and tries to turn hard in one direction.

>> No.1756764

>>1756760
Ok.

I'm riding along at 5mph, I'm not allowed to use my hands or my ability to balance, how long do you imagine I'll stay on there?

3mph, 10, 1000?

Your argument is flawed, read what you are trying to tell me, and stop getting annoyed because I'm not aware of what you're not saying.

>> No.1756767
File: 74 KB, 1290x987, Untitled-3.png [View same] [iqdb] [saucenao] [google]
1756767

Thoughts?
The higher pressure areas would resist, so it'd be easier for the bicycle to tip back to the low pressure areas.

>> No.1756769

>>1756767
and by pressure, I mean, compaction of the rubber, not air pressure inside the tube.

can someone take a torus into a stress testing program and show us what happens when it sits on a hard surface?

>> No.1756771

>>1756755
you have a point there, one shouldn't expect a proper road until Romans. but still, one would expect an experiment or two. fucking Archimedes imagined some crazy shit, a bicycle is pale compared to that.

>> No.1756772

>>1756767
I'd love to call you out as a troll, but you've really put a lot of time into that little diagram haven't you?

It's a very nice diagram.

>> No.1756770

>>1756764
Not very long, because riding at 5mph doesn't produce significantly powerful effects to keep you easily balanced. That's the point I've been making, fucking hell it's like talking to a brick wall.

I'm not saying it's the ONLY reason the bike is more stable at higher speeds, but it's a major factor.

>> No.1756776

>>1756770
Now we're getting somewhere.

It's not a fucking major factor at all, you accept that I'm going to fall off at 10 miles per hour, at 5 miles per hour, at 50 miles per hour, all if I'm not allowed to use my hands or ability to balance.

So how fast do I have to be going for the gyroscopic forces to keep me on there for any length of time?

The gyroscopic effect is negligible.

>> No.1756780

>>1756771
The vast majority of items from those times will no longer exist, I wouldn't be in the slightest bit suprised if some form of bicycle was a common child's toy in various unconnected periods.

>> No.1756781

>>1756719
Doesn't work on most common bikes because they have freewheel cog sets that will just spin the chain when you push backward.

>> No.1756782
File: 72 KB, 665x483, Untitled.jpg [View same] [iqdb] [saucenao] [google]
1756782

http://www.youtube.com/watch?v=HHIWv6Dx93w
>Self balancing motorcycle

>> No.1756783
File: 16 KB, 124x119, y2ibuzjl.png [View same] [iqdb] [saucenao] [google]
1756783

>>1756772
>It's a very nice diagram.

it's so nice I think he deserves a gold star! :-D

>> No.1756785

>>1756772
Just because I'm wrong doesn't mean I'm a troll. Its just an idea, sheesh.

>> No.1756786

>>1756776
I can't give you a cutoff, just use some commong sense, it's easier to ride with no hands the faster you go.

But you clearly aren't listening to reason, so beleive whatever you want you ignroant goose.

>> No.1756789

>>1756782
a 3rd tire would be much more efficient solution.

>> No.1756792

>>1756786
>it's easier to ride with no hands the faster you go.

Right, but riding without using your hands OR your balance, you're going to have to break the speed limit in any country on earth to remain upright for any length of time.

I am listening to everything you say, and trying to point out why your argument is flawed. without being able to balance myself, I will be unable to ride the bicycle, they gyroscopic effects have little to no part to play in keeping me on a bike.

>> No.1756795
File: 30 KB, 1210x769, Untitled-3.png [View same] [iqdb] [saucenao] [google]
1756795

>>1756783
Fine, how about this then?

>> No.1756797
File: 26 KB, 447x365, Untitled-4.jpg [View same] [iqdb] [saucenao] [google]
1756797

>>1756789
Yeah, because thats just as cool. . .

>> No.1756799

>>1756795
I preferred your first, and I'm afraid you're still way off.

Sit on a stationary bicycle next tome you get the chance and pivot it. They actually design tyres to avoid this type of thing, because it would hinder your ability to maintain your balance, you need the bike to tip slightly from one side to the other, and it's much easier to maintain stability if it does this in a predictable way.

>> No.1756800

Human intervention has to be pretty irrelevant, because rolling a coin is easier than standing it on its edge

>> No.1756801

>>1756792
the wheel doesn't self correct to move back upright. even when you ride with no hands you can still correct your balance with your ass and legs, it's just nowhere near as precise as using the handlebars. And again, a large gyroscopic force means that any movements will be far more difficult, so you have more time and more leeway balancing and counterbalancing.

>> No.1756804
File: 88 KB, 247x248, 1284068960839.png [View same] [iqdb] [saucenao] [google]
1756804

>My face when i first discovered that actually turning the handle bar results in the bike turning the other direction you'd expect it to

>> No.1756805

>>1756801
>you can still correct your balance with your ass and legs

>so riding without your hands and the ability to use your good balance

You're losing track of your argument, how about you stop, read; >>1756703 and come back?

>> No.1756808
File: 24 KB, 387x259, 1266158611666.jpg [View same] [iqdb] [saucenao] [google]
1756808

>>1756805
>you can still correct your balance with your ass and legs, it's just nowhere near as precise as using the handlebars

from >>1756801

>> No.1756809

imagine a bike with motorised wheels and no rider (mass added to compensate)

the motors start the wheels turn round

how long does it stay upright for?

still waiting for an answer, my instinct and it is only instinct, is that the bike topples over in a few metres or less

>> No.1756811

>>1756805
I cannot pdf, did they weld the handlebars so you can't turn?

>> No.1756812

>>1756809
But you can roll a quarter for quite a ways

>> No.1756817

>>1756809
I've fallen off my peewee 50 as a kid and it's gone rolled a good 100 meters down a hill, it only stopped when it went straight through a corner and crashed into a fence.

>> No.1756818

You can roll a marble infinitely far without it falling over

>> No.1756819

>>1756804
Countersteering is a good example how "common sense" is overrated
http://en.wikipedia.org/wiki/Countersteering

>> No.1756820

>>1756817
It's a lot more stable without your fat ass on top of it!

(I kid, I know you /sci/ dweebs are skinny as fuck. :P)

>> No.1756821

Can someone explain to me why I can be too drunk to walk but still ride a bicycle?

>> No.1756823

>>1756811
You can't PDF, and I can't fucking website, is it down?

>>1756703
What science did they do to the bicycle mister happy frog?

>> No.1756827

>>1756821
police carried you and bicycle back to your home, you were too drunk to remember.

>> No.1756832

>>1756823
nm, it worked. No abstract though, so fuck it

>> No.1756835

>>1756821
Shit's dangerous. I was really fucking stoned a few weeks ago riding home at 3am down the middle of the road. I closed my eyes and took a deep breath in, appreciating the wind and smells. I opened my eyes just before I rode into one of the big square cubs, faceplanted on someones front lawn.

>> No.1756845
File: 619 KB, 808x582, Screenshot-4.png [View same] [iqdb] [saucenao] [google]
1756845

>>1756823
What the prof did was mathematically work out the dynamics system to prove that the gyroscopic effect of the wheels is so small it provides essentially zero stability.

He proved this experimentally by getting a second set of wheels spinning in the opposite direction; cancelling out all gyroscopic affects. He did not observe any change in his ability to balance at any speed.

>> No.1756863

>>1756845
>a second set of wheels spinning in the opposite direction; cancelling out all gyroscopic affects.

Apparently my understanding of gyroscopic effects is even shakier than I thought.

>> No.1756867

>>1756621
Can fucking someone explain this "gyroscopic effect" in plain English.
Also explain how this all works in layman's terms.

>> No.1756898
File: 154 KB, 404x358, Screenshot-12.png [View same] [iqdb] [saucenao] [google]
1756898

fucking troll threads, how do they work?

>> No.1756904

>>1756898
So we should avoid discussiong any form of science, and just stick to helping kids out with their homework?

>> No.1756943

>>1756904
he is either a low level troll, or posts these reflexively when he sees fucking and work in same sentence.

>>1756867
I support that notion

>> No.1757147

Bump!

>> No.1757157

>>1756819
Ever since I learned about countersteering I've been trying to observe myself doing it... but I just can't.

>> No.1757213

I haven't bothered to read the troll thread.

But my understanding is that its easier to make corrections the faster you're going. If you try and balance the bike at less than walking pace you swerve all over the place. But at speed all you do is slight turn the handlebars to the side to keep the wheels under you. Notice when you turn a corner you don't just turn the handlebars and stay upright, you lean sideways a bit (without noticing) and turn the handlebars so the bike follows you so you don't fall off.

Rubbish explanation but maybe youll get something from it.

>> No.1757222

>>1757213
>I haven't bothered to read the troll thread.

If you think it's a troll thread, why are you replying? What the fuck is wrong with you?

>> No.1757231

>>1757213
If you'd read the thread, you'd have come across the link about countersteering, which explains how cyclists actually turn.

>> No.1757236

>>1756812
>But you can roll a quarter for quite a ways
totally different mass distributions

>> No.1757251

>>1757213
if this is a troll thread(legit discussion on balance), what is a non-troll one?