jumpr

When I consider the physics of riding a bike, it's amazing to me that we're actually able to keep a bicycle upright. It seems like it'd be impossible, especially given all the changing conditions that a bike ride usually has (gear shifting, speed shifting, inclines, etc.).

Do you think our brains and our inner ears somehow adapted to our environment to develop such fine motor coordination skills? I can't see how bike riding would be anything but an evolutionary development.

catatonic

nope, it's all cenfrifugal force from the rotating wheels. The wheels rotating provide a stabilizing force, that keeps up upright.

That's why the faster you go, the more you can lean into a corner.

Nightshade

Think horses. Horses & man are old as the dirt we walk on.

Maelstrom 

And THATS old

I don't think it comes naturally. I remember falling a lot when my dad showed me how to when I was short. I remember going to gearing and having to concentrate to shift until I got the hang of it. Everything about biking is progressing. You get to the point where it seems natural...but its learned, not innate. I know enough people who can't ride to know that.

skiahh

Gyroscopic force, actually, generated by the wheels' rotation. It's a pretty strong and stable force.

catatonic

I stand corrected. Yeah, it's just hitting enough speed for whatever wheelsize you have to provide enough force.

Kids have it rough since small wheels put out less gyroscopic force, so they have to go a bit faster to be as stable.

To prove that spin a 20" and a 29" wheel....which is harder to tilt once it's spinning?

BlazingPedals

I believe the gyroscope theory was thoroughly discredited years ago. What keeps a bike upright is the geometry. The exact relationship is rather complicated, but bikes have had over 100 years to get it right via trial and error. Rake, trail, and COG positioning all have an effect. A well-designed bike can be pushed riderless down a hill, and it will roll in a more or less straight line until it either hits something or slows below its stability speed. A rider doesn't balance the bike so much as UNbalance the bike to maneuver it.

Maelstrom 

I would believe this, I was considering mountain biking, at times my wheels are barely moving, but I am and the bike is being maneuvered. I really doubt there is any gyroscopic affect at those speeds. I am thinking really tight and technical riding like on the north shore where you are moving at a trackstanding pace.

chephy

Then how come this "geometry" doesn't keep it upright when the wheels aren't spinning?

catatonic

Maybe, but that would be a case of skill, since not everyone can balance on a bike moving at 2mph.

It's like Ballet, gymnastics, martial arts, pogo stick, etc....some can do it, but many cannot.

slvoid

It just cause humans are able to adapt pretty easily to different situations.
I don't think any human beings are hardwired naturally to place their hands at "ASDF" and "JKL:" either.

Maelstrom 

I hope not...considering I don't even know what the heck you are talking about I doubt it haha

catatonic

Look down mael...look down.

Maelstrom 

hahahaha...ok I get it. Sorry I flunked out of typing class. Due to some missing fingers I actually have hand placement at

as and ghjk

capejohn

As long as the bike is moving forward it will stay upright. It doesn't matter who or what is powering it. Don't give us humans credit we don't deserve.

unkchunk

I think it's the steering that keeps you up. When riding, gradualy slow down till you stop. At the moment you come to a complete stop you will start steering like crazy in an attempt to keep balance. Ride in the snow an you'll see that it's impossible to make a straight track. You are constantly steering the bike.

When you get down to it, it's merely complete Zen mastering of bicycle balance. If you had to conciously think about the necessary amount of handle bar angular rotation to correct balance, you could not do it.

Blackberry

So, let's say a bicycle was put in a time machine and sent back 1,000 or 10,000 years. I wonder how long it would be before someone put it on Ebay.

Trakhak

It is, as Unkchunk says, the steering; more specifically, it's constantly correcting to keep the bike under your center of gravity. You're using exactly the same technique of balancing and weight placement as you do when you walk and run. And it has little or nothing to do with frame geometry, either. For the purest demonstration of this, look at unicyclists. It's clear that gyroscopic force isn't at work when you're rolling the wheel back and forth under you to stay upright, much less frame geometry.

Coyote!

>>> it's constantly correcting to keep the bike under your center of gravity

Trak put the last piece in place, I believe. Try this on. . .I'm thinking we have this on-board processor that makes calculations for constant real-time corrections in balance, speed, and direction [vectoring]. The overall set of algoritha is the same one required for walking. Cycling uses the same vectoring process and ADAPTS it to two wheels versus two feet. It took time to adapt the process to walking. . .it takes time to adapt it to cycling.

Gyrostapo

The myth of gyroscopic forces keeping you upright is busted! (Scroll down on the linked page to see the totally rideable "zero-gyroscope bike").

operator

Just because you can't trackstand doesn't mean others can't.

catatonic

How is it then that a rider can stay up on rollers with only rotational forces, but not on bare ground with no rotational forces? Maybe they need to put one of these bikes on roller to test this. If they did, it would have been nice to see the paper on it.

Reason I still persist is that they gave no suitable conjecture as to what is actually doing the work. If they wish to truly rule out gyroscopic forces, then they should rule out as many variables as possible. In their experiment they pretty much left a big one, inertia. Rollers are great at removing any non-rotational inertia.

At least then we could see if it's actually the forward velocity that matters.

At this point I'm wanting to be convinced.

Hmm, maybe for fun deisgn rollers to provide the same effect as the bikes?

operator

Yes they can, thanks for playing though.

I have no clue where you're getting this idea.

catatonic

OK bad wording....with no rotational forces or velocity. You knew what I was talking about....now where is the rest of the info...what really IS keeping a bike upright then, and why can a person sty up on roller then?

Seriously...according to this experiment ALL bike riders should be capable of trackstnading, and we all know that's not true.

MadMan2k

I think you don't have to trackstand on rollers because the bike is still moving relative to the rollers under the wheel... if it was on flat ground holding still all that would happen when you steer is the front wheel would turn a little, but on rollers the front wheel turns and the whole bike starts to go that way, so it stays up. I don't think a bike would stay up on rollers if you just put a motor on the chainwheel to turn the back wheel - it would need the handlebar corrections to keep it upright.

Grab a bike and go out on flat ground, and put your right hand on the left grip. Try to keep it upright. It's crazy.
Not sure what it proves... maybe that we can make corrections to the bars without noticing if our hands are in the typical place, but if they're somewhere else we have to conciously make an effort of how to turn the bars, and it's harder to do as a result?