Myth Of Gyro Precession in Bike Counter-Steering & Balance!

I always thought that bicycles were stable because the angle of the front fork and tire axle caused the bicycle to 'steer' itself under the center of mass (it's a self regulating system).

The article is very long and seems unecessarily complex. Isn't the basic reason a bicycle is stable fairly intuitive?

I don't think that's it, either, rosborne. It just won't stay upright long without a rider. They tell me it involves countersteering by the rider, but I didn't quite follow the discussion.

It seems obvious to me that a bicycle's tires create an upward, as well as horizontal force, when they spin simply by gripping the road if they are spinning fast enough. Thus, the maximum tilt angle should be governed by the speed that it is moving, and has nothing to do with gyroscopic action...

Keeping the topic to countersteering firstly, where I feel the most confusion and interest lies (pun):

I agree the article is abusively long and rambly (that why I summed it up with the actual zero Gyroscopic Bicycle as "proof" in my first post).

The essence of it is that the bikes they built clearly go against the popular notions of many, many people (lots of qualified educators etc) who will claim countersteering has to do with gyroscopic procession. Countersteering is not a function of gyroscopic procession!

Look up countersteering / gyroscopic procession / motorcycles and you guys will see what I mean! Yep even the "External links" on the main Wikipedia site on "Countersteering" are wrong as per gyroscopic procession & countersteering!

These are all links from the main Wikipedia site on "Countersteering", they are all full of Winnie the Poo as per gyroscopic procession & countersteering!

Gyroscopic effects
http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics#Gyroscopic_effects

Counter-Steering
http://www.msgroup.org/TIP048.html

Balancing Act
http://www.tonyfoale.com/Articles/Balance/BALANCE.htm

Countersteering
http://www.vsa.cape.com/~wayg/mrep/csteer.htm

I think it will. A biicycle going downhill without a rider will stay upright until it runs out of hill, or hits something. I don't know if that's called countersteering or not, but I never thought it had anything to do with gyroscopic motion.

When the center of mass of a bicycle moves to one side or the other, the front tire turns in that direction due to the way it is mounted. Turning in that direction causes the bicycle to drive back under the center of mass restoring balance. The faster the bicycle is moving the smaller the oscillations are.

Staying within the context of countersteering no that's not countersteering. Countersteering is pushing on the left bar and turning right, pushing on the right bar and turning left. Hope that helps.

As to whether a bike can stay upright without a rider at speed, I have seen lots of motorcycle races and sometimes the rider-less motorcycle shoots off in a straight line and sometimes the rider-less motorcycle sets up an oscillation and becomes a "tank slapper" then rider-less motorcycle falls at speed.

Outside the context of countersteering I can tell you this: the rake, the trial the wheel-base, and the center of gravity play a very large part in a bike's inherent (straight line) stability and race bikes (a.k.a. sport bikes) are purposefully unstable as compared to cruisers (a.k.a. Harley's).

http://www.bikeforums.net/showthread.php?t=190019&page=2&highlight=gyro

Dang it, I couldn't name my link!

Here, read the commentary by Dannoxyz

Sure! It fits well with my views on "the rake, the trial the wheel-base, and the center of gravity playing a very large part......" and he say it very nicely too!

But I disagree with Dannoxyz that in all cases "a bike is in perfect balance and harmony at speed and will ride by itself! After many motorcycle-wrecks on the track, you'll see that the motorcycle continues on in a perfectly straight line after it's thrown off the rider..." as per my observations of motorcycle racing and rider-less tank-slappers at speed.

PS: what he means by "headtube-angle" is rake.

And, I've heard (but not tried) that a bicycle on rollers (a training device) has no stability, regardless of how fast you spin the wheels.

Neat stuff and that Dannoxyz sure describes it very well (a lot better than I could!) Me thinks the biggest myth however lies (pun) with countersteering.


I note "skiahh" is still confused 'bout countersteering:

"Isn't countersteering a good example of the gyroscopic forces and precession at work on a bicycle or motorcycle? I know from experience that iIt's harder to initiate a turn at 100 MPH on a motorcycle than at 50."

Chumly, I don't know what you've read that you disagree with and I wasn't able to follow your link as it is no longer valid, but gyroscopic precession certainly does aid counter-steering and also aids balance.

Simply Google "First Zero Gyroscopic Bicycle". Bear in mind I will not likely respond to the logical fallacy of argumentum ad nauseam or the logical fallacy of argumentum ad populum. Read all my above posts carefully and in full.

Chumly,

Could you please explain how precession is related to balance? I think you are confusing the two.

Bikes stay upright without people on them just fine, if they are balanced to begin with.



Cycloptichorn

They aren't inherently stable--that's what gave the Wright's the advantage the invention of the airplane. The Wright's were bicycle mechanics and were aware that active control, like that of a bicycle, was necessary for flight control. Langley and Levinthal were trying to construct inherently stable airframes which were (and are) impossible. The Wright's experience here with the practicality of active control for an unstable craft lead them to the 'wing warping' solution.

On the other hand in the late 60's there was a research project to build an 'unrideable' bicycle to analyze what made the bicycle dynamically stable. Three were built --one with counter-rotating wheels to kill off gyroscopic effects--it was still rideable. The most unrideable had an extended lead on the front wheel with a standard rake. However it was still rideable.

Scientific American (I believe) published an article on the URB's (UnRideable Bicycles) in early 1970.

Rap

Nice Ghost Ride!

Just to be sure we're in phase with each-other, would you kindly quote where I said "precession is related to balance"?

Maybe the term "balance" in the title threw me off. Just to make it clear, we are talking about turning the bicycle, not keeping it upright, right?

Wats up faggots!!!