Posted on 04/14/2011 3:46:45 PM PDT by decimon
Given sufficient forward speed, a bicycle pushed sideways, will not fall over. Scientists have been trying to find a conclusive explanation for this remarkable characteristic for over a century. This week, researchers at TU Delft have thrown new light on the question in a publication in Science.
Staying stable
The research at TU Delft, in collaboration with scientists from Cornell University (USA), centred on the following intriguing question: why is a bicycle self stable, above a certain speed? You add speed to a bike and can then give it a sideways push without it falling over.
Rotating wheels
Scientists have long been poring over this complicated question, even from as far back as the nineteenth century. Until recently, the consensus within the scientific community was that the stability was very closely related to two factors. First, the rotating wheels of the bicycle were supposed to provide stability through gyroscopic effects. Secondly, it was thought that the ‘trail’ played an important part. Trail is the distance by which the contact point of the front wheel trails behind the steering axis.
Predicting
The publication by TU Delft in Science puts paid to this old notion once and for all. 'We have known for years that the generally accepted explanation for the stability of the bicycle was too simple,' says researcher Dr Arend Schwab of the 3mE faculty at TU Delft. 'Gyroscopic effects and trail do help, but are not essential for stability.' Dr Schwab and a number of colleagues brought out a publication several years ago on the theory behind the stability of the bicycle (in 2007 in Proceedings of the Royal Society, doi:10.1098/rspa.2007.1857).
(Excerpt) Read more at tudelft.nl ...
The government will announce the results of the study as the basis for new legislation outlawing unicycles.
Build a perpetual motion machine!
Its wheels act like two gyroscopes, they couldn’t figure that one out?
I notice the article doesn’t really answer the question. I think though that the main reason the bike doesn’t fall over is because of the rider—not the bike.
It defies all laws of physics. ;D
Less so than you might think. When I was a young kid, we would routinely jump off of fairly fast moving bikes. (Yes, plenty of injuries resulted). But the cool thing was that the bikes kept going and going, and resisted attempts to knock them over. Kinda cool, like a Ghost Rider.
I guess they’ve never seen Eric Idle’s scenes in “European Vacation”.
Its wheels act like two gyroscopes, they couldn’t figure that one out?
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And since they were counter rotating a sideways force appled to both through the steering axis would be felt at 90 degrees in opposite directions... in a normal bicycle with a (slightly) leading fork the “force” of the turn is felt most at the leading edge of the contact patch... I don’t know how a bike with counter rotating gyros would “feel” to the rider but you wouldn’t have that normal resistance that brings the wheel/handlebar back to center ... in other words riding it would most likely be more difficult ,, much like driving a car with a bad alignment ,, no positive caster or (even worse) negative caster.. (sometimes referred to by mechanics as “self aligning torque”)
Caption: The Moment Speaker Boehner Lost His Balls.
It links the abstract and has a video.
BBC has something that might interest you or the other medics here. It’s called Interactive Body.
http://www.bbc.co.uk/science/humanbody/body/interactives/3djigsaw_02/
That’s easy — put down the kickstand and walk away.
Yup. I noticed the same thing. A truly self-serving but non-informative bunch of verbiage.
Yes, but even if he goes very, very slow on his bike, a good rider doesn’t fall over. My suspicion is that it’s a combination of the two. It’s hard, if not impossible, for a rider to balance on the bike when he’s not moving.
Definitely. I used to teach kids how to ride bike by pushing them as fast as I could, and telling them to keep pedaling, the balance would work itself out.
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