Immagine
 Trilingual World Observatory: italiano, english, română. GLOBAL NEWS & more... di Redazione
   
 
\\ Home Page : Articolo
TU Delft casts aside some old theories. Why does a moving bicycle not fall over?
By Admin (from 04/07/2011 @ 08:00:59, in en - Science and Society, read 1126 times)

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.

 xhtmlc

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). A mathematical model with around 25 physical parameters was developed at the time, which appeared to be able to predict very accurately whether, and at what speeds, a particular design of bicycle would be stable.

The Experiment

'In our publication in Science we have now shown not only theoretically but also by means of experiment  that our insights are correct.' Together with PhD student Jodi Kooijman, Schwab designed and constructed a bicycle with which it could be shown, in an experiment, that both gyroscopic effects and trail are not necessary for a bicycle to remain stable by itself above a certain speed.
This is the so-called Two Mass Skate bicycle. It has small and counter rotating wheels, which means there is no gyroscopic effect to speak of, and a small negative trail (in other words, where the point of contact of the front wheel is marginally in front of the steering axis). And yet the bicycle remains stable.

See the experiment Here

Giving up

'It was not easy,' explains PhD student Jodi Kooijman, who carried out most of the experimental work. 'The first prototype did not work, and we had almost given up hope after a number of iteration attempts, when we suddenly found ourselves able to show the stability. But of course everything has to fall into place. You have to deal with the ground surface, for example, which has to have exactly the right roughness and stiffness. In Sporthal II of TU Delft we found all the right conditions.'

Steering

So the theory has now been proven by experiment. But has the experimental work led to the emergence of new theoretical insights? Dr Schwab answers, 'We have demonstrated that the mass distribution is also important for stability, especially the location of the centre of mass of the bicycle's steering mechanism.' For a bicycle to be stable, the steering mechanism has to be unstable; if the bike falls, the steering should fall even more quickly.

Bicycle manufacturers

Are the theoretical insights of Schwab and his companions of any use to bicycle manufacturers? 'Certainly. Today’s bicycles are the result of a fairly long evolutionary process, and are therefore rather conservative. Essentially, there is nothing about the basic design of the bicycle that has changed since the end of the nineteenth century. Manufacturers can use our model to make directed modifications to the stability of their bicycles. That may be of particular interest for unusual designs, such as recumbent bicycles, folding bicycles and cargo bicycles.'

Source: 3mE TU Delft

More information

Title: A Bicycle Can Be Self-Stable Without Gyroscopic or Caster Effects.

Authors: J.D.G. Kooijman; A. L. Schwab (TU Delft), J.P. Meijaard (University of Twente), J.M. Papadopoulos (University of Wisconsin–Stout), A. Ruina (Cornell University)

Website Science publication, with extensive background material, photos and video: http://bicycle.tudelft.nl/stablebicycle/

Website Bicycle Dynamics research: http://bicycle.tudelft.nl/schwab/Bicycle/index.htm

Articolo Articolo  Storico Storico Stampa Stampa  Share
Cannabis seeds, Autoflowering seeds, Greenhouse, Sweet Seeds, Dutch Passion
comments powered by Disqus
 
Nessun commento trovato. No comments found. Nici un comentariu găsit.

Anti-Spam: dial the numbers CAPTCHA
Text (max 5000 characters)
Nome - Name - Nume
Link ( OPTIONAL - visible on the site - NOT a must )


Disclaimer
Tuo commento sarŕ visibile dopo la moderazione. - Your comment will be visible after the moderation. - Comentariul tău va fi vizibil după moderare.
Ci sono 4285 persone collegate

< ottobre 2020 >
L
M
M
G
V
S
D
   
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
 
             

Titolo
en - Global Observatory (605)
en - Science and Society (594)
en - Video Alert (346)
it - Osservatorio Globale (503)
it - Scienze e Societa (555)
it - Video Alerta (132)
ro - Observator Global (399)
ro - Stiinta si Societate (467)
ro - TV Network (149)
z - Games Giochi Jocuri (68)

Catalogati per mese - Filed by month - Arhivate pe luni:

Gli interventi piů cliccati

Ultimi commenti - Last comments - Ultimele comentarii:
Hi, it's Nathan!Pretty much everyone is using voice search with their Siri/Google/Alexa to ask for services and products now, and next year, it'll be EVERYONE of your customers. Imagine what you are ...
15/01/2019 @ 17:58:25
By Nathan
Now Colorado is one love, I'm already packing suitcases;)
14/01/2018 @ 16:07:36
By Napasechnik
Nice read, I just passed this onto a friend who was doing some research on that. And he just bought me lunch since I found it for him smile So let me rephrase that Thank you for lunch! Whenever you ha...
21/11/2016 @ 09:41:39
By Anonimo


Titolo





29/10/2020 @ 09:59:10
script eseguito in 765 ms