Thanks Vi, for the 8-turn video. Your concept looks really promising for a folding bike. As soon as I have some time I will weld a prototype to test it.
On 16.04.2011 07:40, Vi Vuong wrote: > Sorry, didn't copy/paste the last 3 characters > http://www.youtube.com/user/B100SaaThe finnish guy who made the videos is not known to us so far. The turning ability of his bike is amazing.
Cheers, Jürgen.
________________________________ From: Vi Vuong <vi_vuong@xxxxxxxxx> To: python@xxxxxxxxxxxxx Sent: Fri, April 15, 2011 10:32:55 PMSubject: [python] Re: A Bicycle Can Be Self-Stable Without Gyroscopic or Caster EffectsHi Pascal,Youtube user b100Saa has done some study on self-centering effect with various weights,http://www.youtube.com/user/B100 Maybe someone here knows him personally.Their model bike is most similar to low/midracer recumbent with fixed boom. On a python moving "boom", the weight on pivot would to be much greater than the BB assembly to self-steer. However, we can leave out the top-heavy BB to make it easy to illustrate the self-centering effect. I can build a miniature model small enough to roll down slope driveway if you are willing to start a python paper as a group effort. With realistic bike + rider, I think the subject of hands-free riding (freedom) is worth pursuing...Vi ________________________________ From: "pybuen@xxxxxxxxx" <pybuen@xxxxxxxxx> To: python@xxxxxxxxxxxxx Sent: Fri, April 15, 2011 7:01:28 AMSubject: [python] Re: A Bicycle Can Be Self-Stable Without Gyroscopic or Caster EffectsGood spotting, Christian, thanks for the news. One of the co-authors, A. L Schwab, usually provides his publications on his website (you are usually allowed to - depends on the journals though, not sure with Science). This one is brand new (from today), so it's not yet there, but might appear soon:http://bicycle.tudelft.nl/schwab/Publications/papers.htmOk, I just saw somebody posted a link with the article, so now you'll be able to grab it.Anyway, most of the material can prob. be found in other articles of his (recycling is common...) that you might also be interested in, I have recently commented on one of those a some weeks ago://www.freelists.org/post/python/Cool-handlebar-for-48deg-20in,16The videos on the link by Marek say it all anyway. I also agree with Jürgen's feel.Gyroscopic effect is known since the 70s to not contribute significantly to stability (Jones). Not so sure about the Caster effect for _riderless_ bike, that part may be new. Has anybody tried to launch their python at various speeds, e.g. down a hill? Maybe you would have been writing a "Science" paper if you had :) Note: load it up with sandsacks before trying...(self-centering effect). The riderless feature is just about control: the tendency of the bike is to recover from a potential fall by self-steering. Not sure how a Python bike would behave. Anyone to volunteer?Pascal On Fri, 15 Apr 2011, Jürgen Mages wrote:Thanks Christian. The clue is: if the rear part's center of gravity is shifted far enough over the front part, then the negative trail bike is inherently stable.Cheers, Jürgen. On 15.04.2011 12:11, Christian Andersen wrote:Hi folks In Science there is an article about bikes, that could be interesting for those of you guys, who have sufficient knowledge (unlike me). Maybe it is worth to have a look at to improve the pythonconcept regarding stability. http://www.sciencemag.org/content/332/6027/339.abstract Science 15 April 2011: Vol. 332 no. 6027 pp. 339-342 DOI: 10.1126/science.1201959 * Report A Bicycle Can Be Self-Stable Without Gyroscopic or Caster Effects1. J. D. G. Kooijman1, 2. J. P. Meijaard2, 3. Jim M. Papadopoulos3, 4. Andy Ruina4,*, and 5. A. L. Schwab1Abstract A riderless bicycle can automatically steer itself so as to recover from falls. The common view is that this self-steering is caused by gyroscopic precession of the front wheel, or by the wheel contact trailing like a caster behind the steer axis. We show that neither effect is necessary for self-stability. Using linearized stability calculations as a guide, we built a bicycle with extra counter-rotating wheels (canceling the wheel spin angular momentum) and with its front-wheel ground-contact forward of the steer axis (making the trailing distance negative). When laterally disturbed from rolling straight, this bicycle automatically recovers to upright travel. Our results show that various design variables, like the front mass location and the steer axis tilt, contribute to stability in complex interacting ways. greez, christian a wannabe pythonrider
============================================================ This is the Python Mailinglist //www.freelists.org/list/python Listmaster: Jürgen Mages jmages@xxxxxxTo unsubscribe send an empty mail to python-request@xxxxxxxxxxxxx
with 'unsubscribe' in the subject field. ============================================================
