Talk:Rolling resistance

message: The definition of the "rolling resistance coefficient" refers to some "Figure 1", in which "F is the rolling resistance force". But in the Figure 1 (http://en.wikipedia.org/wiki/File:Rolling_Resistance_2.png) F is "some towing force applied to the axle". It is no clear if it is some force pulling the wheel that compensates the effect of the rolling resistance, of it is the force that provokes the wheel to loss energy and eventually stop.   — Preceding unsigned comment added by 186.135.53.190 (talk) 00:44, 11 October 2014 (UTC)
thread_title: Consistency between text and figures

message: :: I don't that thats right either, the smoother a surface, the lower the rolling resistance. Think about the difference between riding a bike on smooth concrete vs rough asphalt  - or even riding a bike on a bed mattress. The bed mattress would have the highest rolling resistance because its "squishy". Fresheneesz 20:17, 27 May 2006 (UTC)
replies: text: ...Right, the mattress has a high rolling resistance because it's squishy, not because its surface is rough. It doesn't matter how smooth it is for rolling resistance. Even if you put the smoothest silk sheets on that mattress, it would still be hard to ride your bike on it, because most of your energy goes into compressing the mattress and heating it up. —Keenan Pepper 21:07, 27 May 2006 (UTC)
thread_title: Additions

message: I'm going to change "g" in that equation to  F_N  for normal force. I think that would be more general. Fresheneesz 20:17, 27 May 2006 (UTC)
thread_title:  g vs normal force

message: That external link at the bottom is very interesting, is Crr's relationship with temperature not well documented? This would be something that should be on this page. Fresheneesz 23:05, 27 May 2006 (UTC)
thread_title: Temperature

message: The term 'slip', referred to road vehicles, is equivalent to 'creep' of railway wheels (see adhesion railway), it appears that automotive engineers don't talk to railway engineers. 
It is a misnomer because the region of contact is not subjected to actual sliding, but elastic distortion, the figure of 11% is indicative of the condition where the tyre forces arising from the shear stress in the region of contact are sufficient for gross slippage to occur.  Wheel forces arise from the elastic distortion of both the wheel and supporting surface at the region of contact.  
This cyclic distortion results in energy loss, particularly in materials which have high internal friction such as rubber, so rubber tyres on asphalt have higher rolling loss than iron tyres on steel rails, because the internal losses are higher, and a much larger volume of material is affected by the distortion.
There is some partial slippage at the edges of the region of contact, which adds further to the losses, but the region is effectively stationary, so that adhesion is governed by static friction, which is usually greater than sliding friction.  
I think what is meant in the article is the fundamental kinematic property of the wheel to transfer the motion of the vehicle relative to the surface from the region of contact to the hub, where greater control of the friction loss is achievable, hence roller bearings and lubrication.
Despite its superficial simplicity, the humble wheel is quite a sophisticated machine when studied to any depth.  Gordon Vigurs 10:46, 4 June 2006 (UTC)
thread_title: Definition of 'slip' 

message: This table does not cite an original source. If it is known where the values originated, please cite.
I was able to get a copy of the source for the passenger rail car coefficient, written by Astakhov. I'm entirely new to Wikipedia but I've uploaded it to the Wikipedia commons and allowing someone much more familiar with Wiki standards to include it in the references section.
https://commons.wikimedia.org/wiki/File:Pages_from_397774.pdf  — Preceding unsigned comment added by Ironchief (talk • contribs) 14:47, 21 November 2017 (UTC)
thread_title:  Table of Rolling Friction Coefficients 

message: From the formula given it seems that the rolling resistance is independent of the speed of the rolling object. Is that correct?--129.70.14.127 12:07, 11 May 2007 (UTC)
thread_title:  Rolling resistance independent of speed? 

message: Shouldn't this article be renamed to "Rolling friction".  That s what its called in physics.  Also the rename is needed to be consistent with Friction article. Firestonetireguy 17:22, 9 September 2007 (UTC)
replies: text: 'Opoose'Since it is mainly concerned with vehicles, rolling resistance is the usual term. Why not add a redirect if you want to cover both in the same article? Alternatively start a physics based page rather than an engineering one. Greglocock 23:09, 9 September 2007 (UTC)
thread_title: Rename to "Rolling friction"

message: The section "in braking" seems to me a tangent at best, more appropriate for an article on the physics of braking.  I think it should be at least moved later in the article if not moved to the brake article (which is rather thin at the moment).  Any thoughts?Ccrrccrr (talk) 03:50, 14 December 2007 (UTC)
thread_title:  "in braking" 

message: What sources do you have for the steel wheel/steel rail values?
I have found specific ranges in between 0.0002 and 0.0005 for c. 30" diameter wheels. That's 2e-4 to 5e-4, mainly from the following two sources:
-Gordon, David W. Bicycling Science. Cambridge, Mass. : MIT Press, c. 2004. (They computed a range of 0.0002-0.0005)
-Williams, John A. Engineering Tribology. New York : Cambridge University Press, 2005. (This one has a value of 0.0004, but doesn't specify a size but it strongly implies a regular-size railroad wheel)
It is my belief that the latter value in the first source, 0.0005, is often rounded to 0.001.
Just my two cents, hope it's correct.
:I finally fixed the problem by "pure rolling resistance".  The total rolling resistance is much higher (up to 0.0025).  I'll explain it, when I find time, in the article.  — Preceding unsigned comment added by 66.81.198.151 (talk) 02:54, 8 March 2012 (UTC)
thread_title:  Rolling resistance value for steel. 

message: ""Over inflating tires (such a bicycle tires) may not lower the overall rolling resistance as the tire may skip and hop over the road surface. Traction is sacrificed, and overall rolling friction may not be reduced as the wheel rotational speed changes and slippage increases.""
Reasonable men might conclude that if a tire is hopping and skipping, those moments would be marked with ZERO rolling resistance (yes, zero traction, as well--but this isn't a safety article now, is it?).  —Preceding unsigned comment added by 75.37.224.235 (talk) 16:29, 13 September 2009 (UTC)
replies: text: Yes, momentarily zero rolling resistances, but the energy loss when it hits after a hop could exceed the gain from zero RR during the flight.  Maybe some clarification needed, but I don't think there's an error.  --Ccrrccrr (talk) 19:44, 13 September 2009 (UTC)
replies: text: Yup, plus extra energy is pumped into any damping or shock absorbers in the suspension, the energy for which has to come from somewhere. I used to have a nice graph from Michelin showing this for our solar car.Greglocock (talk) 01:47, 14 September 2009 (UTC)
thread_title: Bicycle tire hopping due to inflation

message: I just added a picture illustrating the hysteresis effect. Further I would like add another picture showing plastic deformation (e.g. a wheel on soil, leaving behind permanent depression), if I can find the time. Besides that I would like to suggest some restructuring of the article. In my opinion we could do more to separate the different effects. Therefore the section "Rolling resistance can mean different things" could be moved up: directly after "primary causes"?  The section on physical formulas could be moved down?  It should be clearer about the phenomena that are incorporated here, instead of just quoting the external sources. Finally I suggest to remove sub-headers such as "Wheel bearing resistance", making slightly bigger paragraphs. Okay?
Edwinv1970 (talk) 15:45, 2 June 2012 (UTC)
thread_title: Suggestion for restructuring

message: Most of the work on rolling resistance is experimental and not theoretical, often resulting in empirical formulas.  Thus I think the topic of rolling resistance belongs to the "Transport engineering" wiki category and is part of the wiki project of "Civil engineering" both of which I've added to the talk page.  However, it started out under the physics heading.  Should it be removed from the Physics project?  I added a link to it from the "Railway engineering" article, which is just a bunch of links to other articles.  I think it's fine to continue to cover rolling resistance here for all types of vehicles since it facilitates comparisons. David S. Lawyer 00:38, 4 November 2013 (UTC)
thread_title: Should this article belong to Wiki projects: physics?, civil engineering?

message: Assuming "Coulomb's Law" is widespread, I suppose it is notable enough to be here. It does not, however, need to be scattered all over the article. Any mention of it should be prefaced by a note that it is incorrect.  — Preceding unsigned comment added by SllipsLacimech (talk • contribs) 21:13, 28 January 2014 (UTC)
thread_title:  Everything about "Coulomb's Law" should be in one section. 

message: http://indiatransportportal.com/wp-content/uploads/2016/02/india-rolling-resistance-itp-feb-2016.pdf is dead. I found something similar at https://www.slideshare.net/ArnaudRenard3/india-rolling-resistance-and-fuel-saving-2016 but I don't know whether it is the same and whether this is a canonical link.  — Preceding unsigned comment added by TN (talk • contribs) 12:21, 14 November 2017 (UTC)
thread_title:  Dead link 

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thread_title:  External links modified (January 2018) 

message: I cannot find support for these claims in the cited source:
:However, rolling resistance increases with increasing side deflection, for example while cornering or during the normal and constant precesssion associated with bicycle riding.  (Hence wider tires grip better while cornering.)  This precession is not present in vehicles having intrinsic lateral stability such as  automobiles.  The decreased rolling resistance due to increased tire cross-section diameter is more than offset by the increase in lateral rolling resistance due to the constant precessional motion in bicycling.  Hence, For bicycles (and less so for motorcycles) the total rolling resistance increases with increasing tire cross-section diameter.  Rolling resistance measurements made on bicycle tires using test equipment not taking into account natural lateral/precessing motion do not accurately measure the rolling resistance of bicycle tires.M. Guiggniani, "The science of vehicle dynamics: Handling, braking and ride of road and race cars" (Springer 2018)
Guiggniani doesn't seem to devote much space to rolling resistance or bicycles. Also, I am unfamiliar with this use of the word "precession", and I can't find where Guiggniani uses the word at all. -AndrewDressel (talk) 13:03, 23 May 2018 (UTC)
replies: text: My guess is that by precession he means camber change. Greglocock (talk) 22:54, 23 May 2018 (UTC)
replies: text: Yes, that is my guess also, maybe just the result of a poor translation, but it would be great to find the source that is making all these claims to be sure, and as far as I can tell, Guiggniani isn't it. -AndrewDressel (talk) 13:00, 24 May 2018 (UTC)
thread_title:  Rolling resistance in bicycle tires