User talk:AndrewDressel

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Welcome!

Hello, AndrewDressel, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Questions, ask me on my talk page, or place {{helpme}} on your talk page and someone will show up shortly to answer your questions. Again, welcome! -SCEhard T 06:51, 30 May 2006 (UTC)[reply]

Images

A note on images: the JPEG format, which you’ve been using a lot, is not very well suited for line graphics. In mathematical terms, JPEG encodes local gradients in matrices, which is a good method in some cases (e. g. for photographs) but fails in general. See also Wikipedia:Preparing images for upload for more information on this. I’ll try to convert some of your images to the SVG format (which encodes geometrical shapes and has a number of significant advantages over raster formats like JPEG), but two are problematic:

For Image:BicycleEigenvalues.jpg, it would be easier to make the plot in SVG. If you made the plot in Matlab, try using this script to export to SVG.

- Hmmm. I can't get it to create an image that I can view. My browser doesn't need a plug-in to render SVG, does it? AndrewDressel 15:37, 30 July 2006 (UTC)[reply]

It depends. Most browsers do not have built-in support for SVG, the notable exceptions being Firefox, version 1.5 or newer, Opera, beginning with version 8, Safari, and, to some extent, recent versions of Amaya. If you are using Internet Exploder and can’t get Firefox, you can try Adobe’s SVG plugin. However, the best way to check whether an image will display well on Wikipedia is to use the same tool which is used here: librsvg, which includes a viewer for SVG files, rsvg-view, which shows almost exactly what an image will look like after upload. Recent Linux distributions should offer packages for librsvg and similar options are probably available for other popular Unix clones (e. g. MacOS X and the *BSDs), but I am unaware of a Windows port of the viewer (although the a port of the library itself is available). The second best way, imho, is to use Firefox. —xyzzy_n 16:08, 30 July 2006 (UTC)[reply]

…Neat! The dimensions were set a bit too low (the text is hard to read below 150% magnification), but since SVG is a vector format, zooming the image does not incur any loss of quality. —xyzzy_n 12:48, 31 July 2006 (UTC)[reply]

- Finally got it to work with Adobe’s SVG plugin. I think librsvg is a site that only a developer would love. So now the problem is that I don't appear to be able to scale the image. I created it to be the same size as the JPG image, on my machine at home. Now, here at the cafe, it is too small. Is that correct? Images in SVG format do not scale? That's not too handy. AndrewDressel 13:07, 31 July 2006 (UTC)[reply]

SVG images do scale, somewhat better than raster images. (For the former, all you have to do is an almost lossless coordinate transform; for the latter, you have to recompute the values of all pixels, and after that, there’s always a visible impact on quality.) I don’t know why the size is wrong. From skimming the script, I’d say that the output should have the size you set for the plot in Matlab. However, you could easily scale the image with Inkscape. —xyzzy_n 13:37, 31 July 2006 (UTC)[reply]

For Image:BikeModel.jpg, I’m not really sure what to do. If you can get the image like that in Matlab, the same method as before might work. Otherwise, try exporting it to PNG (a lossless raster graphics format that is somewhat better than JPEG for this kind of image).

- It is written as VRML from MATLAB and rendered by a plug-in: Cosmo Player. AndrewDressel 13:07, 31 July 2006 (UTC)[reply]

In general, neither Word nor Paint are good tools for image creation or editing.

- They work fine for me. Since Wikipedia serves up raster images anyway, I don't really see the benefit of uploading vector images, especially if it means I then cannot scale them as necessary. AndrewDressel 13:07, 31 July 2006 (UTC)[reply]

The benefit of vector images is that you can scale them as necessary, without loss of quality. ;) Another benefit is that if somebody needs to edit a Wikipedia image, that can be done with relative ease if the image is in a vector format, but not so easily if it’s a raster image. —xyzzy_n 13:37, 31 July 2006 (UTC)[reply]

For vector graphics, try Inkscape. For other things, try GIMP. —xyzzy_n 14:00, 29 July 2006 (UTC)[reply]

Oops, I forgot about Image:BikeModel.jpg earlier. I can try to make a screenshot of the VRML file in PNG format if you send me the VRML file (e. g. compressed and by e-mail). I would then send the screenshot to you so you could upload it.

-Sure, you can follow the links on my page to find my e-mail address. I don't see yours on your page. Once you create the PGN image, you could certainly upload it yourself. There's probably some rule against uploading the VRML to Wikipedia, right? -AndrewDressel 03:22, 8 August 2006 (UTC)[reply]

There’s an ‘e-mail mail this user’ link in the ‘toolbox’ to the left (if you use the default skin). It’s not as comfortable as just putting the address somewhere, but I’m already getting enough spam. I think you can also just upload the VRML file—as long as the licence is right. That’s fine and we could link to it from the article, although VRML on Wikipedia is quite rare. The only example I have found so far is Image:Tetrakis_hexahedron.wrl. —xyzzy_n 14:19, 8 August 2006 (UTC)[reply]

Okay, I'll work on getting you a file. -AndrewDressel 14:31, 8 August 2006 (UTC)[reply]

(By the way, you have checked with your employer regarding uploading all those images to Wikipedia, haven’t you?) —xyzzy_n 00:41, 5 August 2006 (UTC)[reply]

-Ha ha. Which employer would that be? -AndrewDressel 03:26, 8 August 2006 (UTC)[reply]

Cornell University, I assume from your website. Did you create those images as part of your work for Cornell? —xyzzy_n 14:19, 8 August 2006 (UTC)[reply]

-Interesting question. I've been on a leave of absense for two years and have continued to work on my thesis. So, I'm not there and they are not paying me. In any case, I paid for my copy of MATLAB myself, the JBike6 application is freely downloadable, and its end user license agreement mentions only copies, not its output. -AndrewDressel 14:31, 8 August 2006 (UTC)[reply]

I guess it’s OK, then. (For future reference, see the last section of s:GPL for useful information.) —xyzzy_n 15:07, 8 August 2006 (UTC)[reply]

Bicycle and motorcycle dynamics

I’ve tried to change the citations a bit, away from the style of the articles you named in the todo list. The problem with it is that it’s difficult to follow while reading the article—it’s hard to tell whether a given citation refers to a newspaper article or a published paper. Also, with the other style, there is no need to maintain a second list of the same sources in the references section.

In the process, I omitted some sources because I did not think they are really usable. Since the article is about physics, it’s probably a good idea to stick to published scientific works for all important points. On this topic, could you please check whether Hand’s thesis has been published anywhere?

Regarding citation templates in general, please remember always to select the right one for a purpose (e. g. {{cite web}} for websites, but {{cite journal}} for (published) papers, even if there is an electronic version available) and read the documentation for the templates (on the template pages or their talk pages) to know the parameters.

As for the misconceptions, I don’t think the section should remain in that form at all. If there is a different point of view on the issue, it should be explained properly in the article—even if it’s technically wrong. —xyzzy_n 17:49, 4 August 2006 (UTC)[reply]

Hi, thanks for your message. This seems to be quite a complex subject, I’m afraid I’m not really qualified to add anything to the article. Compared to this, bottom brackets are a lot easier to understand! LDHan 22:58, 9 March 2007 (UTC)[reply]

Bicycle/motorcycle physics

You are one serious bicycle/motorcycle physics dweeb! I fell in love with the concept of countersteering when I first encountered it in the Motorcycle Safety Foundation course. Spalding 16:44, 29 June 2006 (UTC) (Copied from his talk page)[reply]

Countersteering (Duplicate of Talk:Countersteering)

That the lean angle is very small or that the handlebars are turned far in the direction of the desired turn does not mean that the momentary countersteering necessary to initiate that lean can be skipped. -AndrewDressel 14:52, 3 October 2006 (UTC)[reply]

I'm a farily experienced (motor)bike rider, and at very low speed, say walking pace, you do not countersteer (or at least it's optional), even to lean. Dave 04:23, 28 October 2006 (UTC)[reply]

How then do you create the necessary lean? -AndrewDressel 03:13, 29 October 2006 (UTC)[reply]

At the lowest speeds, you don't lean. Dave 17:01, 29 October 2006 (UTC)[reply]

Then how does one counter the Centrifugal force? -AndrewDressel 19:54, 29 October 2006 (UTC)[reply]

I don't see why it needs countering - tyre sidewalls should surely take it, as far as I know there's no reason why resultant force on the bike need be vertical (with respect to the bike). Dave

The reason the resultant force (sum of all forces) needs to be vertical with respect to the the bike (exactly coincident with the plane defined by the two wheel contact points and the combined center of mass of the bike and rider) is to keep the bike from falling over. I don't know what you mean by "tyre sidewalls should surely take it." -AndrewDressel 22:01, 29 October 2006 (UTC)[reply]

On reflection, as counter intuitive as it seems you must be right, as I can't see any other way there wouldn't be a resultant moment around the centre of mass. Dave 13:34, 30 October 2006 (UTC)[reply]

Reply to your inquiry regarding torque reaction in Talk:V-twin

I posted a reply to your inquiry. If you'd like to discuss, I'll check back there but I'm only on once or twice a week or so, so don't expect any heated discussions. ;) Un focused 03:28, 1 November 2006 (UTC)[reply]

Excellent, thanks. In fact, I pasted your entire 3rd paragraph into the article. I hope you don't mind. I actually have a Guzzi, and while I can notice when stopped at a light, it hasn't been a factor for me while riding. Perhaps I'm too casual. -AndrewDressel 19:54, 1 November 2006 (UTC)[reply]

Re: Gregarious Lonewolf's talk page

You wrote in the edit summary: (Fix typo: Those -> Though (hope you don't mind))

Thank you! No, I didn't mind it at all. :) Gregarious Lonewolf 20:08, 3 November 2006 (UTC)[reply]

Re: "a thread pitch unique to bike pedals."

Andrew: My error, unintended, was perhaps one of wording clarity, not technical accuracy. It is the "size & thread pitch" combination which is unique to bike pedals, see http://www.sizes.com/tools/thread_american.htm , as one of many examples, inc;luding your one Sears marketed tap & die set.

The SAE standard fine thread pitch for bolt size 9/16" is 18 TPI, not 20 TPI. No major bolt/nut, tap/die, or thread repair device manufacturer (including any custom product manufacturer I could find) in the U.S. or abroad, offers any products in a 9/16" x 20 TPI combination, even in only a RH tread. After a rather extensive Google search (broadband connection), Park (previously unknown to me) was the only manufacturer I could find which offered any 9/16" x 20 TPI taps, RH & LH threads (which I ordered from the lowest cost net retailer I could find); they do not offer dies in this size.

TPI is an individual characteristic; the reason TPI gauges are routinely supplied in better quality tap and die sets. As with all fastening systems, it is combinations of characteristics which come to be recognized as standards, not individual characteristics. My comment about the "9/16 in. x 20 TPI" combination being quite unique to bicycle pedals is factually correct, an apparent historical but accepted event in the history of bicycle part manufacturers, assemblers and retailers. "9/16 in. x 20 TPI" is neither a United States (SAE: Society of Automotive Engineers, sae.org usually the dominant authority) or a metric standard. Given current practice to manufacture bicycle cranks from aluminum, the 20 TPI standard, as opposed to the national course "9/16 in. x 12 TPI" standard, which provides a much deeper thread, renders bicycle pedal bolts more prone to stripping out the finer/shallower 20 TPI treads within bicycle cranks. It is also the reason many local bicycle shops either carry specialized repair kits for bicycle cranks (generally rated as of poor reliability by many in the bicycle business) and/or sell crank replacements.

The above issues are part of the reason I ended up doing a search on the "9/16 in. x 20 TPI" engineering odyssey. Having extensive mechanical engineering experience and some small scale manufacturing capability, I elected to purchase the Park taps and will manufacture my own steel inserts from center-drilled grade 8 bolts and in-turn drill, tap and epoxy these custome inserts into cranks needing repair. This should end up more reliable than most currently available cranks, in terms of pedal thread toughness.

As such, and for the benefit of others, I would suggest that you correct, rather than delete the comment about "9/16 in. x 20 TPI" being unique to bicycle pedals. Thank you. MA | T@lk 14:56, 26 November 2006 (UTC)[reply]

I believe that you will find that 20 TPI is an old BS Cycle Thread Coarse measurement. I'm well experience in "odd" threads as a Norton and Soviet bike owner. I believe that Bicycle Tap and Die sets are still manufactured in Russia and other parts of the FSU and you should be able to find those dies. M-72 07:38, 19 December 2006 (UTC)[reply]

bicycle and bicycle gearing

You've done a great job on moving stuff between these articles. Murray Langton 08:59, 30 November 2006 (UTC)[reply]

Motorcycle Forks

You are welcome for the photographs! I am glad you find them useful. -Jeff dean 23:21, 9 December 2006 (UTC)[reply]

I don't know who the mysterious M-72 is, but I appreciated and learned form his additions to your motorcycle forks page. He should make himself known! -Jeff dean 15:10, 10 December 2006 (UTC)[reply]

I know what you mean. Isn't it fascinating what information comes out of the woodwork? -AndrewDressel 15:53, 10 December 2006 (UTC)[reply]

Coaxial steering front suspension

But ... what does it LOOK like?? :) -Jeff dean 18:20, 15 December 2006 (UTC)[reply]

Hard to tell exactly. Plus, any image I can find certainly is copyrighted. Anyway, you can find some pictures here [1] that do not reveal much. Good luck. -AndrewDressel 21:04, 15 December 2006 (UTC)[reply]

Motorcycling Wikiproject

Welcome to the Motorcycling WikiProject. Hopefully you have a good time, start many new articles and can contribute lots to the existing ones as we need that. Cheers ww2censor 03:46, 24 January 2007 (UTC)[reply]

You've been doing some good work on the Motorcycling WikiProject, IMO. Just wanted to say "Thanks!" --Pi3832 12:59, 16 March 2007 (UTC)[reply]

Mountain Biking on Mount Tamalpais

Hello, An article that I created as a part of Wikiproject Cycling called Mountain Biking on Mount Tamalpais and linked to the Mount Tamalpais article, has been listed for deletion. If you are interested in the deletion discussion, please participate by adding your comments at Wikipedia:Articles for deletion/Mountain Biking on Mount Tamalpais. Thank you, Bob in Las Vegas - uriel8 (talk) 11:26, 17 February 2007 (UTC)[reply]

Talk Page Etiquette and a Request

Hey there, I figured you already knew this but I thought I'd give you a quick reminder. Regarding your edit here diff to the talk page at Mountain Bike. While moving the discussion was beneficial, generally correcting typo's and spelling mistakes of another user's post, even unsigned-in users, is frowned upon. People tend to view it as an insult. That said, i'd appreciate your help citing some sources at Cross-country cycling which is undersouced. Goodnightmush 16:25, 21 February 2007 (UTC)[reply]

Bicycle

Hello Andrew, I have taken a look at the most recent references you added to the article bicycle. The are excellent references for much of the material. Unfortunatelly, I coudn't find, out of the 3 links, anything that mentions "carbon fiber" is the most popular non-metalic frame. Of course it is an "increasingly popular frame material"[2]. I will change the word "primary" to "popular." Perhaps, you could also place your references at various appropriate locations throughout the paragraph since having them all at the begining doesn't seem as relevant. Thank you! --CyclePat 17:11, 13 March 2007 (UTC)[reply]

In response to your message on my user page. Please take note that there is strict policy regarding inclusion of material. Wikipedia articles must be based on reliable sources. Instead of trying to find counter exemples to this rule you may wish to try improve the sections of the article which you highlighted as lacking proper citations. --CyclePat 06:02, 15 March 2007 (UTC)[reply]

Welcome!

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Swords

Crossing swords with M-72, eh? I have given up on that. May the force be with you. Good luck! Jeff dean 14:37, 4 April 2007 (UTC)[reply]

Just trying to go about my day and make a positive contribution if I can. -AndrewDressel 16:39, 4 April 2007 (UTC)[reply]

Handlebar help

Perhaps you can help me out. Not with M-72, but with getting the facts straight about motorcycle handlebars. I got into it because I've been working on the handlebar article which I believe the motorcycle article links to. I thought it would be simple to say that motorcycle handlebars attach to motorcycle forks, but perhaps not (see the unsuing discussion). I'll appreciate any input you can provide. -AndrewDressel 22:07, 4 April 2007 (UTC)[reply]

Don't know how helpful I can be. I put together this PDF to sort out what feeble thoughts I have — http://jeff.dean.home.att.net/Triple-clamps.pdf

Clearly, the foot bone is connected to the knee bone ... etc. The handlebars are mounted to the triple clamp that, in turn, holds the top of the fork tubes.

In the case of the R1150RT, the handlebars actually are in two parts, and without the triple clamp they would fall apart. Both the RT and the GS are Telelever bikes, and both have triple clamps.

So the triple clamp appears to be the nexus that holds the whole front end together. The fork tubes are connected to the triple clamp, the triple clamp is connected to the head, the triple clamp carries the handlebar risers, the risers hold the bars (except here for the RT). You can almost sing it!

So the handlebars attach to the triple clamp (perhaps through risers, perhaps not) that, in turn, connects to the fork tubes.

Is that useful to you? Jeff dean 00:28, 5 April 2007 (UTC)[reply]

Yes, it is. Thanks. Hope my additions stick this time. -AndrewDressel 04:27, 7 April 2007 (UTC)[reply]

I put the R50/2 photo on Wikipedia and inserted it in Motorcycle fork. If you want other photos uploaded, let me know. Jeff dean 04:15, 5 April 2007 (UTC)[reply]

I see the Brewers lost one :( • By the way, might John Erdmann at BMW Motorcycles of Milwaukee be your dealer? Jeff dean 15:15, 5 April 2007 (UTC)[reply]

Nope. Bought the bike back east. Haven't been to a dealer out here yes. -AndrewDressel 04:27, 7 April 2007 (UTC)[reply]

Bicycle and motorcycle dynamics

I really like where the page is right now. I've seen it before where people had emphasized gyroscopic effect as the reason bikes are stable. The intro, "Experimentation and mathematical analysis have shown that a bike stays upright when it is steered to keep its center of mass over its wheels" is perfect, and the statement "the role of the gyroscopic effect in most bike designs is to help steer the front wheel into the direction of a lean" is a better explanation of gyroscopic effect. I'll likely restore my comparison to pogo sticks and ice-skating on one leg (which somebody removed) because they seem like perfect analogs to bike riding, yet there clearly is no gyroscopic effect. Your thoughts? Gekritzl

F.Y.I. → Citizendium

Because of the incredible amount of vandalism and the prevalence of anonymous users on Wikipedia, I am devoting more of my attention to the new, more controlled competitor, Citizendium, and less to Wikipedia.

It is not certain that Citizendium will survive and prosper, but I think it is worth the support of honest users of Wikipedia. If it does prosper, I will likely work with it exclusively in the future.

Jeff dean 17:31, 16 April 2007 (UTC)[reply]

Bicycle brake systems

Yeah I agree, there really wasn't much point in those edits, just mostly minor rewording. I just corrected a couple of errors, but the section on sidepull and centrepull brakes are not very well written and could do with some improvements. What's really need is a pic of a centrepull brake, but unfortunately none of my bikes have them. LDHan 21:50, 26 April 2007 (UTC)[reply]

Bicycle and motorcycle dynamics again

Hi. Was just going through assessments for cycling articles when I came across this article. I think it's really good - but I'm no expert :). I was thinking of nominating for Good Article status as a stepping stone to FA. Do you have the time to be able to help if and when improvements are suggested? My knowledge of this subject is limited to the article! I think this could be the first recognized cycling Featured Article in a fairly short time. Severo^TC 22:37, 8 May 2007 (UTC)[reply]

Nice one! I thought it would need the formal procedure again and was going to copyedit tomorrow (when I have some time to do so!) and re-nom, but nevertheless, great work, thanks! Severo^TC 20:02, 14 February 2008 (UTC)[reply]

Recent change to Bottom bracket article

Sorry, my mistake, I thought I was removing "THERE ARE IN 68 ,70, 73 mm.". I opened the edit page to make the change and by the time I saved it you had already done it, it's now fixed. LDHan 19:01, 12 May 2007 (UTC)[reply]

Welcome to VandalProof!

Thank you for your interest in VandalProof, AndrewDressel! You have now been added to the list of authorized users, so if you haven't already, simply download and install VandalProof from our main page. If you have any questions, please feel free to contact me or any other moderator, or you can post a message on the discussion page. Daniel 04:53, 18 May 2007 (UTC)[reply]

handlebar → bicycle handlebar

Hello, AndrewDressel. It appears that you copied and pasted handlebar to bicycle handlebar. Please do not move articles by copying and pasting them because it splits the article's history, which is needed for attribution and is helpful in many other ways. If there is an article that you cannot move yourself using the move link at the top of the page, follow the instructions at Wikipedia:Requested moves. Also, if there are any other articles that you copied and pasted, even if it was a long time ago, please list them at Wikipedia:Cut and paste move repair holding pen. Thank you, Christopherlin 03:31, 13 June 2007 (UTC) (Cool, there's a template for this!)[reply]

Cranks vs crank arms

Yeah I know "crank arm/crankarm" is commonly used by cyclists and the cycle industry, but "crank" is not a short name and is the correct technical term, Jobst Brandt has written about this. Perhaps one or two sentences could be added to explain this. LDHan 00:18, 7 July 2007 (UTC)[reply]

http://yarchive.net/bike/jargon.html http://groups.google.co.uk/group/rec.bicycles.tech/browse_thread/thread/1d36f3bec8c44c94/85e2a50c4d09c205?q=Straightening+a+bent+Dura+Ace+crank+arm&lnk=ol&hl=en&# http://groups.google.co.uk/group/rec.bicycles.misc/browse_thread/thread/c277f1a7ba1e62a3/61bbce25c1e72b19?lnk=st&q=help+bicycle+terminology&rnum=5&hl=en#61bbce25c1e72b19 I'm not too bothered whether if "crank" or "crankarm" is used in the article. LDHan 13:43, 13 July 2007 (UTC)[reply]

Sociable

I have just created a new article on the Sociable. Would you like to contribute? Jason7825 22:54, 31 July 2007 (UTC)[reply]

Wheelbase

Hi, Andrew. I've added a question on Talk:Bicycle and motorcycle dynamics. You seem to be an authority on the subject. Regards, LarRan 14:18, 1 September 2007 (UTC)[reply]

Merger proposed: Twinshock → Suspension (motorcycle)

It has been proposed to merge the content of Twinshock into Suspension (motorcycle). Since you have previously edited one of these articles, I thought you might be interested. You're welcome to participate in the discussion if you like. --B. Wolterding 15:51, 14 September 2007 (UTC)[reply]

Freewheeling Crankset Article

I certainly thought that the article made it clear that it was indeed a solutions in search of a problem. The system had several bugs including weight and safety, and in any case, was poorly implemented as well. As far as industry authority, I remember Sheldon Brown calling the system impractical, but he may or may not be considered "industry". I try to contribute where I can, but I often wonder why. Linns 02:21, 28 September 2007 (UTC)[reply]

Well, I understand that the article is a stub – but that doesn't mean it shouldn't be factually accurate, right? At any rate, Sheldon Brown refers to the FFS in his glossary (http://www.sheldonbrown.com/gloss_e-f.html#ffs) as "a solution in search of a problem". Shall I add him as a source, or do you wish to? Linns 02:39, 29 September 2007 (UTC)[reply]

Steering Discussion

Hi Andrew, I feel our recent discussion on the Talk:Bicycle and motorcycle dynamics page is getting a little lengthy and I have decided not to add any more on that thread for a while.

Thank you for your responses. They have given me new angles for which to prepare research and have convinced me that other mechanics besides countersteering are available and used in different situations of steering a bike. Yes, yes, I must provide reference. I'll do my best.

P.S. Regarding human and other mammalian body mechanics, explore how it is described by the Alexander Technique. Beware of some of the practitioners/websites, though, they may make it seem like some sort of magic. It is based in part on inhibiting the startle reflex and that "the head leads the body into action" and has been scientifically proven as a discovery and not an invention. I have lost the reference, much professional apologies.

-Until later, Earth to McFly (talk) 17:21, 28 November 2007 (UTC)[reply]

I posted a short response on my talk page – to your post on my talk page. Earth to McFly (talk) 16:10, 29 November 2007 (UTC)[reply]

Changes to Bicycle & Bicycle Performance

I don't quite understand what the problem was. Drag is quadratic in speed, so it increases linearly with speed. Power is cubic in the speed, so it would increase quadratically. The source says that the drag is $\rho AV^{2}$ , so when one speaks of the drag's increase with speed, not the drag itself, why is it not the derivative of that expression, i.e. the drag increases linearly with speed? Besselfunctions (talk) 20:26, 26 December 2007 (UTC)[reply]

Ah, now I see. It appears to be just an issue of semantics, not mathematics. You are interpreting "is quadratic in" to be equivalent to "increases linearly with". However, the cited source, in discussing air drag explains that "the force exerted by the drag is seen to increase as the square of the velocity." The author does not use the derivative of the derived expression to describe how a change in velocity translates into a change in drag. Instead, he uses the original, quadratic relationship. For example: doubling speed results in a four fold increase in drag, even though the derivative of the drag with respect to velocity is proportional to the velocity and not its square. -AndrewDressel (talk) 20:55, 26 December 2007 (UTC)[reply]

Chicken strips

OK doke. --Woohookitty^Woohoo! 17:31, 2 February 2008 (UTC)[reply]

Bicycle and Motorcycle Dynamics

Yeah, no worries. I know how hard to swallow a delist can be, and how long articles can sit once nominated. Some editors doing sweeps put articles "on hold" for a week to see if improvements happen—I've found that rare enough that it's easier to delist and relist if necessary. Thanks again for you prompt, hard work after my comments! --jwanders^Talk 20:25, 14 February 2008 (UTC)[reply]

You're Welcome

I fix typos wherever I can, glad you appreciate it. My time at RPI has been a great few years. Thanks for the note on my links, all better. It's incredible that you helped found MapInfo. The Formula SAE team actually uses the parking lot behind the headquarters for trial runs and tuning. Also of note is the Formula Hybrid team which was recently founded. Next time you're in Troy, stop by either shop. The teams could probably benefit from your experience with bike/motorcycle dynamics. Lombar2 (talk) 07:44, 26 March 2008 (UTC)[reply]

Cyclocomputer sensor caption

Hi! ~~This may sound really trivial and petty~~... scratch "may sound", it is really trivial and petty, but...
The caption for Image:Cyclocomputer_sensor.JPG reads "A wired Hall effect sensor with spoke mounted magnet." Me, I'd much rather have computer which works by interesting Hall effect than by a boring old reed switch. Tesla and Edison pretty much irrelevant to this, but as famous engineers go, who's the more interesting?
Naturally enough, instead of looking for reliable, verifiable and peer-reviewed reference info, I did some good old fashioned Original Research. The sensor in the pic is the sensor unit for a Cateye cyclocomputer. Got similar Cateye sensors on my bikes. Waved a fridge magnet at them (sensors, not the bicycles) and could hear a teeny "pink, pink, pink" of what I guess is a reed switch, as the cadence read-out displayed 199.99 and my maximum trip speed went up from 35kmh to 92kmh.
Admittedly, my sensor kits (like my bikes, and myself) are all pretty ancient. Going by the forks' paintwork, the forks (Reynolds tubing? Columbus?) and their dropout pattern, and the QR skewer's cam lever and retaining nut, the bike in the pic looks like an oldie-but-goodie. The sensor unit looks newer. However, I don't think Cateye would have more latterly changed from reed switch to Hall effect sensors - Hall effect sensors apparently have magnitudes larger current drain on head unit batteries. Do you think the pic caption should be altered?
--Shirt58 (talk) 11:34, 26 March 2008 (UTC)[reply]
ps: Is that an old Avocet hub-mounted sensor magnet in the pic? Now, they used Hall effect - and this comment may be even more completely wrong-headed than it is already...

Free body diagram

Hi. I ran into Image:Free_Body_Diagram.png this evening and I was wondering what software you used to generate it. I have occasionally wanted to draw diagrammatic stuff and gotten stuck somewhere between Paint (too little) and Illustrator (often too much). Thanks in advance for whatever tips you can offer. --Dvortygirl (talk) 02:38, 20 May 2008 (UTC)[reply]

Re: Bicycle tool kits and French chalk

Specifically this bit At the least this will include a tire patch kit (these contain tube-patching material, an adhesive, a block of French chalk and a metal grater to reduce the chalk to powder

I've seen this around so they're available at least in the UK, no idea what merits the inclusion of "Many" cyclists carrying them however. Severo^TC 14:29, 23 May 2008 (UTC)[reply]

I can't verify "to reduce the chalk to powder". I was going to offer to take a picture of a kit I have in the other room with a metal grater and chalk, but the chalk has gone missing! Severo^TC 10:18, 29 May 2008 (UTC)[reply]

Your source is wrong, also needs better reference, half true! —Preceding unsigned comment added by Indwisdom (talk • contribs) 20:25, 28 May 2008 (UTC)[reply]

Edits to Bicycle

Hi Andrew—That's really strange. Actually, the edit was to remove the piping in the wikilink, which is always done. But I removed the grater --> greater edit, as you pointed out. Why AWB got the two mixed up, I have no idea. Perhaps I should stop allowing AWB to provide the Edit Summary. Do you know if it commonly makes ES mistakes like this? In any case, thanks for bringing this to my attention. --AnnaFrance (talk) 15:29, 26 May 2008 (UTC)[reply]

Bicycle and motorcycle dynamics

Looks like a fascinating article, but I see from the talk page that the WP:GA group thinks it needs a copy-edit, that it doesn't follow WP:MOS guidelines. I'd be delighted to see if I can help with this effort. I think I could get started tomorrow. Thanks for letting me join the group. --AnnaFrance (talk) 17:17, 26 May 2008 (UTC)[reply]

Bicycle and motorcycle dynamics talk page archive

I left you a message on the talk page today about the Instability section, and that I was going to try my hand at archiving the talk page late tonight. I have just done that, and it appears to have worked just fine. If you didn't see my message earlier, this will give you a chance to check out the archive, which is where that message is now. --AnnaFrance (talk) 04:36, 1 June 2008 (UTC)[reply]

Image:Free Body Diagram.png

Do you have the source to your diagram Image:Free Body Diagram.png? It needs to be modified, since it shows the frictional force going through its true line of action but the normal reaction going through the block's centroid, which is not, which is somewhat misleading. Thanks, BigBlueFish (talk) 16:08, 9 June 2008 (UTC)[reply]

Not handy. I just drew it in MS Word, then pasted it into Paint to save it in PNG format. To where do you propose to move the normal force arrow? Its exact location is not known without additional information and further analysis. -AndrewDressel (talk) 16:26, 9 June 2008 (UTC)[reply]

I may stand to be corrected, but since the weight acts through the surface of contact, the normal reaction must act through the point on that surface vertically below the centre of mass, or there would be a net rotational acceleration. BigBlueFish (talk) 16:39, 9 June 2008 (UTC)[reply]

That would eliminate any moment due to the gravitational and the normal forces if they were in opposite directions, which they are not, and would not address the moment generated by the friction force. All of this only applies to the static case, which is not given. In fact, if the coefficient of friction is zero, then the normal force is correct as drawn. Otherwise, the acceleration must be known in order to correctly place the single, resultant normal force arrow. -AndrewDressel (talk) 16:50, 9 June 2008 (UTC)[reply]

If their lines of action intersect then there is no moment regardless of direction. BigBlueFish (talk) 17:06, 9 June 2008 (UTC)[reply]

This contradicts your statement above. Since the normal force is not parallel to the gravitational force, their lines of action will always intersect somewhere, no mater where the normal force is applied. That would mean that the normal force and the gravitational force could never create a moment, which is not true. -AndrewDressel (talk) 19:44, 9 June 2008 (UTC)[reply]

The normal and gravitational forces only produce a moment if the weight acts outside the surface of contact. Within this boundary the forces must cross on the surface or the frictional force exerts a moment with the other two. BigBlueFish (talk) 20:57, 9 June 2008 (UTC)[reply]

Yes, for a three-force member in static equilibrium. However, there is nothing about the diagram or the article that states that the block is not moving. -AndrewDressel (talk) 01:02, 10 June 2008 (UTC)[reply]

Even in a dynamic case the block has no angular acceleration, and all acceleration occurs in a plane perpendicular to the normal reaction, so it is not affected. BigBlueFish (talk) 17:06, 9 June 2008 (UTC)[reply]

No angular acceleration is necessary for angular momentum to be a factor. A braking car will experience "weight shift" to the front wheels even if the suspension and the wheels are rigid. No rotation is necessary for this to occur. -AndrewDressel (talk) 19:44, 9 June 2008 (UTC)[reply]

Forgive me if I find this a little hand-wavey. I'm not aware of any case in which the vertical force on the wheels of a braking car is imbalanced, or indeed there would be a net moment on the car. A truly rigid car has no angular momentum because its path has an infinite radius of curvature. BigBlueFish (talk) 20:57, 9 June 2008 (UTC)[reply]

No hand-waving necessary. It follows directly from the definition of angular momentum about a point, H_p = r_/p x mv, and the correct application of angular momentum balance. You may read about it in the Bicycle and motorcycle dynamics article. The citation includes a link to a PDF copy of a statics and dynamics textbook published by Oxford University Press. -AndrewDressel (talk) 01:02, 10 June 2008 (UTC)[reply]

Besides whatever effect or phenomenon you're trying to describe, the simple case that the diagram is trying to describe either shows a block in mechanical equilibrium on a plane or a block sliding down it, both of which are cases in which the free body illustrated experiences no net moment. BigBlueFish (talk) 20:57, 9 June 2008 (UTC)[reply]

There is no net moment only in the static (or constant velocity) case. If there is acceleration, then the net moment about any point must equal the cross product of the position vector from that point to the center of mass with the product of mass and acceleration vector of the center of mass:M_p = r_cm/p x ma_cm. Using a point that coincides with the center of mass provides no information, of course, because the position vector has zero length: the net moment about the center of mass is zero.

As for what I am showing in that diagram, it happens to coincide with option c of the three "sensible" ways to represent contact force distributions shown on page 95 of the same textbook mentioned above. One more option I've seen in a different text that is slightly more complicated is to indicate an unknown distance "d" from one edge to the point of application. -AndrewDressel (talk) 01:02, 10 June 2008 (UTC)[reply]

Bicycle and motorcycle dynamics images

Wow. That's bizarre. How could text and images get mixed up in a table? IE must be unusual, because we tested with several browsers on Macs and PCs, to make sure everything looked just right. Anyway, so the images are in bad shape as they stand now. I guess you'd better fix them. --AnnaFrance (talk) 02:30, 17 June 2008 (UTC)[reply]

Dangerous old books

I recently acquired a reprint of one of the coolest old books and was reading some of it today. I like to read it, it doesn't make me want to change my gender but it helps me to enjoy the other (I am old school, and think that there are only two of these...). One of the chapters might contain information that would be good for a balloon article -- I am not familiar with the structure of those articles here enough to add it though. Here is as beautiful of a citation filled out that I can make for it:

Beard, Daniel Carter (1890). "Chapter XV: Fourth of July Balloons with New and Novel Attachments". [[The American Boy's Handy Book]]. Retrieved 2008-06-26. {{cite book}}: External link in |chapterurl= (help); URL–wikilink conflict (help); Unknown parameter |chapterurl= ignored (|chapter-url= suggested) (help)

If you already knew of this, forgive me for the redundancy. -- carol (talk) 04:40, 26 June 2008 (UTC)[reply]

Eigenvalues

Hi Andrew,

I'm unfamiliar with the conventions for contributing to Wikipedia, so forgive me if my note to you is inappropriate. I just put the following comment in the "Talk" section for "Bicycle and motorcycle dynamics". Since you seem to be very active on bicycle related articles, I thought I would ask you directly. I'm very puzzled about the "Eigenvalues" section:

It appears to me that the capsize speed and the weave speed are reversed, both in the text, in the eigenvalue plot and in the PDF reference [17] by Meijaard, et al. My own experience is that at low speed a bicycle will "capsize" (fall over without any weaves), while at high speed on a poorly designed bicycle the weaves can increase in amplitude until "failure". I'm not an expert, nor a prior contributer to Wikipedia, so I hesitate to make any changes. Maybe the text is simply very confusing and in need of editing (if so, I could easily manage that!).

I guess it is not standard practice to give email addresses, but I don't mind giving mine: srwenner@verizon.net. —Preceding unsigned comment added by 70.19.219.159 (talk) 23:09, 13 July 2008 (UTC)[reply]

The text currently glosses over a mode that perhaps matches what you describe. Before the two most positive eigenvalues coalesce into a complex conjugate pair, which indicates oscillation, they indicate simply falling instead, as an inverted pendulum. It is only when the complex components show up, at about 1 m/s, that the weave oscillation begins. Perhaps that better matches your experience. You or I should add that detail. -AndrewDressel (talk) 23:38, 13 July 2008 (UTC)[reply]

Countersteering

Yes, a fascinating discussion. I feel like I'm always on the edge of totally understanding the topic, but never quite there. I guess it's a bit like balancing a bike... This article and your comments have been very illuminating for me. By the way I just added a Countersteering#Bicycles section which hopefully you agree complements the existing Motorcycles section that now follows it. --Serge (talk) 19:06, 7 August 2008 (UTC)[reply]

Cogset article

Hi, I see you've been editing the cogset article, and seem to be active on wikipedia and very knowledgeable about bikes. I think I may have changed a few of your edits, I hope you don't mind.

There seems to be a lot to do on the bicycle articles here, I'm open to any suggestions of where to start (I've only edited wikipedia very occasionally, but would like to put some work in to the bike stuff.)

That's a good point about most single speed (non-bmx) bikes using a coaster brake, I'd not thought of that. That's probably true for N. American, (I'm Canadian), but I was thinking of the Asian Utility bikes when I wrote that... maybe I can make that make sense. --Keithonearth (talk) 00:43, 29 September 2008 (UTC)[reply]

Keep up the good work. If you get a chance, perhaps you could take a look at Bicycle and motorcycle dynamics, Bicycle and motorcycle geometry, and Bicycle performance. -AndrewDressel (talk) 12:59, 30 September 2008 (UTC)[reply]

Thanks for the encouragement, and Awesome job on the freehub/threaded-hub diagram. I skimed over those articles mention and I gotta say, they intimidate me. I love the bikes, but my knowledge (and collection of reference books) is the nuts and bolts. Don't know 'bout that physics stuff. I'll look them over all the same, maybe there be a few little things I could add. --Keithonearth (talk) 05:13, 1 October 2008 (UTC)[reply]

Hey, I was thinking of editing your Freehub_vs_freewheel_hub to do a cut away section of each to show the bearings. (well, at least to try to) What did you use to make it? Would you have a svg (or other format that inkscape can handle) kicking around somewhere?--Keithonearth (talk) 06:23, 5 November 2008 (UTC)[reply]

No such luck, sorry. I drew it in MS Word. I can send you that, if it would help. -AndrewDressel (talk) 14:09, 5 November 2008 (UTC)[reply]

Thanks for the offer, but I don't think it'll be of use for me in that format. Maybe I'll just do some tracing.--Keithonearth

I seem to be stepping on your toes more than I mean to these days...sorry about that. I just replaced your diagram of a Freehub vs a freewheel hub on the cogset article. I hope you like it, but let me know if you don't. Maybe I/someone can change the diagram I put up. Or maybe both images could go up, but I think the article is a bit to small for that. Let me know what you think.--Keithonearth (talk) 09:13, 4 December 2008 (UTC)[reply]

trail and self stability

Either I missed it in the article, or the article left out the key factor in self stability, which is trail. This is easily demonstrated on bicycles where the front wheel can be turned backwards; by turning the front wheel backwards (assuming forward offset forks, the trail is increased a lot and the bicycle will almost come to a complete stop before falling over. Jeffareid (talk) 01:55, 18 October 2008 (UTC)[reply]

Perhaps the existing text inadvertantly emphasizes the influence of gyroscopic effects on self-stability, simply due to the order of the sections. While I don't doubt the experiment you cite, first we would need a published source for it not to be OR; and second, it only suggests that increasing trail lowers the lower bound of the stable range. It doesn't indicate that trail is necessary nor sufficient for self-stability. -AndrewDressel (talk) 14:09, 18 October 2008 (UTC)[reply]

On a side note, too little trail is one source of speed wobble. This was an issue for the first year production of Honda's 900 RR motorcycle, where speed wobble was an issue when these motorcycles were raced. In the second and later years, the forks were adjusted 3/8" back to increase the trail and eliminate the speed wobble issue. Jeffareid (talk) 01:55, 18 October 2008 (UTC)[reply]

All Cossalter says is that "wobble frequency goes up as trial increases and front-frame inertia decreases". He continues with "[it] is determined mainly by the stiffness and damping of the front tire, although the lateral flexibility of the front fork also plays a part." Can anyone verify that the amount of trail was the only change that Honda made? -AndrewDressel (talk) 14:09, 18 October 2008 (UTC)[reply]

It wasn't the only change, and Honda made the change much later than I thought. The issue created an aftermarket for triple clamps with more trail (less offset), and is mentioned in this Wiki reference to the 1998 model: 5 mm (0.20 in) less triple clamp offset (an almost universal aftermarket upgrade to previous models). Jeffareid (talk) 01:48, 20 October 2008 (UTC)[reply]

You are raising excellent points about the article. Thanks for taking a look at it. -AndrewDressel (talk) 14:09, 18 October 2008 (UTC)[reply]

Bicycle and motorcycle dynamics: trail and self stability

Perhaps you could help out here when you get the time?

Regarding bicycles (or motocycles) I've alway's thought that main source of self stability was fork trail. I've read this in numerous articles, that included the results of actual testing of real bicycles where the trail was varied from negative (no stability) to very positive (lots of stability). However, Andrew Dressel appears to be disputing a relationship between trail snd self stability.

In all the excitement, you might have missed that I actually am Andrew Dressel. -AndrewDressel (talk) 19:49, 18 October 2008 (UTC)[reply]

I've added the following section to the talk page:

trail and self stability

I'm also confused about the capsize speed, since I've never experienced this. The eigenvalues section includes a diagram showing that some model of a bicycle will go unstable at around 18mph. However this speed seems slow. A winning racing bicyclist often goes hand free at the end of a race, well over 30mph, with no apparent instability. Motorcycle races sometimes fall off their bikes at high speeds, and the bikes continue on with no apparenty instability.

Jeffareid (talk) 19:20, 18 October 2008 (UTC)[reply]

The particular eigenvalues plotted are for a utility bicycle, not a race bike nor a motorcycle.
A rider sitting up on his bike with his hands in the air is completely different from a riderless bike. Riding no-hands is not a demonstration of self-stability.

As the article already states: a capsize can happen very slowly if the bike is moving forward rapidly. Because the capsize instability is so slow, on the order of seconds, it is easy for the rider to control, and is actually used by the rider to initiate the lean necessary for a turn. -AndrewDressel (talk) 19:49, 18 October 2008 (UTC)[reply]

I've experienced turning a motorcycle at 100mph (not all out, but at about 80% of maximum grip), and the main difference is that the bike tends to hold it's lean angle (lean stability) as opposed to straightening up (vertical stability), when I wasn't applying any torque to the handle bars. I had to use the same amount of inwards counter steering to straighten up as outwards counter steering to lean over. It was similar to flying a plane with no dihedral effects, once banked, it just held the bank angle (the motorcycle at 100mph). At slower speeds, the motorcycle tends to straighten up and requires a constant amount of outwards counter-steering torque in order to hold a lean angle.

It sounds as though you are experiencing the different behaviours on either side of the so-called inversion speed. As the article already states: at speeds below the capsize speed, also called the inversion speed, the self-stability of the bike will cause it to tend to steer into the turn, righting itself and exiting the turn, unless a torque is applied in the opposite direction of the turn. At speeds above the capsize speed, the capsize instability will cause it to tend to steer out of the turn, increasing the lean, unless a torque is applied in the direction of the turn. At the capsize speed no input steering torque is necessary to maintain the steady-state turn. -AndrewDressel (talk) 19:49, 18 October 2008 (UTC)[reply]

I've always thought that the tendency to straighten up is due to the inwards yaw torque on the steering due to fork trail effect. Regarding the transition into lean stability at high speeds, I've always though that it was due to gyroscopic effets.

Jeffareid (talk) 19:33, 18 October 2008 (UTC)[reply]

I've read about the same neutral handling (no steering required to hold a lean angle) effect not having a known upper limit in articles about motocycle racing. It starts at around 100mph, and continues to feel the same up to the 200mph or so speeds that racing motorcycles reach. Most racing tracks don't have turns at this speed. Daytona has a 180+mph turn, but it's steeply banked. The main exception is the Ilse of Mann (it's a timed event verus a true race), where there are several 150mph to 200mph turns. The racers claim that 200mph turns feel no different than 100mph turns, no steering inputs are required to maintain a lean angle, stereing input are only used to change the lean angle. However the faster you go, the more counter steering force it takes to change the lean angle, and the force is quite large at high speeds. At slower speeds, 80mph or less, some amount of constant counter steering and/or hanging off the motorcycle is required to maintain lean angles to prevent the motorcycle from reducing the lean angle (returning to vertical). The reason stated for neutral handling at high speeds was gyroscopic effects, which resist any change in the roll axis. Yaw torque due to trail on the front wheel should result in some outwards roll precession, but the rate is very small and resisted by the rear tire which is larger and has more momentum. The reason usually given for vertical stability at lower speeds is fork trail. Jeffareid (talk) 20:51, 18 October 2008 (UTC)[reply]

There is a ton of conventional wisdom and lore out there, perhaps largely because the correct equations have been so hard to pin down and so opaque to conventional dynamic analysis. I have yet to see a convincing treatment that teases out what parameter is responsible for what behavior at what speed. That may not even be possible. Another part of the problem could be that there are so many parameters at play. I'm afraid the best we can do in this article at this point is point out that parameters that do contribute.

It may be true that racing motorcycles do not have a capsize speed, but I have not seen physical test data, and the one eigenvalue plot for motorcycles I have seen, by Cossalter, which does appear to have a finite capsize speed does not indicate how complete the model is. Perhaps it doesn't include tire effects, and they increase the capsize speed on real bikes. -AndrewDressel (talk) 22:15, 18 October 2008 (UTC)[reply]

I found some videos testing stability on a treadmill from the Delft bicycle research page. The fastest test is at 30km/h = 18.64 mph, or 8.33 m/sec, (slightly above the stated capsize speed), the bike is very stable. treadmill measurements. Jeffareid (talk) 23:16, 18 October 2008 (UTC)[reply]

Since that page you link to doesn't state a capsize speed, I'm guessing you are refering to the capsize speed stated in this wikipedia article. That value is merely an example calculated for one particular idealized bicycle. I've added some words that I hope make it clearer that the plot of eigenvalues is for one particular bike. -AndrewDressel (talk) 14:28, 19 October 2008 (UTC)[reply]

The capsize speed is shown in a graph on another article from Delft, and it appears to be the same bicycle: Koo06.pdf

The graphs shows capsize speed at below 8m/s, but the tread mill runs shows and states that the bicycle is very stable at 30km/s == 8.64 m /s. I'm waiting for feedback from someone at Delft, but my guess is that tire width is an issue. When leaned over, the contact patch is on the side of the tire, and this offset creates an outwards torque on the roll axis. Tire width and a rear tire much larger than the front tire may explain why the capsize "rate" is imperceptible on motorcycles at high speed. Jeffareid (talk) 23:07, 19 October 2008 (UTC)[reply]

It's been a while with no response. Any new ideas or comments? —Preceding unsigned comment added by Jeffareid (talk • contribs) 20:06, 23 October 2008 (UTC)[reply]

slip angle

slip angle links (plenty of these at various web sites)

Slip angle

Not much for references. One of the three links appears to be broken. -AndrewDressel (talk) 01:28, 21 October 2008 (UTC)[reply]

motorcycle slip angle

I'm leery of these guys. They also claim that the rear wheel and engine provide significant stabilization via gyroscopic forces (The third gyroscope), and they provide no credible source for such claims. -AndrewDressel (talk) 01:28, 21 October 2008 (UTC)[reply]

I seem to recall some square 4 cylinder engines in racing bikes that had counter rotating flywheels, and the riders claimed to notice the difference. Jeffareid (talk) 04:13, 21 October 2008 (UTC)[reply]

camber thrust (again plenty links on this):

Article explaining camber thrust: tyres

While I don't dispute the final results, I don't like the argument used to develop it. They completely ignore the fact that bikes and cars have front and rear tires and the center of curvature is at the intersection of their axes. -AndrewDressel (talk) 01:28, 21 October 2008 (UTC)[reply]

Tiny graph in this link: motorcycle tire information

Seems to agree with Cossalter: camber thrust generates more than enough centripetal force for cornering up to about 30 degrees. Below that, there will actually be negative side slip. Above that, side slip increases rapidly. -AndrewDressel (talk) 01:28, 21 October 2008 (UTC)[reply]

Experiment disputing camber thrust: wheels that don't turn Scroll down web page for this link. It's currently broke though. A description of the experiment: Terry made a rig that consisted of two paper cups and a frame. The axles of the paper cups were parallel to each other. Even though the "outer" diameters of the paper cups were larger than the "inner" diameters, the rig rolled in a straight line.

Ignores the fact that camber thrust is caused by deforming the tire carcass, not simply by the conical shape. -AndrewDressel (talk) 01:28, 21 October 2008 (UTC)[reply]

Which is why I'd like to see the experiment repeated with conical tires that would deform instead of slip. Jeffareid (talk) 04:03, 21 October 2008 (UTC)[reply]

my thought - camber torque versus camber thrust versus slip angle

A cone segment shaped tire turns in a circle because it's contact patch generates an inwards yaw torque as the tire rolls forwards, which causes the tire to turn (yaw) over time and travel in a circular path. The contact patch deforms in normal slip angle mode. As speed increases, the radius will become larger because the slip angle increases with centripetal force, which increases relative to speed^2. The point here is that the cone aspect of the tire creates a (yawing) torque, not a (centripetal) force.

Tires with non-zero camber angle can generate a yawing torque, a centripetal force, or some combination of the two. -AndrewDressel (talk) 01:28, 21 October 2008 (UTC)[reply]

Now expand this to a vehicle with two cone segment shaped tires. The inwards yaw torque from the rear tire produces an inwards force on the front tire. The inwards yaw torque from the front tire is more complicated because the front wheel can yaw (steer). It would produce an outwards force on the rear tire if the steering angle was fixed or resisted by a rider. The net difference in these forces, could be considered camber thrust. These camber related forces would be added to the centripetal related forces on the tires, eventually ending up as conventional slip angle related deformations. Note that the inwards yaw camber torque at the front tire causes it to steer inwards, and this may be factor in capsize speed in the case of a riderless bicycle. Camber torque must be relatively small, because it doesn't prevent a riderless bicycle from being stable within reasonable speed range, and it doesn't exhibit itself as a significant torque felt at the handlebars by a rider.

Wilson and Papadopoulos, citing Cossalter, agree that tire "scrub" torque may be responsible for suppression of the capsize instability at high speed. -AndrewDressel (talk) 01:28, 21 October 2008 (UTC)[reply]

If the two cone shaped tire vehicle had parallel axis, then I'm not sure what happens. Terry Colon did an experiment using paper cups, but the friction was low allowing slippage, and it's possible that the straight line was really a circle with a very large radius. Note that the yawing torque from each tire is resisted by a sideways force by the other tire, so I don't know if there is any net torque or force on the overall vehicle. I wonder what would happen if only one of the tires was cone like and the other was flat?

Jeffareid (talk) 21:02, 20 October 2008 (UTC)[reply]

I can find several examples of authors that claim that side slip causes centripetal force, instead of merely being a symptom of centripetal force. The best treatment I know of online is at http://www.dinamoto.it/ -AndrewDressel (talk) 01:28, 21 October 2008 (UTC)[reply]

In compliance with Newtons 3rd law, and rather than specify cause and effect, I was just trying to state that slip angle deformation coexists with centripetal force. It's my belief that the conical aspect so often referred to as camber thrust is actually a torque and not a linear force. I get the feeling that some of these articles are using the term camber thrust to include factors other than the difference in diameters of the inner and outer sufaces of a contact patch. Then again, perhaps I've generalized the term slip angle too much to include any deformation that results in the effective radius of a turn being larger than the no-load radius of a turn. Jeffareid (talk) 04:03, 21 October 2008 (UTC)[reply]

Regarding camber thrust, if a single tire is rolling along a banked track, does it turn uphill? Jeffareid (talk) 04:03, 21 October 2008 (UTC)[reply]

Stem (bicycle part)

Nice work on the Stem article! 842U (talk) 22:01, 24 November 2008 (UTC)[reply]

Don't mind at all. You made terrific edits, and every bit helps. 842U (talk) 22:14, 24 November 2008 (UTC)[reply]

Happy New Year

Happy new year to you too! I'm looking forward to it. —Preceding unsigned comment added by Keithonearth (talk • contribs) 05:04, 2 January 2009 (UTC)[reply]

I just read your list of bikes. Wow, I'm impressed. My two favourites are the lightspeed with 8speed dura-ace, and the Trek 710. --Keithonearth (talk) 05:46, 7 January 2009 (UTC)[reply]

I put my bikes up on my user page. Nothing as impresive as yours. I've got a geeky obscure tech question for you: does a 8spd Dura-Ace cassette use the same free hub body as 7spd non-Dura-Ace shimano cassettes? I know there's some Dura-Ace specific indexing thing at 8spd (and maybe 9spd), but I'm not sure of the details. (I use 8spd Dura-Ace down-tube shifters on my touring bike, and they don't index right without some non-standard configuration)--Keithonearth (talk) 23:09, 7 January 2009 (UTC)[reply]

Sadly, I do not know if an 8spd Dura-Ace cassette uses the same free hub body as 7spd non-Dura-Ace shimano cassettes. Have you looked here? Wow, you done some awesome traveling? What's your favorite trip? -AndrewDressel (talk) 03:12, 8 January 2009 (UTC)

I did see something on SheldonBrown about Dura-Ace specific indexing issues, that's how I managed to set it up. I just can't remember the specifics. It's sort of related to one thing on the Derailleur gears articles that I added. To make my shifters work with modern 8spd you change the side of the anchor bolt the cable runs to, that affects the actuation ratio. I'm putting a note up there too. Oh, and Ladakh in India is one of my favourite places. It's wonderful for hiking, and minor mountaineering.--Keithonearth (talk) 10:14, 9 January 2009 (UTC)[reply]

Pictures

Any chance of taking a picture of a shifter? -AndrewDressel (talk) 12:20, 9 January 2009 (UTC)

I took a couple snapshots today, but I'm not sure what you had in mind, as there's some fine shots on the shifter page. Some, it would seem, taken by you. Anyways, I've got one of a new shimano trigger sifter not installed, and one of my prized dura-ace down tube shifters.--Keithonearth (talk) 06:36, 10 January 2009 (UTC)[reply]

Regarding steering

Andrew first of all i'd like to thank you immensely for clearing my doubt on steering. My peanut brain wasnt able to understand how the centripetal force was in the radial direction. Your explanation clarified the matter "a little". Circular geometry of wheel is the reason i've now realised. Thats why a crate given an initial velocity will be brought to rest by friction (whatever be its orientation) whereas a wheel (with its plane at an angle to its velocity vector) will take a turn because a component of the friction will change its W and bring the V(along that direction) equal to R*W thereby vanishing the friction. We discussed it here : http://en.wikipedia.org/wiki/Talk:Bicycle_and_motorcycle_dynamics#Turning._Explanation.3F

Now my doubt: The basis of your explanation is the decomposition of the initial longitudinal friction to two components. The one along the wheel plane will modify W and V(along the wheel plane) such that V=R*W. (same story. But don't yawn!) But what if the wheel's initial W is set such that the component of velocity along the wheel plane is equal to R*W. The work of the component of the friction has already been done. So will the net friction become zero? What would happen then? P.S: I'm posting this in the talk page of "Bicycle and motorcycle dynamics" wiki article too. —Preceding unsigned comment added by 117.193.196.97 (talk) 14:42, 15 April 2009 (UTC)[reply]

Can't understand

I'm very puzzled by this revert, As best I know, centrifugal force does not exist, a consistent discussion of forces must use the concept of centripetal forces. You obviously understand this quite well and there's lots been going on in discussion. Can you explain what I did wrong that needed tearing up? MalcolmMcDonald (talk) 20:41, 2 May 2009 (UTC)[reply]

Although centrifugal force is described as fictitious, it still conveniently describes why a bike must lean and makes for an easy calculation of the exact angle. You state that "this leaning creates the centripetal force needed to deviate machine and rider from their state of uniform motion in a straight line," when it is the tires that create the centripetal force necessary to change the direction of any wheeled vehicle and leaning is only required on single-track vehicles to maintain balance. I cannot imagine how nor do I know of a source that agrees that the lean creates any centripetal force. -AndrewDressel (talk) 03:09, 3 May 2009 (UTC)[reply]

Lean does result in a centripetal force. Lean towards the left and you would steer left 'a bit'. This is because, a rotating wheel "left-slanted" would have a torque(generated by the normal force) in the direction opposite to the direction of travel. The angular momentum points towards the left. So the wheel deflects to the left. (The resultant angular momentum vector chases the torque!) Steering is a consequence. The driver should prevent this deflection by the use of the handle-bar. Hence gyroscopic effect is a major contributor for stability i think. And andrew you haven't answered the previous question. If you didnt understand, i'm ready to elaborate on it. 117.193.195.158 (talk) 13:33, 3 May 2009 (UTC)Ganesh[reply]