User talk:AndrewDressel

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Contents

[edit] 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!  -SCEhardT 06:51, 30 May 2006 (UTC)

[edit] 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)
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. —xyzzyn 16:08, 30 July 2006 (UTC)
…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. —xyzzyn 12:48, 31 July 2006 (UTC)
- 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)
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. —xyzzyn 13:37, 31 July 2006 (UTC)
  • 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)

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)
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. —xyzzyn 13:37, 31 July 2006 (UTC)

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

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)
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. —xyzzyn 14:19, 8 August 2006 (UTC)
Okay, I'll work on getting you a file. -AndrewDressel 14:31, 8 August 2006 (UTC)

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

-Ha ha. Which employer would that be? -AndrewDressel 03:26, 8 August 2006 (UTC)
Cornell University, I assume from your website. Did you create those images as part of your work for Cornell? —xyzzyn 14:19, 8 August 2006 (UTC)
-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)
I guess it’s OK, then. (For future reference, see the last section of s:GPL for useful information.) —xyzzyn 15:07, 8 August 2006 (UTC)

[edit] 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. —xyzzyn 17:49, 4 August 2006 (UTC)

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)

[edit] 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)

[edit] 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)

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)
How then do you create the necessary lean? -AndrewDressel 03:13, 29 October 2006 (UTC)
At the lowest speeds, you don't lean. Dave 17:01, 29 October 2006 (UTC)
Then how does one counter the Centrifugal force? -AndrewDressel 19:54, 29 October 2006 (UTC)
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)
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)

[edit] 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.  ;) Unfocused 03:28, 1 November 2006 (UTC)

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)

[edit] 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)

[edit] 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)

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)

[edit] bicycle and bicycle gearing

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

[edit] Motorcycle Forks

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

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

[edit] Coaxial steering front suspension

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

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)

[edit] 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)


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

[edit] 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)

[edit] 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)

[edit] 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)

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)

[edit] Welcome!

Hi, and welcome to the Aviation WikiProject! As you may have guessed, we're a group of editors working to improve Wikipedia's coverage of topics related to aviation.

A few features that you might find helpful:

If you have any questions, please don't hesitate to ask one of the experienced project members, and we'll be happy to help you. Again, welcome! We look forward to seeing you around! Trevor MacInnis (Contribs) 13:01, 25 March 2007 (UTC)

[edit] 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)

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

[edit] 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)

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)
Yes, it is. Thanks. Hope my additions stick this time. -AndrewDressel 04:27, 7 April 2007 (UTC)
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)
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)
Nope. Bought the bike back east. Haven't been to a dealer out here yes. -AndrewDressel 04:27, 7 April 2007 (UTC)

[edit] 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

[edit] 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)

[edit] 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)

[edit] 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. SeveroTC 22:37, 8 May 2007 (UTC)

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! SeveroTC 20:02, 14 February 2008 (UTC)

[edit] 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)

[edit] 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)

[edit] 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!)

[edit] 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)

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)

[edit] Sociable

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

[edit] 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)

[edit] 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)

[edit] 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)

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)

[edit] 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)

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)

[edit] 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 ρAV2, 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)

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)

[edit] Chicken strips

OK doke. --WoohookittyWoohoo! 17:31, 2 February 2008 (UTC)

[edit] 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! --jwandersTalk 20:25, 14 February 2008 (UTC)

[edit] 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)

[edit] 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)
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...

[edit] 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)

[edit] 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. SeveroTC 14:29, 23 May 2008 (UTC)

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! SeveroTC 10:18, 29 May 2008 (UTC)

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

[edit] 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)

[edit] 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)

[edit] 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)

[edit] 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)

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)
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)
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)
If their lines of action intersect then there is no moment regardless of direction. BigBlueFish (talk) 17:06, 9 June 2008 (UTC)
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)
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)
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)
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)
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)
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)
No hand-waving necessary. It follows directly from the definition of angular momentum about a point, Hp = 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)
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)
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:Mp = rcm/p x macm. 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)