User talk:AndrewDressel/Archive 4

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Happy New Year

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

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)
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)
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)


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)

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 :

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 (talk) 14:42, 15 April 2009 (UTC)

Reply: I don't understand what you are talking about. (maybe you mistook me to be the OP of this section.) I'm talking about the question described in the above section, "Regarding Steering". It has nothing to do with leaning or remaining upright. (talk) 05:11, 4 May 2009 (UTC)Ganesh
Yes, things are all tangled up because you inserted you comments into a conversation I was having with another editor and you did't make it clear that you are a different editor. Please follow these conventions:
  1. Sign your postings with a recognizable name, preferably a Wikipedia user name. It appears you are adding "Ganesh" on after the date and time of your posts. That is not very helpful.
  2. Indent your posts so that they stand out.
  3. Avoid inserting your comments on my talk page into conversations I am already having with another editor.
I am sorry that I have not been able to reply in a timely manner, but your question is complicated and hard to understand. -AndrewDressel (talk) 12:59, 4 May 2009 (UTC)

Sorry. It wasn't any personal discussion. So i thought it wouldn't be wrong for me to take part in it. Anyway sorry again. Regarding my doubt,.. A wheel is cruising through space having its velocity vector at an angle to the wheel plane when its circumference touches a frictional surface. What happens now is described by you in talk page of "Bicycle and motorcycle dynamics". I'm pasting the desired part here.

Suppose that suddenly the front wheel is turned 45° with respect to the direction of travel. Then, as with a sliding block, you would suppose that the friction force vector is exactly opposite the direction of travel. As with any vector, this force vector can be decomposed into perpendicular components: one aligned with the direction the wheel is pointing, and the other aligned with the axis of the wheel. If we suppose that the wheel is free to rotate about its axis, then the component of the friction vector aligned with the direction of the wheel must go to zero (in the idealized case where there are no disipative forces, such as bearing friction or aerodynamic drag, slowing the rotation of the wheel) because any non-zero friction force would simply cause the wheel rotation rate to change and quickly become zero. The only significant non-zero component of the friction vector remaining is the one aligned with the axis of the wheel.

Now what happens if the wheel's initial angular velocity W is set such that R*W is exactly equal to the velocity component in the direction the wheel is pointing? Sganesh 88 (talk) 09:17, 10 May 2009 (UTC)

Hey thanks for that welcome message in my talk page Andrew! (or was it an automatically generated one? :O ) Sganesh 88 (talk) 13:06, 11 May 2009 (UTC)

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)

Although centrifugal force is described as fictitious, it still conveniently explains 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)

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.

Sure leaning a spinning front wheel to the left causes it to precess to the left, but how is this lean to the left created? Do you mean by the rider leaning to the right with respect to the bike? Do you mean to say that steering is done by leaning and not by applying torque to the handlebars? It certainly can happen, as when riding no-hands, but is not necessary nor particularly effective.

Reply:Yes. I didn't say it is effective. But a slight steering CAN be achieved by leaning. What handle bar does is done by leaning-deflecting the wheel- WHICH results in the generation of centripetal force by the usual procedure which you explained in the talk page of the article under "Turning. Explanation?". (talk) 05:11, 4 May 2009 (UTC)Ganesh

However, you have not explained from where any centripetal force might come. The only source of centripetal force of which I know is the friction between the wheels and the ground. As I have stated before, any wheeled vehicle uses this to turn, and no leaning is required unless it is single-track. Why then, do you continue to assert that lean creates centripetal force? -AndrewDressel (talk) 14:42, 3 May 2009 (UTC)

Reply: Yes. It is the same friction. As i said before the leaning creates a deflection of wheel about the vertical axis which is usually done with the help of the handle bar. (talk) 05:11, 4 May 2009 (UTC)Ganesh

Hence gyroscopic effect is a major contributor for stability i think.

Yes, it can be. -AndrewDressel (talk) 14:42, 3 May 2009 (UTC)

And andrew you haven't answered the previous question. If you didnt understand, i'm ready to elaborate on it. (talk) 13:33, 3 May 2009 (UTC)Ganesh

I believe I have answered your question twice already, first in the edit summary and again above. I reverted your edit because you added the claim that "this leaning creates the centripetal force needed to deviate machine and rider from their state of uniform motion in a straight line." You have not provided a source that supports this claim nor have you explained how it could be true. Also, neither you nor I know that "remaining upright is the primary goal of riding," and I don't know why you added an external link to a Wikipedia article. With all of that, it was far easier to revert than crawl through the paragraph and fix each issue. -AndrewDressel (talk) 14:42, 3 May 2009 (UTC)

I still don't understand as much as you two do on this subject, and I've obviously tripped up with my edit, claiming that leaning produced centripetal force. But seeing "centrifugal force" in a technical article sets my teeth on edge. I'm sure there's something better. MalcolmMcDonald (talk) 16:37, 3 May 2009 (UTC)
First, let me apologize. Apparently some other editor has inserted himself into our conversation. I mistook his comments for yours. I do understand some of the controversy about centrifugal force, what with it being described as fictitious and all, but it remains the simplest and straight-forward way to describe some situations. I also wish there was a better way. In the article itself, I try to avoid the issue with "to balance the relevant forces: gravitational, inertial, frictional, and ground support." At least we agree on the centripetal force. Phew! -AndrewDressel (talk) 12:59, 4 May 2009 (UTC)

No hands

I know that you can lean on a bicycle and cause the bicycle to turn without turning the handle bars. Is that explanable.WFPM (talk) 16:29, 30 April 2010 (UTC)

Sure, if the front assembly is free to rotate about the steering axis, otherwise no. It is explained in Bicycle and motorcycle dynamics#No hands. -AndrewDressel (talk) 18:20, 30 April 2010 (UTC)
Your animated model shows it steering to the left as it turns to the left, and I think that is correct. But I think you do first steer to the right before you steer to the left, so now I'm even more confused.WFPM (talk) 18:46, 30 April 2010 (UTC)
The animation is consistent with the description "this leftward lean of the bike will cause it to steer to the left and initiate a right-hand turn." In both cases when the bike leans to the left, it then steers to the left, and ends up in a turn to the right. The only difference between the two is the rider's motion relative to the frame. - AndrewDressel (talk) 19:30, 30 April 2010 (UTC)

GA reassesment


I have not forgotten/ignored your changes. Thanks for taking this seriously. I will find the time to reply to your statements properly in the next few days. User A1 (talk) 07:41, 14 May 2009 (UTC)


It is indeed AWB, and I have added the legend "and gen fixes" to the edit summary. AWB re-arranges the footnotes into numerical order thus insteat of [18][8] we have [8][18].Rich Farmbrough, 00:21 19 May 2009 (UTC).

NowCommons: File:Three speed shifter.JPG

File:Three speed shifter.JPG is now available on Wikimedia Commons as Commons:File:Three speed shifter.JPG. This is a repository of free media that can be used on all Wikimedia wikis. The image will be deleted from Wikipedia, but this doesn't mean it can't be used anymore. You can embed an image uploaded to Commons like you would an image uploaded to Wikipedia, in this case: [[File:Three speed shifter.JPG]]. Note that this is an automated message to inform you about the move. This bot did not copy the image itself. --Erwin85Bot (talk) 19:05, 26 May 2009 (UTC)

Nonconstant mass in Newton's 2nd Law

Hi Andrew. I saw that you replied to the topic Talk:Newton's_laws_of_motion#Non-constant_mass_in_the_second_law. I wonder if you might take a look and see what you think of my response. Thanks! MarcusMaximus (talk) 06:06, 8 June 2009 (UTC)

Hot air balloon GA Sweeps: On Hold

I have reviewed Hot air balloon for GA Sweeps to determine if it still qualifies as a Good Article. In reviewing the article I have found several issues, which I have detailed here. I am sending you this message since you are a contributor to this article (as determined by this tool). I figured you would be interested in assisting with further improving the article. Please comment there to help the article maintain its GA status. If you have any questions, let me know on my talk page and I'll get back to you as soon as I can. --Happy editing! Nehrams2020 (talkcontrib) 03:45, 16 June 2009 (UTC)

DYK for Camber thrust

Updated DYK query On June 18, 2009, Did you know? was updated with a fact from the article Camber thrust, which you created or substantially expanded. If you know of another interesting fact from a recently created article, then please suggest it on the Did you know? talk page.

Wizardman 08:35, 18 June 2009 (UTC)

RefDesk question: Staying upright on a bike

I noticed that you are one of the main authors of Bicycle and motorcycle dynamics - an excellent article by the way - and thought that you might be interested in providing input at the reference desk question linked above. Cheers. Abecedare (talk) 07:51, 16 July 2009 (UTC)


A/s does not affect the steady state weight transfer at all. A/S can be used to suppress any visible rocking effect. Is A/s really a great link in context? Greglocock (talk) 12:25, 4 August 2009 (UTC)

Local Bike Shop Article Bias

I'm curious why it is okay to reference Performance Bike and Bike Nashbar (owned by Performance Bike) and not any other on-line vendor? When I tried to add competing vendors you deleted my comments. Do you work for Performance too? —Preceding unsigned comment added by PBulebar (talkcontribs) 23:12, 13 August 2009 (UTC)

No. I have no connection to Performance or Nashbar. I have made over 5000 edits over the last 3 years to a variety of bike and physics related articles. Your user ID however, appeares to have been created purely for the purposes of adding links to and to a couple of Wikipedia articles. That is considered link spam, and that is why I reverted your additions. -AndrewDressel (talk) 02:22, 14 August 2009 (UTC)

DYK for Pedersen bicycle

Updated DYK query On September 21, 2009, Did you know? was updated with a fact from the article Pedersen bicycle, which you created or substantially expanded. You are welcome to check how many hits your article got while on the front page (here's how) and add it to DYKSTATS if it got over 5,000. If you know of another interesting fact from a recently created article, then please suggest it on the Did you know? talk page.

BorgQueen (talk) 22:07, 21 September 2009 (UTC)


Oops, sorry! Thannks for imforming me. *Pepperpiggle**Sign!* 01:17, 26 September 2009 (UTC)

Serial bicycle

Hi Andrew. Serial bicycle means a bicycle that be purchased at a shop, as opposed to a custom made or a prototype one. Shall we rename it to "series production bicycle" ? --Jordiferrer (talk) 18:38, 15 November 2009 (UTC) (talk) 03:03, 16 November 2009 (UTC)

Andrew- why is it I write something and when I am finished I send four (talk) 03:03, 16 November 2009 (UTC) and it comes out instead of Sandy Morton and a time stamp?

You need to be logged in as Sandy Morton in order for it to work. Otherwise the system doesn't know who you are and just uses your IP address. -AndrewDressel (talk) 03:41, 16 November 2009 (UTC)

this is a test! I signed in as Sandy Morton, let's see if four tildes work08:27, 18 November 2009 (UTC) —Preceding unsigned comment added by Sandy Morton (talkcontribs)

I'll try again. Sandy Morton 08:28, 18 November 2009 (UTC) —Preceding unsigned comment added by Sandy Morton (talkcontribs)

Eureka! It works. Andrew did you receive my email with several pages from Gillispie's book a day or two ago? Sandy Morton 08:30, 18 November 2009 (UTC) —Preceding unsigned comment added by Sandy Morton (talkcontribs)

Centurion (bicycle)

I wish I could find more sources for the article. It's tough: defunct company, pre-internet. Would you nominate the article?842U (talk) 12:04, 26 November 2009 (UTC)

A question that might interest you

I just posted a question on the accuracy of the equation we've got on the spoke page for determining the length of bicycle spokes. It seems like something that might interest you, and/or something that you could be a help with. Thanks! --Keithonearth (talk) 07:28, 13 December 2009 (UTC)


Can you remove or refactor this comment? It comes across as a bit of a personal attack on the other editor. Cheers, tedder (talk) 19:16, 26 December 2009 (UTC)

Good catch. Thanks. -AndrewDressel (talk) 19:28, 26 December 2009 (UTC)