Talk:Bicycle suspension

damping vs dampening

While I can't yet find a source that explicitely addresses which is correct, dictionary.com defines

damping

1. a decreasing of the amplitude of an electrical or mechanical wave.
2. an energy-absorbing mechanism or resistance circuit causing this decrease.
3. a reduction in the amplitude of an oscillation or vibration as a result of energy being dissipated as heat.

dampening

1. to make damp
2. to deaden, restrain, or depress

SRAM uses 'damping' to describe their products (Rock Shox) on their web site. So does Fox Racing. It seems that damping would be prefered. Should 'dampening' stay in just for completeness? Is there a manufacturer that uses 'dampening'? -AndrewDressel (talk) 18:48, 1 February 2008 (UTC)

Okay, without a reference, such as a manufacturer that uses 'dampening', it should come out. -AndrewDressel (talk) 13:33, 14 March 2008 (UTC)

damping is the correct term, dampening is used incorrectly at times. You made the right decision. Tremanaps (talk) 18:35, 31 December 2008 (UTC)

short link suspensions

There are quite a few other suspension systems that have come along that all fall into a category that I'm terming "short link" based on their appearance. These include: Balfa's dual link suspension from the 2-Step, BMC's APS system, Canfield Brother's parallel link suspension, Giant Bikes's Maestro, Niner Bikes CVA suspension, Lapierre's thing, whatever it is.

Here is what I propose should be included so far. Probably some kind of chronological order of when designs were introduced to the marketplace. For example, the Balfa 2-Step was introduced in 1999, and Niner Bikes showed a nearly identical version called CVA 7 years later. Canfield Brothers have been building what they call "parallel link" bikes since 2001. Based on prior art and use, it is understood that none of these designs are patented or at this time, even patentable. Based on the bicycle industry's fixation on patents, and IP, some discussion about the suspensions as it relates to patented designs should exist, especially in light of the widely understood situation with Giant's Maestro and the BMC designs and the previously patented dw-link. A similar discussion should be had about Lapierre's bikes and Santa Cruz's VPP patents. Another area that would be good to talk about is the reality of these suspension designs and performance. Most of these designs perform similarly to single pivot bikes when it comes to acceleration. All too often, wild claims are made about performance, when the actual product is incapable of "living up to the hype". Perhaps this could be the start of a different section altogether? Tremanaps (talk) 13:29, 3 February 2009 (UTC)

Good luck. It sure could use some organization. -AndrewDressel (talk) 14:04, 3 February 2009 (UTC)

Yep. The article should definitely include designs like CVA and Maestro.Laxman2001 (talk) 00:33, 5 March 2010 (UTC)

Mass transfer -vs Load Transfer

I read a comment by Andrew D that said [Newton's_3rd_law#Newton's laws of motion:_law_of_reciprocal_actions|Newton's 3rd law] does not impart ...

Newton's third law states that "Every action has an equal and opposite reaction" Tremanaps (talk) 18:41, 27 March 2009 (UTC)

Yes, and what that means is simply "for a force there is always an equal and opposite reaction: or the forces of two bodies on each other are always equal and are directed in opposite directions." In the case of an accelerating vehicle it means that the earth pushes on the vehicle exactly as much and in exactly the opposite direction as the vehicle pushes on the earth. -AndrewDressel (talk) 21:57, 29 March 2009 (UTC)

A vehicle has mass. A vehicle's complete mass can be broken down into sprung mass and unsprung mass. A vehicle can have multiple unsprung masses and masses. Each mass amount has a measurable value (weight) and centroid (also known as center of mass). A vehicle like a full suspension bicycle has a compliant rear wheel suspension, which allows the rear wheel to move independently of the chassis. When a vehicle accelerates, it's complete mass is accelerated forward. In newton's third law, and for the discussion at hand, this vehicle acceleration can be regarded as the Action. As the vehicle sits at rest on flat ground, gravity's action on it's mass produces a measurable load or weight at each wheel. As the vehicle accelerates, the measured load of the sprung mass transfers rearward to the rear tire. This can be regarded as the Oppposite Reaction in Newton's third law. Tremanaps (talk) 18:41, 27 March 2009 (UTC)

No, this is not what the 3rd law is about. Instead, this is an application of Newton's second law, F=ma, when generalized to moments. The wheels generate a net moment about the vehicle's center of mass, and the vehicle responds by accelerating angularly about them. This is then resisted, in turn as springs compress in the suspension. No rotation is necessary, however, for the wheels to experience a change in load. The braking section of the Bicycle and motorcycle dynamics article gives more details with a good source. -AndrewDressel (talk) 21:57, 29 March 2009 (UTC)

I strongly disagree with your assessment that the above is not a physical realization of Newton's third law. F=MA goes one level deeper into calculations than I have tried to point out. At the base level, Newton's third law correctly and completely characterizes the situation that I propose for discussion. This is not my opinion, it's the realization of an accepted equation that is mathematically based, hundreds of year's old, and taught at the most basic levels of Physics. Tremanaps (talk) 13:32, 30 March 2009 (UTC)

I guess then we are going to need a source that confirms your interpretation of Newton's 3rd Law. All the ones I have simply explain that it states "mutual forces of action and reaction between to particles are equal, opposite, and collinear." That quote is from Engineering Mechanics by Hibbeler. Engineering Mechanics by Schmidt, Engineering Mechanics by McGill and King, Engineering Mechanics by Bedford and Fowler, Dynamics by Tongue and Sheppard, Engineering Mechanics by Meriam and Kraige, and Vector Mechanics for Engineers by Beer and Johnston all agree. In fact, the last two books relegate discussion of the 3rd law to their statics sections. -AndrewDressel (talk) 16:29, 30 March 2009 (UTC)

In my opinion, the core issue behind our very minor debate here is that you are talking about characterizing the dynamic problem, wheras I am simplifying the problem for the sake of this discussion to an instantaneous moment in time, a static problem. F=MA is only a tiny part of the full dynamic problem, whereas Newton's third law, at the base level, and at an instantaneous moment in time (static analysis) sums up the problem simply and completely. The quotes that you have provided support this. Tremanaps (talk) 13:10, 31 March 2009 (UTC)

First, it is only a dynamics issue. Without motion, it would not occur, and it cannot be calculated by static methods. Second, I see no point in dumbing down this article to the point of being incorrect. Third, Newton's third law, being only about equal, opposite, and collinear forces, as all the sources I list above confirm, completely does not apply. There is nothing collinear about load transfer or weight transfer. -AndrewDressel (talk) 13:50, 31 March 2009 (UTC)

Almost any dynamic situation can be analyzed statically at an instant in time. There is no "dumbing down this article to the point of being incorrect" as you state. I am sorry that you are having a hard time understanding what is presented here, but it is what it is. I suggest that you take some time to analyze the problem, consult with experts, and reconsider the problem after you have some time to think about it.Tremanaps (talk) 12:09, 1 April 2009 (UTC)

I am not having any trouble with what is presented here. I am simply correcting a misinterpretation of Newton's laws. His third law is strictly about the equal, opposite, and collinear pairs of forces between particles, as the published sources mentioned above confirm. Weight transfer is covered generally under his second law and specifically under Euler's second law. Unless you can provide a verifiable reliable source that provides a different interpretation of these laws, I consider this matter closed. -AndrewDressel (talk) 05:05, 2 April 2009 (UTC)

I'll take that as meaning no such source can be found. Newton's 3rd law does not apply. -AndrewDressel (talk) 23:45, 10 April 2009 (UTC)

This load transfer can be measured as a weight difference at the rear wheel during acceleration. This principle is discussed in detail in several textbooks on the subject. Milliken and Milliken's Race Car Vehicle Dynamics; Thomas Gillespie's Fundamentals of Vehicle Dynamics are both examples of books where this terminology and basic explanation are depicted. Fundamentals of Vehicle Dynamics is a common textbook for Vehicle Dynamics students.Tremanaps (talk) 18:41, 27 March 2009 (UTC)

I've thought about this overnight, and regardless of fact that the textbooks seem to use the terms "load transfer", "weight transfer", and "mass transfer" interchangeably, load transfer is probably the best to describe the physical action. I propose that we choose "load transfer" for all future discussion so as to keep things simple and as accurate as possible.Tremanaps (talk) 14:48, 29 March 2009 (UTC)

While wikipedia articles should not be uses as a source, of course, and the current [load transfer] and [weight transfer] articles do not cite any sources, I think a good goal is for all these articles to be consistent. They currently make strong distinctions between the terms, and this article should match or they should be corrected. I, sadly, do not have one of the vehicle dynamics texts mentioned above. -AndrewDressel (talk) 21:57, 29 March 2009 (UTC)

I suggest that you read the suggested text before making any further assumptions or assertions, as these texts (and not a wikipedia article) are two of the accepted textbooks for suspension dynamicists. (Milliken and Milliken's Race Car Vehicle Dynamics (ISBN:1-56091-26-9); Thomas Gillespie's Fundamentals of Vehicle Dynamics (ISBN:1-56091-199-9))Tremanaps (talk) 13:32, 30 March 2009 (UTC)

Here are some bike specific sources instead.

• Cossalter, in his Motorcycle Dynamics, on page 84 says "Load transfer" refers to the fact that there is a decrease in the load on the front wheel and a corresponding increase in the load on the rear wheel.
• Foale, in his Motorcycle Handling and Chassis Design, on page 9-1 says This is normally referred to as weight transfer, but that is really a misnomer. Weight is the gravitational attraction of all the particles in the bike towards the centre of the earth, and for convenience we usually consider the sum of these forces to act through the CoG. Neither acceleration nor braking can cause this weight to transfer elsewhere. As a result the use of the term 'load transfer' is preferable.
• Cocco, in his Motorcycle Design and Technology, on page 40 says We must calculate a variation in the vertical loads acting on the wheels. The same component is referred to in the literature as weight transfer.

I find Foale's argument pursuasive and so agree with you on this point, as I did in my original edit that sparked this debate. I've already updated the load transfer and bicycle and motorcycle dynamics articles with these sources. -AndrewDressel (talk) 13:50, 31 March 2009 (UTC)

Here are some non-bike specific sources.

• Jazar, in his Vehicle Dynamics, on page 72 says The higher the C, the more load transfer. He does not appear to define the term explicitly and does not list it in the index.
• Newcomb, in his Braking of Road Vehicles, on page 23, in a section titled Weight Transfer says during braking less load is carried on the rear and more on the front than when the vehicle is stationary, but then continues with Motor cycles [sic] and scooters present an extreme case of weight transfer.

I still like the case Foale makes above. -AndrewDressel (talk) 20:00, 31 March 2009 (UTC)

Interesting that there are so many varying nomenclatures, huh? Why do you think that is? Maybe, just maybe, not everyone who's published has it exactly right. Use your brain to understand, and textbooks as a guide.Tremanaps (talk) 12:09, 1 April 2009 (UTC)

I see it all the time, and I have helped clean up conflicting definitions from the literature like this on several occasions, as I mention on my user page. There is often no 'right' or 'wrong', just different authors using different terms to mean the same thing or the same term to mean different things. In this case it could be a matter of authors not writing in their native language; Cossalter and Cocco are Italian, I believe. The best hope is to find an established author, such as Sheldon Brown, or in this case Tony Foale, who makes sense of the situation. Without that, all we can do is explain the different usages as clearly as possible. To do otherwise is to introduce original research, which might be fine on some other site but strictly forbidden here. -AndrewDressel (talk) 05:05, 2 April 2009 (UTC)

I still haven't found a source that uses "mass transfer" as in the text I removed from the article that sparked this discussion. That appears to have been copied from promotional material on the dw-link website. Do either of the two sources you mention above use "mass transfer"? Can you provide a quotation? -AndrewDressel (talk) 17:21, 2 April 2009 (UTC)

I'll take that as meaning no such source can be found. "Mass transfer" is not a term used in the literature to describe this phenomenon. -AndrewDressel (talk) 23:45, 10 April 2009 (UTC)

Iron Horse bicycles as dw-link licensee

Numerous reports and interviews with the designer confirm that the relationship was ended by Dave Weagle in 2007. -anon.

Since both the DW-Link website, which lists Iron Horse as a partner, and the Iron Horse website which lists DW-Link as a technology used in the 2009 Sunday, suggest strongly that Iron Horse is a current licensee of the DW-Link technology. And since interviews with the designer, unless published, are not verifiable sources, as required here on Wikipedia, could we have links or publishing information; author, date, publication, etc.; of at least one of the numerous reports that confirm that the relationship was ended by Dave Weagle in 2007. -AndrewDressel (talk) 17:35, 7 September 2009 (UTC)

Here is a link from an interview with the designer. This was published online and in print. The first question addresses the cessation of license to Iron Horse. This took me 10 seconds to find with Google. Less time most likely than it took you to write your post..

http://bikemag.com/features/onlineexclusive/dave-weagle-interview/ -76.24.199.56 (talk) 07:47, 19 September 2009

Thanks for contributing that 10 seconds. -AndrewDressel (talk) 21:01, 18 September 2009 (UTC)

Bias

trek were independantly awarded a patent for the abp design as they were shown to have developed prototypes before weagle filed his patent. even if they hadnt been awarded the patent they could still have used the system in a simlar fashion to turner uding the fsr/ horst link system without having to pay specialzed as they were already using the system before the patent was awarded. also this article is biased towards one company and should be editted to remove this bias. - 141.163.196.38 07:31, 11 February 2011

It would be great to find sources to confirm any of this. -AndrewDressel (talk) 19:06, 10 February 2011 (UTC)

If the names of the inventors/patent holders need to be mentioned, then I think it would be ok to mention that the matter is currently being settled in the court. A search engine will provide enough news to cover the matter in detail. — Preceding unsigned comment added by 91.157.17.8 (talk) 13:08, 7 January 2013 (UTC)

useful image

Did anyone else see this image over on commons? Seems like it could be useful for this article. I'm not knowledgeable enough (or particularly into suspension) to insert it myself. --Keithonearth (talk) 23:40, 12 September 2011 (UTC)

Might be useful with the right explanatory text, but it is pretty opaque as is. -AndrewDressel (talk) 00:46, 13 September 2011 (UTC)

High Forward Single Pivot

The previous version of this mentioned that a high forward single pivot suspension compresses when pedaled in the small ring. This is not accurate, so I changed it. The effect is just the opposite: you get an extending force that make the suspension somewhat resistant to compression, thus the term "semi-active". I have assumed this was common knowledge among people who are a well versed in suspension, so I do not have a citation for it. If this is an issue, feel free to remove my edit, but I would also remove that entire section, as the previous version is also not backed with a citation. Kapusta7 (talk) 15:47, 22 August 2012 (UTC)kapusta7

Mountain bikes since early 1990's? What?

Article text:

"Mountain bike technology has made great advances since first appearing in the early 1990s."

This is severely misinformed. While early 1990's may be before the author of the above was born, there certainly existed mountain bikes in the 1980's. In fact, they exploded in popularity around that time.

Forks with shock absorbers appeared on mountain bikes well before 1990.

Citation: I was, like, there.

24.85.131.247 (talk) 05:04, 24 September 2012 (UTC)

So fix it. Find a good source for Gary Fisher riding fat-tyred cruisers downhill and add it. Describe the BMX and cyclocross precursors to MTBs and add them. Whilst agreeing with you that 26" MTBs were sold as such in retail shops in the late '80s, I'm no more WP:RS on this than you are. Andy Dingley (talk) 09:31, 24 September 2012 (UTC)

I'm pretty sure I had a mountain bike in 1984, which is early to mid 80's. The reference we're looking for is in the Wikipedia itself. The Mountain Bike pegs the start of mass production of mountain bicycles to the 1970's to early 1980's. Certain improvements didn't appear until 1990, but it's not clear exactly which ones. Some weren't common on mass produced mountain bikes until later, like disc brakes or rear suspensions. I think it's safe to fix the 1990 reference in this page, in any case. 24.85.131.247 (talk) 05:40, 3 February 2013 (UTC)