VPP vs. Horst/FSR- Mtbr.com
Results 1 to 52 of 52
  1. #1
    mtbr member
    Reputation: SurfSailRide's Avatar
    Join Date
    Dec 2008
    Posts
    919

    VPP vs. Horst/FSR

    Okay so this thread is meant to stimulate (friendly) debate, as well as be informative.

    Question 1: What is VPP and what are its advantages/disadvantages?
    Question 2: What is a "Horst" link, and what are its advantages/disadvantages?
    Question 3: Which bikes use which types of suspension, and who owns the patents?

    ... and the big one...

    Question 4: Hypothetically, in your opinion, If patents were not an issue, would Santa Cruz use FSR? Would Specialized use VPP? Why?

    Let's keep this friendly, folks... Opinions are not facts, but I think this thread can be really helpful for people who are researching which bike to buy.

  2. #2
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    4,445
    not to be a douche, but this has been discussed at length. try using the search before you ask "what is VPP" and "what is horst link" and especially before you ask the advantages of each. There are so many different ways you can set a VPP linkage up, and so many ways you can set a horst link up.

  3. #3
    I dig trails!
    Reputation: Mr.P's Avatar
    Join Date
    Feb 2005
    Posts
    5,560
    Quote Originally Posted by William42
    There are so many different ways you can set a VPP linkage up, and so many ways you can set a horst link up.
    +1. It is really about execution and what characteristics are designed into the linkage.

    P

  4. #4
    AW_
    AW_ is offline

    Reputation:
    Join Date
    Jan 2006
    Posts
    1,443
    I'm of the opinion that on a bike that is well designed and executed... the actual suspension format isn't that big of a deal.... to me anyways. I don't limit myself to only wanting to ride a certain suspension type. If a bike feels right........ that's all you need. People tend to get too way scientific on the interwebs about it. Technology only makes up for a small amount of skills, the other 95% is the rider.

  5. #5
    mtbr member
    Reputation: boogenman's Avatar
    Join Date
    Sep 2006
    Posts
    1,744
    Put anything other than a Manitou rear shock on any well designed bike and you're in business

  6. #6

    Reputation:
    Join Date
    Jan 2009
    Posts
    8
    Trek, Pacific Cycles and all the other bike companies should get together and tell the U.S. patent office they're on hallucinogens if they think the Horst pivot point deserves a design patent. It's a friggen pivot point.

  7. #7
    TNC
    TNC is offline
    noMAD man
    Reputation: TNC's Avatar
    Join Date
    Jan 2004
    Posts
    12,059

    LOL!...ridiculous.

    Quote Originally Posted by boogenman
    Put anything other than a Manitou rear shock on any well designed bike and you're in business
    That blanket statement makes no sense.

  8. #8
    mtbr member
    Reputation:
    Join Date
    Dec 2007
    Posts
    1,172
    Quote Originally Posted by AW_
    I'm of the opinion that on a bike that is well designed and executed... the actual suspension format isn't that big of a deal.... to me anyways. I don't limit myself to only wanting to ride a certain suspension type. If a bike feels right........ that's all you need. People tend to get too way scientific on the interwebs about it. Technology only makes up for a small amount of skills, the other 95% is the rider.
    I totally agree with that, but for me, and im sure many others, it's difficult to test ride bikes (on actual trails), so the next best thing is to research different designs and their characteristics to find out what may be the best ride for us.

  9. #9
    TNC
    TNC is offline
    noMAD man
    Reputation: TNC's Avatar
    Join Date
    Jan 2004
    Posts
    12,059

    Interesting thought, but...

    Quote Originally Posted by JK09
    Trek, Pacific Cycles and all the other bike companies should get together and tell the U.S. patent office they're on hallucinogens if they think the Horst pivot point deserves a design patent. It's a friggen pivot point.
    Isn't the location of a pivot point in relationship to a linkage the basic "holy grail" of bicycle suspension design success? Research and testing by an individual or company to develop a good working design should have some protection...shouldn't it? Or did you mean something else?

  10. #10
    offroader
    Reputation:
    Join Date
    Dec 2008
    Posts
    2,190
    Quote Originally Posted by TNC
    Isn't the location of a pivot point in relationship to a linkage the basic "holy grail" of bicycle suspension design success? Research and testing by an individual or company to develop a good working design should have some protection...shouldn't it? Or did you mean something else?
    You would think so, but apparently you can write up a blanket concept that revolves around the placement of a pivot point in front of the rear drop out and the U.S. patent office will grant you patent protection, while no other country in the world will.

  11. #11
    TNC
    TNC is offline
    noMAD man
    Reputation: TNC's Avatar
    Join Date
    Jan 2004
    Posts
    12,059
    Quote Originally Posted by CupOfJava
    You would think so, but apparently you can write up a blanket concept that revolves around the placement of a pivot point in front of the rear drop out and the U.S. patent office will grant you patent protection, while no other country in the world will.
    Well...what would be the criteria at what point that a substantive engineering design concept would exist?...and when it wouldn't? I'm not arguing one way or another, but I'd like to know at what point a concept crosses the wire from a vague idea to a specific mechanical reality.

  12. #12
    mtbr member
    Reputation: SurfSailRide's Avatar
    Join Date
    Dec 2008
    Posts
    919
    Quote Originally Posted by TNC
    Well...what would be the criteria at what point that a substantive engineering design concept would exist?...and when it wouldn't? I'm not arguing one way or another, but I'd like to know at what point a concept crosses the wire from a vague idea to a specific mechanical reality.
    That's precisely what the patent office is for.

  13. #13
    Amphibious Technologies
    Reputation: SCUBAPRO's Avatar
    Join Date
    Jun 2004
    Posts
    3,472
    Quote Originally Posted by TNC
    Well...what would be the criteria at what point that a substantive engineering design concept would exist?...and when it wouldn't? I'm not arguing one way or another, but I'd like to know at what point a concept crosses the wire from a vague idea to a specific mechanical reality.
    three words: Reduction to practice
    "The best you've ridden is the best you know" - Paul Thede, Race Tech

  14. #14
    Off the back...
    Reputation: pinkrobe's Avatar
    Join Date
    Jan 2004
    Posts
    2,162
    Does anyone know when the Specialized US patent on the Horst link runs out? It's already been around for 10 years or more...

  15. #15
    pants on head retarded
    Reputation: yurtinus's Avatar
    Join Date
    Jun 2009
    Posts
    256
    Typically speaking, a patent lasts 17 years-- so you can do the maths on it.

    There are a lot of times where I will argue tooth and nail against patents, but in this case you have:

    1) Concrete engineering effort and research going into developing these suspension systems
    2) Specific enough patents to still allow competition (nobody owns "make the rear tire go squish squish")
    3) *Active* development -- in most cases it seems the companies that own these patents build bikes using the tech
    4) Active licensing -- There are a number of manufacturers building Horst / VPP / ICT frames

    I think this is one case of the patent system working exactly as intended, and it makes me happy to have a lot of choice in kick*ss, well designed suspensions

    *edit* -- Just realized I brought a four month old post back from the dead. spose I'll pay more attention next time!
    Last edited by yurtinus; 06-19-2009 at 11:23 AM.

  16. #16
    mtbr member
    Reputation:
    Join Date
    Jun 2009
    Posts
    395
    Here is an interesting article on where VPP came from and who owns it.

    http://www.wrenchscience.com/Intense...es/Frames.html

  17. #17
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586

    My $.02

    I've own 2 full-suspension bikes:
    2004 Stumpjumoer FSR & 2007 SC Blur XC.
    While they are but one example of each design, IMHO, the VPP smokes the horst-link in every way.
    I never use the pro-pedal on the blur. Doesn't need it.
    Pro-pedal and worse yet, the 'brain', are band-aids for a limited design.

  18. #18

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    The horst link is not a suspension design. It's a pivot location within a variety of designs.

  19. #19
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    Quote Originally Posted by Jerk_Chicken
    The horst link is not a suspension design. It's a pivot location within a variety of designs.

    I would tend to disagree - I'm not an expert and any enlightenment is appreciated.

    I don't think it is simply a pivot location. It is a matter of whether the wheel is connected to the main pivot by a single bar or swingarm or if their the wheel is on a separate link/member; the Horst Link coming between them.

    A faux bar - Kona or old skool Trek are the first that come to mind - are essentially single pivot bikes. The pivot position on the faux bar varies greatly. I think the Treks had them several inches above the drop-out, verse a Ventana that has it right on top of the dropout.

  20. #20

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Quote Originally Posted by reformed roadie
    I would tend to disagree - I'm not an expert and any enlightenment is appreciated.

    I don't think it is simply a pivot location. It is a matter of whether the wheel is connected to the main pivot by a single bar or swingarm or if their the wheel is on a separate link/member; the Horst Link coming between them.

    A faux bar - Kona or old skool Trek are the first that come to mind - are essentially single pivot bikes. The pivot position on the faux bar varies greatly. I think the Treks had them several inches above the drop-out, verse a Ventana that has it right on top of the dropout.
    This is an example of how specialized got their 1999 advertising moneys worth.

  21. #21
    mtbr member
    Reputation:
    Join Date
    May 2009
    Posts
    13

    fsr/horst link and vpp

    My experience, not science...

    I rode a fsr design for the past 11 years (Specialized FSR, Norco Shore), and I've been riding a VPP bike (Intense Uzzi VPX) for the past 3 months. I've ridden the bikes on the exact same trails (local mixed climbing/descending plus Whistler). In my experience, the VPP design is superior in the following ways...

    1. It allows the bike to climb better (bike weights were comparable).
    2. The VPP bike is "plusher".

    I know that those two things should be mutually exclusive, but that's been my experience. I'm so impressed that I'm almost prepared to say that all my future bikes will be a VPP design. BTW, I'm 43, 200 pounds, and I've been riding for over 25 years.

  22. #22
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    Quote Originally Posted by Jerk_Chicken
    This is an example of how specialized got their 1999 advertising moneys worth.

    Wow, that is enlightening.
    I'm guessing your Turner doesn't have a Horst-link...

    If it were a non-issue, why would anyone bother to pay Specialized for the right to use it.
    Let me guess, they were actually paying for the sticker, so they could take advantage of the marketing campaign too.

  23. #23

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Pretty much. They're marketing to people like you. There's a whole world of bike companies outside of the one you see. It's way bigger than you think, and many don't have to pay specialized at all, and they still use other designs. How many are still bothering today? Some have a preference, and that's not a problem at all. I respect that, but it's not a fool-proof and automatic way to get great suspension performance.

    Additionally, it has nothing to do with my own personal bike choice. I've ridden and owned both styles and know it has more to do with the overall design than one pivot point. I've also ridden "horst link" equipped bikes that ride like crap. It's not a guarantee that there is a particular riding trait. Just look at the example of the Jamis bikes from a few years ago, GT's LTS, and Giant's NRS. None of them worked as the horst link was thought to. In fact, they worked contrary. There are many more designs that will also have essentially non-functional HL's. More HL's than you think don't work like the pivot is supposed to work.

    So yes, many companies do pay for a sticker. In about 1999 or so, Specialized started releasing charts showing supposed differences in performance between some non-HL equipped designs and Specialized. Such things as braking performance, pedaling, etc. First, they never qualified their tests, like the testing conditions, and if it was even subjective, or how they measured the differences.

    The next part was they altered the scale of the graphs so there wasn't much comparability and also so people who are too lazy to read the results closely would be wowed by a big difference between the lines of the competition and specialized. In reality, whatever difference there was, it was only in the single digits, percentwise. However, since they altered the scale of the graphs and people are generally lazy and don't read closely, they thought it was huge. It also didn't take into account the overall design, not just a pivot position, like Specialized.

    Specialized also invented the "four bar vs faux bar" debate, which is utterly ridiculous. The same number of members exist. Another additional is that some manufacturers have seen and shown that the wheel path does not vary to any appreciable degree, which is what determines most of the ride. Furthermore, some manufacturers were also able to dispell the specialized-invented myth of "brake jack" the moment one doesn't use an HL. Some companies even design in squat, and even specialized's own tests showed that the HL doesn't eliminate braking and pedaling influence, but negligibly reduced it, again, unqualified.

    This is not 1999 anymore and lots of good choices are out there.

  24. #24
    Elitest thrill junkie
    Reputation: Jayem's Avatar
    Join Date
    Jul 2005
    Posts
    32,570
    Quote Originally Posted by Jerk_Chicken

    So yes, many companies do pay for a sticker. In about 1999 or so, Specialized started releasing charts showing supposed differences in performance between some non-HL equipped designs and Specialized. Such things as braking performance, pedaling, etc. First, they never qualified their tests, like the testing conditions, and if it was even subjective, or how they measured the differences .
    There are probably still people out there with specialized bikes that think they have a "vertical" wheel path.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  25. #25

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    You remember that too? I remember Doug Bradbury was trying to pull the same crap, with respect to that "Tomac Signature Pivot", along with drawings and lines that made the axle path a perfectly vertical line. The hysterics of what we believed, and how these folks got their advertising money's worth, some ten or more years later. Hell, can't blame Spec, as it was their business, and they had a budget, to try and make anything else look like crap.

    Amazing how some people can't imagine that 17 years later, through technical analysis, engineering, experience, and the evolution of different riding disciplines that anything else could be equal, or better.

    All based on one company's advertising...

  26. #26
    mtbr member
    Reputation:
    Join Date
    Jan 2006
    Posts
    260
    Quote Originally Posted by rottenron
    My experience, not science...

    I rode a fsr design for the past 11 years (Specialized FSR, Norco Shore), and I've been riding a VPP bike (Intense Uzzi VPX) for the past 3 months. I've ridden the bikes on the exact same trails (local mixed climbing/descending plus Whistler). In my experience, the VPP design is superior in the following ways...

    1. It allows the bike to climb better (bike weights were comparable).
    2. The VPP bike is "plusher".

    I know that those two things should be mutually exclusive, but that's been my experience. I'm so impressed that I'm almost prepared to say that all my future bikes will be a VPP design. BTW, I'm 43, 200 pounds, and I've been riding for over 25 years.
    But is it really because of the different way the rear part of the frame is connected to the main part? No one can tell.
    IMO "plushness" is mainly a result of the leverge rate curve design (that can be done with all linkage systems)
    and not so much a result of the axle path. Axle path is (generaly speaking) responsible for "side effects", negative and positive, like chain growth, braking and accelaration squat, etc.
    The hard part is combining both elements I mentioned above. Is it possible that Intense did a better job in overall design??? You could only compare if you could ride an fsr Uzzi....

  27. #27
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    Quote Originally Posted by Jerk_Chicken
    Pretty much. They're marketing to people like you. There's a whole world of bike companies outside of the one you see. It's way bigger than you think, and many don't have to pay specialized at all, and they still use other designs. How many are still bothering today? Some have a preference, and that's not a problem at all. I respect that, but it's not a fool-proof and automatic way to get great suspension performance.
    Sorry, I don't recall this insidious marketing campaign you keep mentioning. I was road racing then, reading Cycle Sport instead of MBA...or Mountain Biking.

    While a design, any design, poorly executed will preform poorly, people like me realize that there is something to having the rear axle not directly connected to the main pivot.
    People like me are thinking that bikes companies like Cube and Lapierre, uneffected by any patents, can place that rear pivot anywhere they want and opt for the chain stay instead of the seat stay.

    Anyway, I am currently under the control of the Santa Cruz marketing campaign.


    I am thankful there are experts like yourself to steer people like me in the right direction.

    I have to go now, so I can inject some float fluid into my air chamber with a pump
    That 26mm ratchet was taking sooooo long to use.

  28. #28
    mtbr member
    Reputation: cort's Avatar
    Join Date
    Mar 2004
    Posts
    893
    Quote Originally Posted by reformed roadie
    Sorry, I don't recall this insidious marketing campaign you keep mentioning. I was road racing then, reading Cycle Sport instead of MBA...or Mountain Biking.

    While a design, any design, poorly executed will preform poorly, people like me realize that there is something to having the rear axle not directly connected to the main pivot.
    People like me are thinking that bikes companies like Cube and Lapierre, uneffected by any patents, can place that rear pivot anywhere they want and opt for the chain stay instead of the seat stay.

    Anyway, I am currently under the control of the Santa Cruz marketing campaign.


    I am thankful there are experts like yourself to steer people like me in the right direction.

    I have to go now, so I can inject some float fluid into my air chamber with a pump
    That 26mm ratchet was taking sooooo long to use.
    Was this actually suggested by someone on these forums? Forshame!

  29. #29

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    He's actually misquoting. It's fine and consistent, considering he's a bit uninformed anyhow.

  30. #30
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    Quote Originally Posted by Jerk_Chicken
    He's actually misquoting. It's fine and consistent, considering he's a bit uninformed anyhow.
    REALLY?
    Is your handle not attached to the Rube Goldberg system for adding lubrication to the air chamber of a Fox fork?

    Just click on the DIY link below Mr. Chicken's name.

    If I am uninformed, where does that put you?
    Last edited by reformed roadie; 06-23-2009 at 11:26 AM.

  31. #31

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Quote Originally Posted by reformed roadie
    REALLY?
    Is your handle not attached to the Rube Goldberg sy
    stem for adding lubrication to the air chamber of a Fox fork?

    Just click on the DIY link below Mr. Chicken's name.

    If I am uninformed, where does that put you?
    It's a quick way to get oil into the air chambers. In the case of rear shocks, they weep out oil over time. Sometimes people don't want to open them up (like on trips). For more complex systems, the oil can deteriorate and introduce stiction. This is an easier way to get some lube oil into the system without pulling it apart, like a TALAS system, Zoke's SL and ATA systems. Hell, when one opens the air valves on them, oil comes out.

    You're so uninformed that you don't know people are already doing it, and have been doing it and reporting about it for years, with such things as zoke's SL Doppio cart, like in the 66, their ATA's, and various other air cartridges.

    It's pretty obvious you're uninformed, say from about 1999. There was a window of developments that passed right over your head, but I guess if it's not in a Specialized ad, you don't have to believe it exists.

  32. #32
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    Quote Originally Posted by Jerk_Chicken
    It's a quick way to get oil into the air chambers. In the case of rear shocks, they weep out oil over time. Sometimes people don't want to open them up (like on trips). For more complex systems, the oil can deteriorate and introduce stiction. This is an easier way to get some lube oil into the system without pulling it apart, like a TALAS system, Zoke's SL and ATA systems. Hell, when one opens the air valves on them, oil comes out.

    You're so uninformed that you don't know people are already doing it, and have been doing it and reporting about it for years, with such things as zoke's SL Doppio cart, like in the 66, their ATA's, and various other air cartridges.

    It's pretty obvious you're uninformed, say from about 1999. There was a window of developments that passed right over your head, but I guess if it's not in a Specialized ad, you don't have to believe it exists.
    Don't know where to start...

    The float fluid in the air chamber is simply for lubrication of the piston seals. It is not performing the same function as shock oil, so breakdown is less, if even an issue.
    It's doesn't effect damping, or performance.

    I would be more concerned about adding too much fluid, since the Fox is notorious for ramping up too quickly. A few cc's of excess fluid isn't going to help, considering the relative volume is pretty small. Your system doesn't seem so precise...more like inconsistant and wasteful.

    Why would you use shock oil? You even say that it may effect preformance and require a slight bit of tuning.
    How is all of that quicker than letting the air out, taking off the cap with a 26mm ratchet and turning upside down?

    The concept is much more useful for the rear shock.
    For shame indeed...

    Wow...you're really hung up on the '99 Specialized ad campaign. You really need to get over it. I think my first post said I ditched the FSR for the superior blur XC.
    Last edited by reformed roadie; 06-23-2009 at 08:40 AM.

  33. #33

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Quote Originally Posted by reformed roadie
    Don't know where to start...

    The float fluid in the air chamber is simply for lubrication of the piston seals. It is not performing the same function as shock oil, so breakdown is less, if even an issue.
    It's doesn't effect damping, or performance.

    I would be more concerned about adding too much fluid, since the Fox is notorious for ramping up too quickly. A few cc's of excess fluid isn't going to help, considering the relative volume is pretty small. Your system doesn't seem so precise...more like inconsistant and wasteful.

    Why would you use shock oil? You even say that it may effect preformance and require a slight bit of tuning.
    How is all of that quicker than letting the air out, taking off the cap with a 26mm ratchet and turning upside down?

    The concept is much more useful for the rear shock.


    Wow...you're really hung up on the '99 Specialized ad campaign. You really need to get over it. I think my first post said I ditched the FSR for the superior blur XC.
    I got a laugh. Someone is hurt because the world of specialized was turned upside down on them. I also don't know where to start above. It appears you're posting to make yourself sort of try and sound smart. Hell, you're even saying one correct thing in order to prove me wrong, which is actually the basis for relubing an air chamber. That one is pretty good.

    I also didn't know Fox had only one fork, only one characteristic of spring curve. I also didn't know Fox was the only suspension manufacturer in existence.

    Oddly enough, you defended FSR, yet you're now on a VPP, which was actually noted for not having the best braking characteristics.

  34. #34
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    Quote Originally Posted by Jerk_Chicken
    I got a laugh. Someone is hurt because the world of specialized was turned upside down on them.
    What are you talking about? Really...get over the specialized thing.
    The point you fail to get is that it does make a difference whether the pivot is on the chain or the seat stay...nothing to do with specialized. While that is but one part of the overall design, it is a rather significant one.

    I'm not a Homer, but I am guessing that Dave switched pivot locations because he didn't want to pay you know who, not because it was better. Once Turner had his brand / following established, why pay for either the performance or 'sticker'.


    Quote Originally Posted by Jerk_Chicken
    I also don't know where to start above. It appears you're posting to make yourself sort of try and sound smart. Hell, you're even saying one correct thing in order to prove me wrong, which is actually the basis for relubing an air chamber. That one is pretty good.

    Oddly enough, you defended FSR, yet you're now on a VPP, which was actually noted for not having the best braking characteristics.
    Please...what is the basis for lubing the air chamber? If I am not losing any pressure, and the last two times I pulled my F100 apart it had about the full 5cc of float fluid I put in it...why I am doing you ridiculous, ass-backward thing with the pump? There are no moving parts within the chamber, it's simply lubing the piston seal.

  35. #35

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    What are you talking about? Really...get over the specialized thing.
    The point you fail to get is that it does make a difference whether the pivot is on the chain or the seat stay...nothing to do with specialized. While that is but one part of the overall design, it is a rather significant one.

    I'm not a Homer, but I am guessing that Dave switched pivot locations because he didn't want to pay you know who, not because it was better. Once Turner had his brand / following established, why pay for either the performance or 'sticker'.
    You'll have to march yourself over to the Turner forum to find out what went on there. The forum is just a few clicks away, so you are free to ask, or search.

    I counter that it's not a significant part anymore. Perhaps the three pivots about the rocker have more of an impact than one simple pivot location. You're not establishing why the horst link has so much importance, other than belief.


    Please...what is the basis for lubing the air chamber?
    In the course of time and usage, the oil becomes contaminated from rubber parts, composites, and metals sliding against one another, thus reducing the lubricity of the incredibly small amount of fluid in there. Some additives get used up during operation as well, further reducing the oil's ability to lubricate well.

    No moving parts?

    5cc's recovered? You won't be able to recover all 5 cc's in a measurable form, because that small amount of oil coats the inside of the chamber and generally has to be wiped out. Even removing the bath oil, for instance, on my 36's TALAS leg, with only 15cc in it, I was never able to recover that amount of oil, as it remained stuck to the walls of the interior. Some comes out if the fork is left to drain, but one will not recover all. If there's 150cc's, for instance, the margin will look a lot narrower, as the amount stuck to the interior parts is a smaller percentage of a larger number.

    You are also not speaking of the oil's color, or if it has particulate matter in it when it's removed. Additionally, the oil picks up water along the way, oxidizes, changes pH, and a host of other changes.

    Also, by your convention, there would never be a need to change the fluids in a fork.
    Last edited by Jerk_Chicken; 06-23-2009 at 09:28 AM.

  36. #36
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    Inside the air chamber, there are no moving parts...just air and a bit of fluid getting compressed by a piston.
    Any particulate contamination would have to go through the dust wipers/seals/oil ring to get in the fork, go down the outside of the stanchion, UP the inside of the stanchion wall and get past the piston seal, which is solid enough to hold tight 95psi...not buying it.
    I will guess (it's been a long time since I had physics) that heat generated from compressing a gas may play a role in it's breakdown, but I admit I am only guessing.

    I did not measure the 5ccs...but from what poured out, volume-wise it looked about the size of one pillow pack. Maybe 4 1/2+ . Close enough.


    Quite the contrary...I think it's a good idea to change fork oil after a short break in, than at regular intervals. Fork oil is doing a lot more, and is exposed to a lot more potential contaminants.

  37. #37

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Quote Originally Posted by reformed roadie
    Inside the air chamber, there are no moving parts...just air and a bit of fluid getting compressed by a piston.
    Any particulate contamination would have to go through the dust wipers/seals/oil ring to get in the fork, go down the outside of the stanchion, UP the inside of the stanchion wall and get past the piston seal, which is solid enough to hold tight 95psi...not buying it.
    I will guess (it's been a long time since I had physics) that heat generated from compressing a gas may play a role in it's breakdown, but I admit I am only guessing.

    I did not measure the 5ccs...but from what poured out, volume-wise it looked about the size of one pillow pack. Maybe 4 1/2+ . Close enough.


    Quite the contrary...I think it's a good idea to change fork oil after a short break in, than at regular intervals. Fork oil is doing a lot more, and is exposed to a lot more potential contaminants.
    I'll quote, bold, and just leave it as is. There's more, but the labyrinth explanation you gave shows painfully the point (or the origin of the particulate matter as explicitly stated) is escaping you.
    Then there's the contradiction of how you still think it's ok to change the fork oil.

  38. #38
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    Ok, I'll break this down so you understand my point:

    1. The float fluid is not breaking down fast enough that it needs to be replaced any more frequently than the fork oil, or better yet the seals.

    2. The method you propose for doing this job, which for some reason you see necessary (hey, knock yourself out...I'd rather be riding, drinking a beer or watching 'Family Guy'), is ridiculous for a fork.

  39. #39

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    1. The float fluid is not breaking down fast enough that it needs to be replaced any more frequently than the fork oil, or better yet the seals.
    Then ride harder.

  40. #40

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Hey reformed roadie,

    You also mentioned something about the pliers over the top cap. I knew there was a discussion we had previously about it, and the particular tool I used, so here it is for you to go through:

    http://forums.mtbr.com/showthread.ph...ghlight=knipex

    ...so you understand not all tools are created equal, including the ones you don't know exist.

  41. #41
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    uh...how is, what us essentially a pair of Channel locks, a more appropriate tool than a 26mm socket, that costs $5?

    I guess that is that same logic that uses a shock pump and a valve core tool to add fluid to an air chamber.


    Thanks for the time, though

  42. #42

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Again, it looks like you like looking at the pretty pictures, but you don't read anything. I'd like to see how you would remove the topcap with a 26mm. The answer might be contained in the pics. Maybe in the text. And yes, I do have a 26mm socket. A bunch of them, in fact.

    Oh yeah, you still haven't addressed the last posting about the air chambers not having any moving parts, either.

  43. #43
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    well...I let the air out of the air chamber. I attached the socket to my ratchet...put it on the top cap and turned counter clockwise.

    was that simple enough for you?

    Congratulations on your socket collection.

    I don't know what the deal is w/ the Zoke...I have a couple of 32 Fox forks.
    it has 26mm flats...I think it is even listed as tools required for servicing on the Fox site.


    RE: the air chamber. I am talking about the space inside the stanchion, above the piston, below the top cap that contains the air, which serves as the spring...INSIDE the air chamber / air spring, there are no moving parts. Yes, the piston moves and compresses the contents of the chamber, but I am not considering that as a moving part. my arguement is that the float fluid is not being mechanically broken down. Neither the pressure, nor heat is significant enough to do so.

    If you pumped up the air pressure to whatever the max pressure reached during operation - bottoming out - and left it there, do you think the fluid would break down? (hint: the fluid doesn't actually compress)


    Anyway...the argument is that the float fluid in the air chamber is not breakdown faster than either the fork oil or the seals, and does not need to be changed any more frequently. If you rode harder / faster / longer, you'd want to service your fork more frequently...at which point you'd change everything, right.
    So, your little DIY is not only bass-ackward, it's totally unnecessary.
    Last edited by reformed roadie; 06-24-2009 at 01:36 PM.

  44. #44

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    I don't know what the deal is w/ the Zoke
    Rock on.

  45. #45
    mtbr member
    Reputation: reformed roadie's Avatar
    Join Date
    Mar 2008
    Posts
    1,586
    The discussion here was re: the air chamber in a Fox float fork.

    I generally only care about working on the stuff I own...I don't work at a bike shop.
    Based on the forums and reviews, I don't feel I am missing anything w/ a fox compared to a zoke.

    Since this thread has been so ridiculously hijacked already - what is your view on the Enduro seals? I've heard mixed stuff from different sources...often the positive has come from people who sell them. Your thoughts?

  46. #46

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    The discussion here was re: the air chamber in a Fox float fork.
    Actually, it was "VPP vs. Horst/FSR"

  47. #47
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    5,036
    Annnnnnnd where back from our regular scheduled threadjack. Now back to "VPP vs. Horste/FSR" discussion already in progress.

  48. #48
    mtbr member
    Reputation: cort's Avatar
    Join Date
    Mar 2004
    Posts
    893
    We should rename this thread as "Jerk vs the Roadie"

  49. #49

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Roadie vs. Jerk. I'm out. He got his point across, hrmph hrmph...

  50. #50
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    5,036
    Annnnnd Jerk bows out, which makes Roadie the winner!

  51. #51
    mtbr member
    Reputation: cort's Avatar
    Join Date
    Mar 2004
    Posts
    893
    Yes... Ladies and Gents we have a winner. Better luck next match Jerk!

  52. #52

    Reputation:
    Join Date
    Oct 2005
    Posts
    16,457
    Oh hell. However, we might be the winners in the long term, knowing air chambers have moving parts in them and the oil has a finite usable life...

Members who have read this thread: 0

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2020 VerticalScope Inc. All rights reserved.