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Thread: VPP vs DW-Link

  1. #1
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    VPP vs DW-Link

    Aight - This may be a dumb question, but what is the difference between a VPP linkage and the DW-Link?

    Things have been a bit quiet around here, and I was just wondering. Looking more for the layperson explanation rather than the engineer explanation. They look awfully similar, no?

  2. #2
    The Ancient One
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    They don't really look that similar when you get the suspension moving. The two short links that connect the front triangle to the rear triangle rotate in opposite directions to each other on the VPP. They rotate in the same direction on the DW-link.
    "Don't criticize what you can't understand."

  3. #3
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    DW-link, VPP, Horst-link and Full floater

    Trek try to explain the new Full Floater and compare it to DW-link, VPP and Horst-link in this not entirely hype free blog: http://trekmountain.typepad.com/king...loater-ex.html

    Trek make som some pretty interesting propositions:

    The Ibis Mojo with DW-Link and VPP bikes fall victim to their very small links – they simply cannot provide the control needed due to the dramatic swing amount and radius it covers during use. But t.hey differ slightly in effect as follows:

    Mojo with DW-Link – This curve has a pretty steep progressive rate initially that flattens out in mid stroke and quickly goes to a digressive rate for the last half of its travel. This curve makes it almost impossible to optimize the tuning of the shock as the first part of the curve requires that the shock have light spring force and damping but the second part of the stroke requires the opposite. If you set this system up to have decent small bump performance, it will blow through its travel, giving the bike a wallow feel and will bottom out easily. It is almost impossible to optimize the shock tuning to this curve due to its contradicting requirements and huge swing.

    I'll really appreciate it if Dave and Derby comment on this.

  4. #4
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    Quote Originally Posted by runermm
    Trek try to explain the new Full Floater and compare it to DW-link, VPP and Horst-link in this not entirely hype free blog: http://trekmountain.typepad.com/king...loater-ex.html

    Trek make som some pretty interesting propositions:

    The Ibis Mojo with DW-Link and VPP bikes fall victim to their very small links – they simply cannot provide the control needed due to the dramatic swing amount and radius it covers during use. But t.hey differ slightly in effect as follows:

    Mojo with DW-Link – This curve has a pretty steep progressive rate initially that flattens out in mid stroke and quickly goes to a digressive rate for the last half of its travel. This curve makes it almost impossible to optimize the tuning of the shock as the first part of the curve requires that the shock have light spring force and damping but the second part of the stroke requires the opposite. If you set this system up to have decent small bump performance, it will blow through its travel, giving the bike a wallow feel and will bottom out easily. It is almost impossible to optimize the shock tuning to this curve due to its contradicting requirements and huge swing.

    I'll really appreciate it if Dave and Derby comment on this.
    Trek’s analysis of the dw-Link is most likely naïvely mistaken, or possibly sadly purposeful lies, with only a glimmer of fact. Only the sentence about the Mojo’s curve rate change is fairly true: “Mojo with DW-Link – This curve has a pretty steep progressive rate initially that flattens out in mid stroke and quickly goes to a digressive rate for the last half of its travel.”

    The Mojo’s dw-Link (and Iron Horse Azure and Mkiii) are designed for exponentially rising rate springs such as the Fox RP23’s air spring rate. Which is gradually rising in progressive rate of resistance to compression through about ¾ travel then ramps up very rapidly in rising rate during the deepest ¼ of travel.

    This deep travel very rapid rising air-spring rate is offset by the Mojo’s dw-link leverage than relaxes in progression of rate into digression or falling rate so that there is leverage enough to compress the very rapidly rising resistance of the spring.

    The effect of the RP23 spring rate, plus the rising suspension leverage that transitions deeper in travel to linear and slightly falling near bottom travel, combines to produce an ideal net progressive wheel travel leverage rate, which is most desirable for rear suspension.

    Damping can be tuned with a dw-Link normally, even ideally just for handling and feel. Using high-speed compression for adjusting mid travel compliance for bigger bumps and fast downhill speeds from soft to firm (the RP23 high-speed compression is set moderate to very firm internally with no external adjustment). And low speed rebound and low speed compression (propedal) to settle bump induced wallow. And some riders firm up low speed compression (propedal) to produce a platform effect for less compliant suspension for eliminating the minimal standing pedaling bob and for more noticeable feedback from the trail surface.

    The only problem with the Mojo’s linkage curve is when using linear springs such as coil (as I use for more custom fine tuning control and better small bump smoothness). The deep travel linkage leverage cure is not well balanced for bottom out resistance without a very rising rate spring. I’ve had my coil shock, a Fox Vanilla RC, custom rebuilt and tuned by PUSH Industries to have more deep travel spring resistance using a bigger more progressive elastomer bump stop. And the PUSH tune has more adjustment range of compression damping than stock to add some damping firmness without becoming spiky and harsh hitting bumps.

    Interestingly the Iron Horse 6 Point 6.3 inch travel all mountain rear suspension is speced with a rising rate air shock, a custom OEM soft compression damped Fox DHX-Air with 2.5 inch stroke. But the 6 Point suspension is also designed to accept a .25 inch longer coil shock with the same mounting dimension to have the same 7 inch rear travel as their heavy duty 7 Point freeride extreme jump bike. The extra length of the stroke provides the distance a linear coil spring needs to stop compressing before bottom out compared to the shorter distance a rising rate air spring needs, when using about the same sag. I’m not sure but the travel gain indicates the linkage curve leverage is not as digressive in deep travel as shorter travel air spring designs such as the Mojo’s.

  5. #5
    Church of the Wheel
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    Sooo...what's the difference between the VPP and the DW-Link?

  6. #6
    It's the axle
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    A couple of Googles gave this-

    I personally find this stuff BORING. But here you go-

    http://spokesmanbicycles.com/page.cfm?pageID=159

    http://en.wikipedia.org/wiki/Bicycle_suspension

  7. #7
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    Thank you, but neither of these answer the question. Neither even mentions the DW-Link. I know there are savvy engineer-types out there who truly understand the difference between VPP & DW Link (Hans, DW, and surely others). Can someone give a brief, as-non-technical-as-possible version?

    Oops - I'm a tard. Didn't read second reference carefully enough - it does talk about DW-Link. But the article lumps VPP and DW-Link together, and fails to discuss their differences. Obviously there are differences, otherwise they wouldn't have different patents, right?

  8. #8
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    Quote Originally Posted by mtb143
    Aight - This may be a dumb question, but what is the difference between a VPP linkage and the DW-Link?

    Things have been a bit quiet around here, and I was just wondering. Looking more for the layperson explanation rather than the engineer explanation. They look awfully similar, no?
    Dw-Link has a different axle path and wheel leverage rate than trademarked VPP.

    The ride time results are that both VPP and dw-Link produce almost no pedal bob when seated. - But the similarity ends there.

    The dw-Link doesn’t resist bump compliance, while VPP stiffens more the harder you pedal. VPP actually raises and extends the suspension when standing and pedaling in the small and middle rings, and has a pedaling cadence stalling effect when pedaling in larger bumps. There is no such pedal stalling or suspension extending effects from the dw-Link in the same hard pedaling situations.

    VPP breaks traction on loose climbs rather easily, much like a hardtail, while the dw-Link maintains the most efficient acceleration traction compared to other designs, whether the trail is smooth, bumpy, or jagged.

    The dw-Link remains at maximum possible activity and handling control when braking, while VPP stiffens and skids easily out of control.

    VPP acts almost completely opposite dw-Link. There are no downsides or trade-offs of the dw-Link compared to other suspension systems, while VPP trades having a firm pedaling platform for losses in traction and bump compliance while pedaling and braking.

  9. #9
    Trail Rider
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    My four finalists were The Intense 5.5 FRO, Ibis Mojo, Blur LT and the MK III.
    My buddy had a Blur and my other buddy, a MKIII. I got to spend some time on both.
    I noticed right away the Blur leaned more towards a HT(sporty feel), but it absorbed bumps seamlessly like they weren't there. I really liked it. It seemed less active DH than my Tracer, when braking. I had read that it didn't perform as well as far as loose climbs. I didn't notice this. It was less active than my old bike. It did real well on out of saddle climbs, much better than my Tracer.

    My experience on the MKIII was even better. It was totally active when climbing and descending when braking. It didn't bob like my old bike did. The suspension felt just right for me. I rode it a few times and tried all different climbs. I was impressed by it's traction when climbing in technical terrain.

    Now if I preferred a more HT sporty feel, I would have gone with the Intense. My other buddy bought a 5.5. I rode that, and I enjoyed it. I couldn't find any MKIII frames, so it was down to the Mojo and the 5.5 FRO. I chose the Mojo. I did have some setup problems with the RP23 and the Talas had to go back to Fox. I was experiencing a lot of pedal hits in rocky terrain. It seems like the suspension was blowing through its mid travel. A high volume sleeve solved this. Heavier riders need a more linear shock and the RP23 still doesn't bottom out. Now it performed as well as the IH MK III with a little more travel and lighter. I took it out today without one pedal hit in some rocky climbs.

    I probably would have been happy on the VPP, but I preferred the feel of the DW bike.
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  10. #10
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    Okay, so the short answer is that VPP and DW-Link are mechanically similar, using two linkages to define a wheelpath, but they differ in the exact wheel path and the "wheel leverage rate", yes?

    What exactly is covered in the different patents? The wheelpath? And what is it about the DW wheelpath that makes it superior to the VPP wheelpath?

    ...Just trying to understand some of the science underneath the magic that is the Mojo.

  11. #11
    _dw
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    OK, I don't have a lot of time to get into this, but I believe I answered this question for a poster with the handle "le buzz" sometime in the last few months, maybe in the Iron Horse board. You can use the search function to find info.

    dw-link and VPP could not be more different suspension systems. The fact that they both use short links is about the only real similarity.

    dw-link's is the worlds first and only design focusing on position sensitve anti squat. The patents talk about this in detail, 7128329 should be a good read for you. Anti-squat is an essential and often misunderstood aspect of all suspension vehicles. The Trek thing that you mention is a great example of how misunderstood the concept really is. The proper application of anti squat balances out the effects of mass transfer on the suspension during acceleration, and is the only way to free up the suspension to absorb the smallest of bumps. Adding excessive low speed compression damping is not the same, and also a quick way to lose traction in the bumps, both under power and coasting. dw-link develops more anti squat early travel, a realtively constant amount through the middle of the travel, and less in the end of the travel. This coincides with the wheel rate designed into the bike, which is designed for maximum compliance even early in the travel. VPP on the other hand starts off with pro squat (the suspension actually takes your energy and physically compresses the suspension), then by mid travel gets into developing anti squat. The VPP bikes typically use a leverage rate that is very low in the initial travle, then regresses to mid travel. THis increases damper shaft velocity early travel, effectively adding spring rate and damping in the beginning of the travel. Also, a hefty dose of compression damping helps to keep things in check. Like most other bikes that use similar strrategies, you can pedal great on a fireroad, but once you get into the rough stuff at the edges of traction, the traction deficiency begins to become apparent.

    Leverage rate, just want to touch on this for one second before I have to run. There is no other suspension architecture that I know of that can achieve a wider range of leverage rates than the dw-link layout. The bikes that have been built and sold are a testament to that. Why Trek would try to misinform the public with the things that they have written is beyond me. When I sent them actual graphs of production bikes to prove the point, they changed their typepad to say "Mojo" instead of all dw-links. Maybe I should get my own "blog" to set things straight..

    hmmm.
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  12. #12
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    Thank you, sir.

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