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  1. #1
    swag ho Administrator
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    Felt Equilink revealed...

    . Well not yet but I've taken it on a few rides and now I'm taking the suspension apart to analyze it. I'm learning a few things.

    Any ideas on how I should bench test it? As you can see, I'm taking pieces out to isolate their role in the system. Suggestions?

    Obviously, I'm going to take it out on a bunch of rides. But there might be something to be learned by tinkering in the garage too.

    francois
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  2. #2
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    I don't think there is a lot you can do to isolate the various parts and their roles in the suspension behavior. Without the link connected the lower linkage is free to rotate around the pivot on the back of the BB and the wheelbase of the bike will be free to extend and compress as you pedal and brake.

  3. #3
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    I'd be careful about what you do there, since there is no pivot at the dropout, removing the red link (and shock) allows the upper and lower rockers to counter rotate under the weight of the bike, spreading apart the seat and chain stay - and it doesn't take much to push them past their elastic limit can cause permanent damage. There is a reason the red link is there - it limits this motion.

  4. #4
    Not just famous; infamous
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    Axle path map?

    What I'd like to see is an actual axle path. Could you maybe put a pen thru the dropouts and show us what the axle path looks like? Don't know what other steeds are in your stable, but it'd be really nice to compare it to other bikes' axle paths. (VPP, single pivot, short link, etc.)

  5. #5
    Amphibious Technologies
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    Quote Originally Posted by itsdoable
    I'd be careful about what you do there, since there is no pivot at the dropout, removing the red link (and shock) allows the upper and lower rockers to counter rotate under the weight of the bike, spreading apart the seat and chain stay - and it doesn't take much to push them past their elastic limit can cause permanent damage. There is a reason the red link is there - it limits this motion.
    If you remove the red link, it will essentially be like a DW link with a differect IC but a DW-like linkage, in any case. My uninformed guess is, that red link is a design around the DW link. Though the absence of a rear triangle will cause what you describe.
    "The best you've ridden is the best you know" - Paul Thede, Race Tech

  6. #6
    conjoinicorned
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    My uninformed guess is, that red link is a design around the DW link.
    that's an extremely uninformed guess.

    DW did NOT invent parallel linkage, therefore it is NOT a copy of the actual DW link.
    what would rainbow unicorn do?

  7. #7
    swag ho Administrator
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    Quote Originally Posted by itsdoable
    I'd be careful about what you do there, since there is no pivot at the dropout, removing the red link (and shock) allows the upper and lower rockers to counter rotate under the weight of the bike, spreading apart the seat and chain stay - and it doesn't take much to push them past their elastic limit can cause permanent damage. There is a reason the red link is there - it limits this motion.
    I hear ya. Just fyi, I'm not going to ride it like this. I'm just disconnecting it to understand what it does.

    I've learned a little bit already. Just removing the shock and seeing the travel path and action is interesting. Then seeing how the pedal load affects the suspension is interesting too. I'll take some videos later.

    fc
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  8. #8
    Amphibious Technologies
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    Quote Originally Posted by ferday
    that's an extremely uninformed guess.

    DW did NOT invent parallel linkage, therefore it is NOT a copy of the actual DW link.
    Perhaps but your argument is illogical or fallacious (non sequitur to be specific).

    Wasn't it Earl MacPherson then adopted by Horst Leitner for bicycles then designed around by other bike manufacturers?

    You should read my post carefully. I DID NOT say it is a copy; I said it's DW-like; there's a diference. But for argument's sake, let's assume DW did not invent the parallel linkage, which he evidently did not, it certainly does not mean the Equilink minus the "red link" and assuming a similar resulting IC is not DW-like in function; now does it?
    Last edited by SCUBAPRO; 02-02-2007 at 11:46 AM.
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  9. #9
    swag ho Administrator
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    Quote Originally Posted by coolhandluchs
    What I'd like to see is an actual axle path. Could you maybe put a pen thru the dropouts and show us what the axle path looks like? Don't know what other steeds are in your stable, but it'd be really nice to compare it to other bikes' axle paths. (VPP, single pivot, short link, etc.)
    I'll take a video of the axle path. There's a ton of horses on the stable. I just need a lot of beer to entertain me while wrenching.

    fc
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  10. #10
    Amphibious Technologies
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    Quote Originally Posted by francois
    I'll take a video of the axle path. There's a ton of horses on the stable. I just need a lot of beer to entertain me while wrenching.

    fc
    fc, my sincere apologies for the slight derailment. I too am interested in what you come up with. Thanks, in advance, for the info.
    "The best you've ridden is the best you know" - Paul Thede, Race Tech

  11. #11
    mtbr member
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    Quote Originally Posted by francois
    Any ideas on how I should bench test it? As you can see, I'm taking pieces out to isolate their role in the system. Suggestions?
    I for one would love it if you would remove the rear shock and go for a long, technical downhill ride.

  12. #12
    MK_
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    Quote Originally Posted by francois
    As you can see, I'm taking pieces out to isolate their role in the system. Suggestions?
    You can safely bolt the shock back on, isolating it out of the system would make it impossible to ride test. And we all know how those work, anyhow.

    Seriously, however, it would be interesting to add to coolhandluchs' idea of the pen in the dropout and to plot the axle path without the red link bolted in. Comparing it to a DW linkage bike would reveal whether Scuba's suspisions are grounded.

    _MK
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  13. #13
    the 36 year old grom
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    I would be interested in what the spring rate of the flex pivot in situ. The design is over constrained ( 6 pivots) so it has to flex at the stay(designed to flex). which is why it may look like DW but I realy think it is a different animal.

    so you could take the shock off and use a fish scale to pull the wheel up thru its travel. would interest me to see the spring curve. probably too hard for you to do with out a jig of some sort.

  14. #14
    mtbr member
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    a few more pics of the Virtue 2


    no trail time in yet as we've got a little too much snow. The manufacturing is tight However, the first thing i noticed down at the chainstay yoke was the very tight toleraces between moving links. So tight that it has NO dirt or mud shedding abilities. My fear is that a rock or pebble can get logged and actually do damage.

    We'll see once we get her in the dirt.



    later, Chad
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  15. #15
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    Quote Originally Posted by SCUBAPRO
    Perhaps but your argument is illogical or fallacious (non sequitur to be specific).

    Wasn't it Earl MacPherson then adopted by Horst Leitner for bicycles then designed around by other bike manufacturers?

    You should read my post carefully. I DID NOT say it is a copy; I said it's DW-like; there's a diference. But for argument's sake, let's assume DW did not invent the parallel linkage, which he evidently did not, it certainly does not mean the Equilink minus the "red link" and assuming a similar resulting IC is not DW-like in function; now does it?
    Try this animation of a a 6-bar design. You can click and drag the pivot points around to change dimentions.

    http://www.igorion.com/_hf_files/_st...tephenson.html

    There was quite a look in the MTBR Interbike threads at the Felt path and it turns out to be more round and long radius within the travel range, more FSR like, than the dw-Link's more elliptically shorter to longer radius shaped path.

    DW may have borrowed the cantilevered type dropout from earlier parallel link design, but dw-Link is not a parallel link design, actually 70 - 90 degree away from parallel, and doesn't ride at all like one. (Yes, I've ridden the parallel link design Rocket-88 too, not very impressive other than for short travel sprint racer use).

    There are many designs now obviously closely following the dw-Link invention, but the Equilink is probably not one of them.

  16. #16
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    Quote Originally Posted by derby
    Try this animation of a a 6-bar design. You can click and drag the pivot points around to change dimentions.

    http://www.igorion.com/_hf_files/_st...tephenson.html
    Nice

    I have a question about the chainstay / seatstay connection near the dropout in the Equilink - is it rigid? If no and assuming there is no significant flex on the chainstay or seatstay I can see only two reasons they put red link there:
    1) durability,
    2) marketing/ patent issues.

    Sorry.

    Quote Originally Posted by derby
    DW may have borrowed the cantilevered type dropout from earlier parallel link design, but dw-Link is not a parallel link design,
    What do you mean by "parallel link design"? Parallel upper and bottom linkages? Imho it is not so important unless both links have the same length. In the later case we got a straight line axle path.

    I do not say it is DW-link copy but imo it is another Outland-like design.

    Cheers
    marcin

    PS. My English is not fluent but I hope it is good enough.
    PS. 2. This is my first post here so Hi everybody!

  17. #17
    The Ancient One
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    What the path should look like

    The picture below comes from my playing around with a Stephenson 6-bar linkage program. The pivot positions are not perfect but pretty close. The red line between the left hand red dot and the point of the black angle above it would be the Felt axle path approximately.

    In real life the path should be slightly more rearward. But this diagram shows how straight it is--straighter than any other design I think.

    The thing that sets the Equilink apart from other linkages is that you can't calculate the anti-squat from simply knowing the axle path. The red link acts to short circuit the transmission of forces from axle to frame so that the bike has much more accelerational anti-squat than the axle path angle would indicate.

    The design will pretty much eliminate squat from acceleration but does very little to reduce squat from rider bounce. Some riders will like this; some will not.
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  18. #18
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    Quote Originally Posted by Marcin J.
    What do you mean by "parallel link design"? Parallel upper and bottom linkages? Imho it is not so important unless both links have the same length. In the later case we got a straight line axle path.
    oops, my mistake - I mixed IC with CC. Radius of the rear axle path will be equal to the length of these links.

    Cheers
    marcin

  19. #19
    www.derbyrims.com
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    Quote Originally Posted by Steve from JH
    The picture below comes from my playing around with a Stephenson 6-bar linkage program. The pivot positions are not perfect but pretty close. The red line between the left hand red dot and the point of the black angle above it would be the Felt axle path approximately.

    In real life the path should be slightly more rearward. But this diagram shows how straight it is--straighter than any other design I think.

    The thing that sets the Equilink apart from other linkages is that you can't calculate the anti-squat from simply knowing the axle path. The red link acts to short circuit the transmission of forces from axle to frame so that the bike has much more accelerational anti-squat than the axle path angle would indicate.

    The design will pretty much eliminate squat from acceleration but does very little to reduce squat from rider bounce. Some riders will like this; some will not.
    I agree with your assessment. There is a mechanical bias between low and high leverage torque rates when combined in the same mechanism. A higher torque leverage will override the influence of low leverage rate. The Equilink designís cross-link has higher leverage torque during acceleration tension but a much lower leverage torque relation during bump activation.

    During pedal and acceleration there is more horizontal tension directed across the straighter aligned lower stay and lower frame link and so the cross-link would be a higher leverage factor binding the activity of the upper frame link against vertical movement. But vertical input from bumps or rider bob would direct leverage torque along the upper stay and upper frame link, and then the cross-link is in a low torque relation mainly keeping the system from collapsing and not binding the suspension so as when there is horizontal tension.

    Looking at Francoisís picture at the top with the shock and cross-link disconnect reveals the answer to the question I earlier had about spring rate. I had earlier thought there might be a falling rate spring tension from rather stiff flex stays. (falling rate springs or shock damping produces a pedaling platform effect). But it appears that the rear stays flex fairly easily so there would be very little spring rate influence within the travel range.

    So there is something special about the Equilink. I look forward to demo riding one hopefully at Sea Otter this April. Iím curious if low pedal bob comes at a cost of mush deadening pedal performance like platform shocks do for monopivots compared to the lively and snappier performance of a more purely path based high anti-squat suspension such as VPP and the exceptionally well balanced dw-Link. Iím expecting the Equilink pedaling is also very snappy when the shock has minimal platform damping.

  20. #20
    Chillin the Most
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    Quote Originally Posted by SCUBAPRO
    Wasn't it Earl MacPherson then adopted by Horst Leitner for bicycles then designed around by other bike manufacturers?
    Not wanting to get into a pissing match or even sure this is relevant info, but...Horst Leitner didn't actually design the Horst Link, it was Karl Nicolai that came up with the idea while he was working for Horst. Horst merely put into production Karl's design and everyone started calling it the Horst Link.

  21. #21
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    Check this out...

    Felt's inspiration?

  22. #22
    melon farmer
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    Kavik - I just read this too:

    http://thylacinecycles.com/wordpress/?p=50

    I felt a bit queasy afterward.

  23. #23
    TM1
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    I'm a little confused with this ...

    as far as I can tell, if you remove the red link you get a DW-link suspension. the same location of pivots and links.
    now, the DW-link do not have any flex in it when it comes to path movement. so the red link have NO part in the linkage or path.

    you can not say that the red link is responsible for the rotation of the links because they will rotate just the same without the red link.

    correct me if I'm wrong.

  24. #24
    The Ancient One
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    Quote Originally Posted by TM1
    as far as I can tell, if you remove the red link you get a DW-link suspension. the same location of pivots and links.
    now, the DW-link do not have any flex in it when it comes to path movement. so the red link have NO part in the linkage or path.

    you can not say that the red link is responsible for the rotation of the links because they will rotate just the same without the red link.

    correct me if I'm wrong.
    You're wrong.

    The two rear links, seatstay and chainstay, are carbon fiber and designed to flex. If you removed the red link, the mechanism would be unstable. The lower short link would be free to move without activating the shock as the rear stays flexed under the rider's weight or from hitting bumps.

    If you connect the red link the rear stays have to flex (or have an extra pivot as in the longer travel version) because the two rear pivots move apart and come together as the suspension cycles.

    If the rear end is rigid and there is no red link, then you do have a DW type linkage.
    "Don't criticize what you can't understand."

  25. #25
    Doesntplaywellwithmorons!
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    Steve and every other felt shill will of course conveniently continue to ignore the kavik evidence and the fact that felt blatantly ripped the design.
    I don't post to generate business for myself or make like I'm better than sliced bread

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