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  1. #1
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    Single-pivot linkage, why?

    I've been reading about shock linkage lately, and it seems like the Jekyll's single-pivot linkage is not the best design. I have an 02 Jekyll and before I got the rear shock pushed, the pedal bob was terrible. Now it's much better, but I look at four-bar linkage (Turner, Ellsworth), and it just looks so much more efficient, but there MUST be some advantage to the single-pivot design, right?

  2. #2
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    Absolutely...

    Quote Originally Posted by dulyebr
    I've been reading about shock linkage lately, and it seems like the Jekyll's single-pivot linkage is not the best design. I have an 02 Jekyll and before I got the rear shock pushed, the pedal bob was terrible. Now it's much better, but I look at four-bar linkage (Turner, Ellsworth), and it just looks so much more efficient, but there MUST be some advantage to the single-pivot design, right?
    lighter weight, less maintenance, and generally better lateral stiffness, especially with wear/age. And with the new "platform" type shocks the pedal bob problem is a thing of the past.
    "The question before the human race is, whether the God of nature shall govern the world by his own laws, or whether priests and kings shall rule by fictitious miracles."
    John Adams to Thomas Jefferson, 1815

  3. #3
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    Quote Originally Posted by jcw
    lighter weight, less maintenance, and generally better lateral stiffness, especially with wear/age. And with the new "platform" type shocks the pedal bob problem is a thing of the past.
    Although I agree with jcw, I don’t know enough about axle paths, ‘instant centers’, virtual pivot points and pivot locations to fill a small thimble, but I know what I like and I like my bike. That’s good enough for me.

    There are lots of very good choices out there. I strongly encourage anyone to try ‘em all and then ride what YOU like.

  4. #4
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    Nothing wrong with single pivot rear suspensions.... coupled with a SPV/Propedal shock, of course.


    Quote Originally Posted by jeffj
    Although I agree with jcw, I don’t know enough about axle paths, ‘instant centers’, virtual pivot points and pivot locations to fill a small thimble, but I know what I like and I like my bike. That’s good enough for me.

    There are lots of very good choices out there. I strongly encourage anyone to try ‘em all and then ride what YOU like.

  5. #5
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    Quote Originally Posted by funboarder1971
    Nothing wrong with single pivot rear suspensions.... coupled with a SPV/Propedal shock, of course.
    That's why I put a Swinger 4 Way Air on my Super V.

  6. #6
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    Sweet!

    I wish someone made a replacement shock for my Super V!

    Quote Originally Posted by jeffj
    That's why I put a Swinger 4 Way Air on my Super V.

  7. #7
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    From an engineering point fo view a Single pivot is a better design irrespective of the disadvantages to pedalling induced bob.

    With a 4 bar link all the drivetrain and suspension forces go through tiny little bearings which is not a good solution even though it feels good on the trail.

    Single pivots distribute the drive train forces into the chainstays and the main pivot bearings which are much bigger.
    This results in less maintenance.

    Many DH bikes still use single pivots effectively with no oss of performance.

    Stable platform shocks have brought single pivot bikes back in line with anything else out there.

    Personally I prefer single pivots simply because they are stronger.

  8. #8
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    Quote Originally Posted by Brad
    From an engineering point fo view a Single pivot is a better design irrespective of the disadvantages to pedalling induced bob.

    With a 4 bar link all the drivetrain and suspension forces go through tiny little bearings which is not a good solution even though it feels good on the trail.

    Single pivots distribute the drive train forces into the chainstays and the main pivot bearings which are much bigger.
    This results in less maintenance.

    Many DH bikes still use single pivots effectively with no oss of performance.

    Stable platform shocks have brought single pivot bikes back in line with anything else out there.

    Personally I prefer single pivots simply because they are stronger.
    sorry brad have to disagree with you here buddy on the bearing issue the majority of four bar bikes do have smaller bearings but if for example you took the load capacity and calculate the actual surface area for the given load you will find the four bar bike has a higher load capacity

    however the design of all the housings and intricacies of engineering multiple pivot suspension systems mean that more material is used and hence an increase in weight
    added to that is the maintenance of up to 8 bearings instead of two and the wear of all these little bearings can lead to quite a bit of slack in the system

    the four bar was supposed to be the all singing all dancing suspension design which solved a several simple problems

    platform shocks however moved the clever thinking and positioning of pivots rotational centres and load paths to a unit which could theoretically cancel out a large proportion of
    associated design errors

    platform shocks are beginning to do what what the moto x shock revamp did in the 70s and 80s to remove the mass moving parts and inneficiencies of a badly designed multi link system

  9. #9
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    Quote Originally Posted by mikedesign
    sorry brad have to disagree with you here buddy on the bearing issue the majority of four bar bikes do have smaller bearings but if for example you took the load capacity and calculate the actual surface area for the given load you will find the four bar bike has a higher load capacity

    however the design of all the housings and intricacies of engineering multiple pivot suspension systems mean that more material is used and hence an increase in weight
    added to that is the maintenance of up to 8 bearings instead of two and the wear of all these little bearings can lead to quite a bit of slack in the system

    the four bar was supposed to be the all singing all dancing suspension design which solved a several simple problems

    platform shocks however moved the clever thinking and positioning of pivots rotational centres and load paths to a unit which could theoretically cancel out a large proportion of
    associated design errors

    platform shocks are beginning to do what what the moto x shock revamp did in the 70s and 80s to remove the mass moving parts and inneficiencies of a badly designed multi link system

    No problem disagreeing Mike and I do understand that 4 bar would have a higher load capacity in theory.
    However when a bearing is resisting drivetrain as well as suspension loads, it is operating at a much high capacity due to the direction of the forces acting on the bearing.. This copupled to often misalignment of suspension components means that 4 bar designs are often placing more stress on the bearing than a single pivot would.

    Also the future seems to be internal hubs of gearboxes mounted in the BB area of the frame. This new technology I think will sound the death bell for multi link suspensions. Single pivots with stable platform shocks are the future abnd will be far cheaper to manufacture and maintain that current multi link units

  10. #10
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    Quote Originally Posted by Brad
    No problem disagreeing Mike and I do understand that 4 bar would have a higher load capacity in theory.
    However when a bearing is resisting drivetrain as well as suspension loads, it is operating at a much high capacity due to the direction of the forces acting on the bearing.. This copupled to often misalignment of suspension components means that 4 bar designs are often placing more stress on the bearing than a single pivot would.

    Also the future seems to be internal hubs of gearboxes mounted in the BB area of the frame. This new technology I think will sound the death bell for multi link suspensions. Single pivots with stable platform shocks are the future abnd will be far cheaper to manufacture and maintain that current multi link units
    granted for the most part i see your point


    it might seem like im being a bit nitpicky here probably beecause i fall into the fan of four bar link when it is actually engineered properly

    recently ive been working on a design for a uk company here

    http://www.edgebikes.com/ebnews.html

    have a look and see what you thinkitsdifferent but it seemsto work quite well

    last year they sold quite a few frames and won quite a few races the conditions here a quite harsh and you cant really design a product without that in mind

    we use a much larger bearing 17x30x8 8 bearings per bike, its a special to take axial and radial loads and the fact that the back end just floats off the back on these bearingwhich means that it was designed with the above points you made in mind

    i think a lot of companies try to get away with what you could consider to be does the job type engineering, bushes and the like are not really a long term solution
    next year to save weight the switch to needle roller and thrust bearings will be made namely to save weight a to eliminate the problem of overloading

    its probably a european thing but

    completely agree with you on the death of multi link
    when gearbox does come of age ,our next bike has this goal purely in mind single pivot with the gearbox inside the large diameter pivot

    i did a short spell atGT in 96 when they showed the g box bike and was quite surprised when it showed up at a bike show in london in 2003 nearly unchanged just shows that people werent ready for thes kinds of ideas back then

  11. #11
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    Single pivot linkage

    Ventana said for stiffness, Trek, Cdale, Castelano,and other softail builders say weight and reliability. In reality I think it has more to do with differentiating the product and not riding Horst Lighteners( and FSR) coatails. Most of the well built bikes out there can be made to ride well. I have noticed that of the single pivot bikes I've owned the further the pivot is from the BB the harder it is on the drivetrain due to chain growth. Othrwise there still fun.

  12. #12
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    Quote Originally Posted by mikedesign
    granted for the most part i see your point


    it might seem like im being a bit nitpicky here probably beecause i fall into the fan of four bar link when it is actually engineered properly

    recently ive been working on a design for a uk company here

    http://www.edgebikes.com/ebnews.html

    have a look and see what you thinkitsdifferent but it seemsto work quite well

    last year they sold quite a few frames and won quite a few races the conditions here a quite harsh and you cant really design a product without that in mind

    we use a much larger bearing 17x30x8 8 bearings per bike, its a special to take axial and radial loads and the fact that the back end just floats off the back on these bearingwhich means that it was designed with the above points you made in mind

    i think a lot of companies try to get away with what you could consider to be does the job type engineering, bushes and the like are not really a long term solution
    next year to save weight the switch to needle roller and thrust bearings will be made namely to save weight a to eliminate the problem of overloading

    its probably a european thing but

    completely agree with you on the death of multi link
    when gearbox does come of age ,our next bike has this goal purely in mind single pivot with the gearbox inside the large diameter pivot

    i did a short spell atGT in 96 when they showed the g box bike and was quite surprised when it showed up at a bike show in london in 2003 nearly unchanged just shows that people werent ready for thes kinds of ideas back then

    I agree with your design principals Mike. using preloadable bearings sorts a lot of the probelms out although they are pricier it is the better solution.

    Ialso agree 100% with your design philosophy that the wheel path should affect chain length and I guess this is where a 4 bar has an advantage. It's easier to tune the wheel path to achieve this with a 4 bar system than with a single pivot.
    I've seen your bikes in the UK and really like them especially since you guy's have not fallen for all the excessive tube shpe manipulation game. Simple basic engineering no nonsense, the way it should be.

  13. #13
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    Quote Originally Posted by Brad
    I agree with your design principals Mike. using preloadable bearings sorts a lot of the probelms out although they are pricier it is the better solution.

    Ialso agree 100% with your design philosophy that the wheel path should affect chain length and I guess this is where a 4 bar has an advantage. It's easier to tune the wheel path to achieve this with a 4 bar system than with a single pivot.
    I've seen your bikes in the UK and really like them especially since you guy's have not fallen for all the excessive tube shpe manipulation game. Simple basic engineering no nonsense, the way it should be.
    thanks for that brad


    ill take you advice about tube manipulation on board because ikind of hadit in my mind to start doing that kind of thing on the free ride and downhill

    the plan was to use some monocoque sections but if simpleris the preffered option maybe youre right the manufacturingis a bit of a headache when it comes to pressing sheet metal

  14. #14
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    Quote Originally Posted by mikedesign
    thanks for that brad


    ill take you advice about tube manipulation on board because ikind of hadit in my mind to start doing that kind of thing on the free ride and downhill

    the plan was to use some monocoque sections but if simpleris the preffered option maybe youre right the manufacturingis a bit of a headache when it comes to pressing sheet metal

    If the pressed sheet metal gives a measurable advantage then it should be pursued and perhaps implemented.

    ALl I'm saying is that in the marketing game, manufacturers are trying desparately hard to differentiate their bikes by using tube shape manipulation where it's not needed.
    In some cases the engineering is based on sound reasoning but in most it's merely a gimmick to have the customer looking at the bike longer. The longer you hold his attention the easier it becomes to sell the product.

    Not going down this route is also an optional strategy to follow which In my mind carries a lot of weight and shold be respected. This is why cannondale is a brand I respect because most of the engineering is a solution to a problem not a gimmick. Some of the solutions are out of the box ie Lefty.

    what I like about edgeBikes is the back to basics no nonsense engineering in the bikes. Perhaps Frame shape is valid area to ertain attention but there's loads of people out who aren't phased by the mumbo jumbo and just want performance.

    I'm one of them

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