Please explain single Pivot vs. Specialized linkage- Mtbr.com
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  1. #1
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    New question here. Please explain single Pivot vs. Specialized linkage

    Have a Bullit, and am thinking of getting a Big Hit Expert (can get a decent price).

    For assumption purposes, let's say they both have the same rear shock (Avalanche).

    Can someone please explain the ride difference with the 2 different suspension designs?

    Will the Big Hit feel more active?

    I'm only used to the single pivot, so any info is appreciated.

    ....especially those who have ridden both.

  2. #2
    eci
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    i personally like both designs, but it all depends on how the shock is mounted. I am not a fan of the bullit and hecklers because when the shock compresses it feels like your moving at a direct angle down. Where as on my foes (fxr) it feels like the bike is compressing. It is really personal preference. I have an 02 SGS Dh and i love the way it feels with my avy on the back. take a few test rides and go from there

  3. #3
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    hmmmmm

    Quote Originally Posted by snowskilz
    i personally like both designs, but it all depends on how the shock is mounted. I am not a fan of the bullit and hecklers because when the shock compresses it feels like your moving at a direct angle down. Where as on my foes (fxr) it feels like the bike is compressing. It is really personal preference. I have an 02 SGS Dh and i love the way it feels with my avy on the back. take a few test rides and go from there
    Here is my $.02 for what it's worth. I can compare a heckler to an enduro. Braking over rocky stuff, the enduro wins, hands down. The horst link is way more active. There is actually a term for the single pivot braking action, that I'm sure someone on this board will know.
    I also worry a little about just one pivot taking all the abuse- drops, jumps etc. In the rock climbing world you are taught not to rely on a single piece. Of course the Bullit is so over built that it prolly isn't too much of an issue, but I have seen alot of bushings go on all sorts of frames.
    Who the hell knows. I don't know what I'm talking about.
    West coast hucker or Nate N will know.

  4. #4
    eci
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    the feeling under breaking for a single pivot is called brake jacking. but you can buy a floating rear brake from brake therapy to stop that. but id still go with the 4 bar linkage

  5. #5
    pdh
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    On the Titus web site they have a good page or two explaining different type of likage & etc.
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  6. #6
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    The main difference between the two is the path the rear wheel takes when the suspension is compressing. Single pivot designs tend to move the rear wheel in an arc as the suspension moves through it's travel. This in turn changes the length of the wheel base. It is this that cause things like brack jack and bio pacing when braking or pedaling respectively. Four bar link designs attempt to correct this problem. By having multiple pivots the rear wheel travels in a much straighter path, thereby eliminating or minimizing the previously mentioned problems. Therefore, the tend to feel more responsive. I prefer four bar link systems, but that dosen't mean that single pivots are bad. There are still a lot of single pivot designs out there, and if implemented right, there not bad.

  7. #7
    Jm.
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    Quote Originally Posted by sddhrider
    The main difference between the two is the path the rear wheel takes when the suspension is compressing. Single pivot designs tend to move the rear wheel in an arc as the suspension moves through it's travel. This in turn changes the length of the wheel base. It is this that cause things like brack jack and bio pacing when braking or pedaling respectively. Four bar link designs attempt to correct this problem. By having multiple pivots the rear wheel travels in a much straighter path, thereby eliminating or minimizing the previously mentioned problems. Therefore, the tend to feel more responsive. I prefer four bar link systems, but that dosen't mean that single pivots are bad. There are still a lot of single pivot designs out there, and if implemented right, there not bad.
    Actually that is not quite true. The rear end still moves in an arc with horst link bikes, it's not the same arc as with a single pivot, but it is also not drastically different. There was a myth that FSR/horst link bikes had a vertical, or near vertical wheel path. That just isn't true though when you plot it out. There's a virtual-pivot somewhere in the area above the BB, but the virtual pivot is still a point that the rear axle rotates about, and that eliminiates any chance of a "vertical travel"...
    I know in my heart that Ellsworth bikes are more durable by as much as double. AND they are all lighter...Tony Ellsworth

  8. #8
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    excellent tech talk...how about the ride?

    Quote Originally Posted by Jm.
    Actually that is not quite true. The rear end still moves in an arc with horst link bikes, it's not the same arc as with a single pivot, but it is also not drastically different. There was a myth that FSR/horst link bikes had a vertical, or near vertical wheel path. That just isn't true though when you plot it out. There's a virtual-pivot somewhere in the area above the BB, but the virtual pivot is still a point that the rear axle rotates about, and that eliminiates any chance of a "vertical travel"...
    thanks for summarizing the tech side....

    any thoughts on a hypothetical side by side comparison on how each would feel on drops?

    Let's say smaller drops to flat (should feel somewhat different...right)?

    P.S....I love my Bullit, this is not an "anti single pivot" rant...but the Specialized looks like it soaks up the drops so much better.

    Is this true???

  9. #9
    Jm.
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    Quote Originally Posted by freeriderB
    thanks for summarizing the tech side....

    any thoughts on a hypothetical side by side comparison on how each would feel on drops?

    Let's say smaller drops to flat (should feel somewhat different...right)?

    P.S....I love my Bullit, this is not an "anti single pivot" rant...but the Specialized looks like it soaks up the drops so much better.

    Is this true???
    See...that is completely a function of the linkage part, not the horst-link part. You can design a linkage bike like horst-link FSR, OR a kona style, to be either straight, falling, or progressive. It's going to depend...if it's designed progressive, it should sink more into it's travel on the drop and resist bottoming...to do the same a straight or falling rate needs a stiffer spring, making it a harsher ride overall...blah blah blah....

    Having the pivot above or below the axle is not going to affect this.
    I know in my heart that Ellsworth bikes are more durable by as much as double. AND they are all lighter...Tony Ellsworth

  10. #10
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    Quote Originally Posted by freeriderB
    thanks for summarizing the tech side....

    any thoughts on a hypothetical side by side comparison on how each would feel on drops?

    Let's say smaller drops to flat (should feel somewhat different...right)?

    P.S....I love my Bullit, this is not an "anti single pivot" rant...but the Specialized looks like it soaks up the drops so much better.

    Is this true???
    I would say soaking up drops has more to do with shock valving and leverage ratios than linkage design. Linkage designs affect pedalling, braking and high speed bump absorption.

    If all you plan to do is drop things a burly single pivot with a well tuned shock is what you need. Less moving parts to develop slop.
    Turn your head and cough.

  11. #11
    BJ-
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    lemmie think...

    ok...keeping in mind a four bar linkage etc. enables more vertical wheel movement than a singe pivot design which some people consider to be better. (i do so this may be a bios opinion) then dropping on a single pivot bike would be as smooth but on landing the wheel would be moving towards the bike...instead of simply up and down...therefore i guess a four bar might be better to drop on??? (u may get away with more sketchy drop son a four bar linkage???) anyway im gunna give me bike shop a call and find out coz thats a really good ****ing question! cheers boys!

  12. #12
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    Can not compare them that way...

    As Jm. said, most four bar bikes have wheel paths that are very similar to single pivot bikes. The big advantage is reducing chain lengthening, balancing out the rider input forces, and neutralizing the braking forces (yuck, what an aweful sentence!).

    You can not say that: single pivot is better/worse than four bar on drops.

    Take a bike like the Balfa BB7: that bike has a much more effectively "vertical" wheel path than a Specialized Demo 9. The balfa's high pivot mean that the wheel is going to move backwards as it moves up, then forwards during the second half of it's travel. The Demo 9 is going to move back for a bit, but pretty soon (much earlier than the bb7) is it going to start moving forwards. Which bike is better for drops? Who knows. Which bike feels faster at flying through rough sections (assuming that the bb7 has a floating brake when braking) - the bb7's rearward axle path will help out here. This is the same principle that Canfield uses for their bikes.

    It's much more complicated than vertical vs. curved axle paths. There is no such thing as a "vertical" axle path, just ones that change curvature vs. ones that have a fixed radius (i.e. multilink Vs. Single pivot).
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  13. #13
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    Strictly talking drops, axle path shouldn't matter. Again, axle path is designed for bump absorption and pedaling. The VPP and i-Drive put a premium on axle path.
    Look at Bender. He's hit a wall, no pun intended, with shock damping. He used to ride a Karpiel and now he's on a Kona. Two different linkages but the shock is the limiting factor for him.
    Turn your head and cough.

  14. #14
    TNC
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    Noel, you mention that rearward path on the bb7...

    Quote Originally Posted by knollybikes.com
    As Jm. said, most four bar bikes have wheel paths that are very similar to single pivot bikes. The big advantage is reducing chain lengthening, balancing out the rider input forces, and neutralizing the braking forces (yuck, what an aweful sentence!).

    You can not say that: single pivot is better/worse than four bar on drops.

    Take a bike like the Balfa BB7: that bike has a much more effectively "vertical" wheel path than a Specialized Demo 9. The balfa's high pivot mean that the wheel is going to move backwards as it moves up, then forwards during the second half of it's travel. The Demo 9 is going to move back for a bit, but pretty soon (much earlier than the bb7) is it going to start moving forwards. Which bike is better for drops? Who knows. Which bike feels faster at flying through rough sections (assuming that the bb7 has a floating brake when braking) - the bb7's rearward axle path will help out here. This is the same principle that Canfield uses for their bikes.

    It's much more complicated than vertical vs. curved axle paths. There is no such thing as a "vertical" axle path, just ones that change curvature vs. ones that have a fixed radius (i.e. multilink Vs. Single pivot).
    And how this will help in fast, rough, choppy terrain. Does that have to do with the wheelbase effectively lengthening here or another dynamic of that bike's design? I notice that either one of my Bullits always do much better when I just let them go over really rough terrain than when I start intervening with some braking (choke,choke), which I presume starts to shorten the wheelbase (among other negative things). Just how much of a positive dynamic is a lengthening wheelbase in these conditions?

  15. #15
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    Quote Originally Posted by TNC
    And how this will help in fast, rough, choppy terrain. Does that have to do with the wheelbase effectively lengthening here or another dynamic of that bike's design? I notice that either one of my Bullits always do much better when I just let them go over really rough terrain than when I start intervening with some braking (choke,choke), which I presume starts to shorten the wheelbase (among other negative things). Just how much of a positive dynamic is a lengthening wheelbase in these conditions?
    if you think about the angle of the terrain forces vs. the angle of axle movement, those of which are equal will give less resistance to absorbing the impact. So its not so much a lengthening of the wheelbase which is mearly a consequence, but the rearward axle motion which more closely corresponds to the force direction of the bumps.

    The problem with braking over the rough with your Bullit has to do with the swingarm mounted caliper (the axle paths tie in here as well), and here we get into the floating brake debate....for another time

    it wouldnt be accurate to point out the behaviors relating only to wheelbase lengthening; that is just one (dimensional) component of the problem.

  16. #16
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    I owned an Enduro for a year and am now riding a Heckler. I now think FSR is overrated. A single pivot with the 5th element coil shock is far sweeter than my Enduro was with a Fox Vanilla! I have not noticed any of this "brake jack" either. Maybe because this bike handles so well I am using the brakes far less in the rough sections. I'm sure the Enduro would have been nice with the 5th too. But I was also having trouble with the pivots loosening up.

  17. #17
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    I used to have a Bighit pro, with the 8" biglink & Fox vanilla RC. It was a fun bike.

    I replaced it with a Bullit with a 5th element. All my parts swapped over (I needed a 26" rear rim & tire). The main thing I noticed between the two bikes was geometry, the shocks, and weight. There is a slight difference in the suspension performance, but this difference is outweighed by the other differences.

    The bullit is quite abit taller and steeper than the bighit. Bighit felt more stable, bullit feels more nimble in tight, slower stuff. I have gotten used to the bullit, and can charge on it, but the bighit made my balls feel bigger when I was pinning it. I also liked the short chainstays....front end pulls up really easy.

    The 5th element has a hugely different feel from the fox RC. It took me awhile to get it set up so it sagged 20%, had enough SPV pressure to pedal well, but not have a dead feel. I also cranked in the progressive dial a bit. This was HUGE....I could set my bike up supple and still SPRINT!

    Weight- L bighit with biglink and shock- 13.5 lbs. L Bullit with shock- 10 lbs. I also went from a Stratos S8 fork- 13lbs to a Shiver 10lbs. 6.5 pound difference! Sprints better, climbs better, mo' manuverable.

    Suspension. I feel like the Bullit stomps drops as well as the Bighit. It rolls through choppy terrain faster & smoother due to the 26" wheels. I can feel the chain kicking the pedals more at speed, and my chain bounces around on the cogset more, due to the more drastic changing chainline. Annoyance. I feel a litte more flex out of the bullit when cornering, but it doesn't affect anything.

    I prefer the light weight, durability, simplicity of the bullit. I wish it had a little different geometry...slacker, lower bb, little longer wheelbase. I will consider the Orange 223, Chumba Wumba F4 and Turner DHR for my next frame.

  18. #18
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    Not entirely a fair comparison...

    A Bullit is far more versatile bike. It can be made as an XC or DH/FR bike. The BigHit is not that flexible and is geared more towards DH/FR. Because of that both compromise some performances in different situations. That is hard to say for a diehard S fan and owner of a FSR, Enduro and BigHit!

    That said here's a simplified breakdown of pros & cons. Keep in mind the varience between the pros and cons are quite small and often overcome by rider skill and style.

    Big drops Advantage Bullit
    Pedaling in rough Advantage BigHit
    Active braking Advantage BigHit
    Durability Advantage Tie
    Maintanence Advantage Bullit
    Versatility Advantage Bullit
    High Speed Advantage BigHit

    Can't really compare on what the pros ride because they are paid to ride any given bike and their skill level makes up for any perceived differences. Berrecloth is the BEST example. He ripped when he was riding his Bullit. He still ripps while riding his BigHit. It's all skill.

    I reality both are excellent bikes and you need not explain your choice to anyone.

    Good luck!

  19. #19
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    I do beleive I said that four bar links attempt to correct this problem. How well they do it is a whole other matter. However, I did over simplify the situation. There are many other factors which some of you have mentioned. One could write a book on the differences. Also, if one design was truely better than another, second best would have all but dissappeared by now. The bike companies themselves have been tyring to figure this out since the 90's.

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