Results 1 to 21 of 21
  1. #1
    mtbr member
    Reputation:
    Join Date
    Jul 2009
    Posts
    240

    Anyone seen a dual rear suspension and stem suspension Mountain Bike?

    I was at the LBS today and saw a customer bring in an oddly looking vintage mountain bike. It looks like it was when full suspension was still a new idea. In the front triangle where the rear shock usually was, there was a coil shock running vertically, then connected to the same linkage, a air shock (fox shock) running horizontally. Then on the stem, there was some sort of coil shock there as well. On the frame, it had the words 'JP MORGAN' on the downtube. I wish I snapped a photo, but does anyone have any more information on this bike? I tried searching google and wasn't able to find anything.

  2. #2
    Underskilled
    Reputation: CaveGiant's Avatar
    Join Date
    Aug 2007
    Posts
    4,111
    I have seen a few bikes using a rear shock on the front, and twin shocks on the back, but never both on the same

    The kona abracadabra (i think) has a dual rear.
    Why would I care about 150g of bike weight, I just ate 400g of cookies while reading this?

  3. #3
    RiffRaff
    Reputation:
    Join Date
    Jan 2007
    Posts
    429
    Karpeil Apocalypse.
    "If Liberace was alive, he'd be proud to ride that mofo."

  4. #4
    mtbr member
    Reputation: 53119's Avatar
    Join Date
    Nov 2008
    Posts
    2,804
    did you say coil on the stem? possibly an old Softride stem, maybe?
    i'm on my Last Herb
    RestInPeace Hook

  5. #5
    mtbr member
    Reputation:
    Join Date
    Dec 2009
    Posts
    174
    It must be really old because full suspension has been around awhile. My friend had a FS BMX back in 1975. Back then we called the rear suspension "mono-shock".

  6. #6
    mtbr member
    Reputation:
    Join Date
    Mar 2010
    Posts
    76
    Photo of one
    Attached Thumbnails Attached Thumbnails Anyone seen a dual rear suspension and stem suspension Mountain Bike?-apocalypse_description.jpg  


  7. #7
    mtbr member
    Reputation:
    Join Date
    Aug 2008
    Posts
    2,427
    yeah, dude had some funky ideas, there's a couple pics buried in the VRC board somewhere.
    (no, JP Morgan... vintage... not karpiel, they did it too, as did kestrel, but this guy's talking about before them.)
    If steel is real then aluminium is supercallafragiliniun!

  8. #8
    mtbr member
    Reputation:
    Join Date
    May 2010
    Posts
    353
    I must be missing something but wtf does that airshock do?

  9. #9
    Xtr=x0ē
    Reputation:
    Join Date
    May 2010
    Posts
    176
    Quote Originally Posted by chugachjed
    I must be missing something but wtf does that airshock do?
    I donīt know really, it shocks?


    top it off with a double barrel between the top of the rear triangle and the seattube and it would be the single most uber-awesome piece of machinery mankind has ever witnessed. Ever.

    I want to see FS bikes with shockposts and suspension stems, that would also be really cool. Highly idiotic but whgo else can say they have a quad suspension bike right??
    D8 is now off the hook.

  10. #10
    mtbr member
    Reputation: Broccoli's Avatar
    Join Date
    Jun 2008
    Posts
    5,769
    Quote Originally Posted by chugachjed
    I must be missing something but wtf does that airshock do?
    You can fine tune rate and bottom out without swapping coils I guess. Seems like an interesting idea.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Dec 2009
    Posts
    174
    Yeah looks like the top of the coil shock is mounted to a lever that the air shock is mounted to.

  12. #12
    aka greyranger
    Reputation: redranger's Avatar
    Join Date
    Feb 2004
    Posts
    507
    k2 did something with a coil onthe front with a linkage do not remember the manufactrer

  13. #13
    mtbr member
    Reputation:
    Join Date
    Jun 2009
    Posts
    833
    To me it looks like the coil would be a stiff shock and the air would do all the little work. In essance, it would be a dual stage setup. Once the air shock bottoms out, the coil shock will compress.

    The air shock looks to be one pivot point, the coil shock in the center and the hard point (frame) on the other side. To me, the center point would be the weak point; right where the coil spring would go.

  14. #14
    mtbr member
    Reputation:
    Join Date
    Oct 2007
    Posts
    517
    What about some bikes having a spring suspension stem? I seen one and was aghast!!! Wouldnt that go great on a Softride along with K2 forks with the computer/shock and backward mounted axle? Lets see how LOUSY a bike we can build. Lets call it the Corvair of MTBs and pool our money to get em built in India and sell them only in China at real inflated prices.

  15. #15
    mtbr member
    Reputation: Broccoli's Avatar
    Join Date
    Jun 2008
    Posts
    5,769
    Quote Originally Posted by hardwarz
    To me it looks like the coil would be a stiff shock and the air would do all the little work. In essance, it would be a dual stage setup. Once the air shock bottoms out, the coil shock will compress.

    The air shock looks to be one pivot point, the coil shock in the center and the hard point (frame) on the other side. To me, the center point would be the weak point; right where the coil spring would go.
    No, they will compress together - springs in series. A bit more complicated here as leverage ratio is position sensitive - air would move more as coil bottoms out. If I understood correctly the main idea was to tune how the bottom out happens? Was not it a model for folks who hack off cliffs and such?
    Last edited by Broccoli; 07-04-2010 at 12:57 AM.

  16. #16
    mtbr member
    Reputation:
    Join Date
    Jun 2009
    Posts
    833
    Quote Originally Posted by Curmy
    No, they will compress together - springs in series. A bit more complicated here as leverage ratio is position sensitive - air would move more as coil bottoms out. If I understood correctly the main idea was to tune how the bottom out happens? Was not it a model for folks who hack off cliffs and such?
    The spring will compress in series if they are set in series & they have the same compression rate. If the coil has a much stiffer compression rate, the air shock will compress first. Since I don't know the compression rates of either spring & it doesn't look like they are in direct series, I'm just guessing. It does look like they are offset; therefore must be using a lever.

    I've used a 2 stage spring on several projects. If the compression rates are equal or even up to double, they will act in series at a different rates. At (off the top of my head) a rate of 4:1, the will initially act as a 2 stage. There are also ways to set up springs coaxially to make a 2 stage shock.

  17. #17
    mtbr member
    Reputation: Broccoli's Avatar
    Join Date
    Jun 2008
    Posts
    5,769
    Quote Originally Posted by hardwarz
    The spring will compress in series if they are set in series & they have the same compression rate. If the coil has a much stiffer compression rate, the air shock will compress first.
    Springs are not psychic. They do not know they are in series. Force in two springs will be exactly the same and they will compress simultaneously.

    Obviously the displacement will be larger on softer spring - and a bottomed out spring is not an ideal spring. But the force is exactly the same. Each spring does not know the other exists - it is compressed proportionally to that exact same force. Harder spring would not "wait" for the other to compress.

    Obviously, all is not trivial with various non-linear effects - such as "platform" shocks, and variable and position sensitive leverage ratios in play. But I can not see how one can make a statement that one spring in series will "compress first".
    Last edited by Broccoli; 07-04-2010 at 12:35 PM.

  18. #18
    mtbr member
    Reputation:
    Join Date
    Jun 2009
    Posts
    833
    Quote Originally Posted by Curmy
    Springs are not psychic. They do not know they are in series. Force in two springs will be exactly the same and they will compress simultaneously.

    Obviously the displacement will be larger on softer spring - and a bottomed out spring is not an ideal spring. But the force is exactly the same. Each spring does not know the other exists - it is compressed proportionally to that exact same force. Harder spring would not "wait" for the other to compress.

    Obviously, all is not trivial with various non-linear effects - such as "platform" shocks, and variable and position sensitive leverage ratios in play. But I can not see how one can make a statement that one spring in series will "compress first".
    Depending on the stiffness of the springs, one may compress first.

    If you go to an extreme case and have a spring that will only compress under a 2 ton load and a spring that is designed to compress under 2 lbs load, guess what will happen...

    Technically, since they are in series, the 2 ton spring will compress, but will not bottom out and will not be visible to the naked eye.

    I will not say that in this specific case, it will or will not without directly knowing what the spring tensions are and if they are on a fulcrum.

  19. #19
    mtbr member
    Reputation:
    Join Date
    Aug 2009
    Posts
    44
    Quote Originally Posted by mickeydesadist
    What about some bikes having a spring suspension stem? I seen one and was aghast!!! Wouldnt that go great on a Softride along with K2 forks with the computer/shock and backward mounted axle? Lets see how LOUSY a bike we can build. Lets call it the Corvair of MTBs and pool our money to get em built in India and sell them only in China at real inflated prices.
    i had a coil sprung stem in the early nineties.

  20. #20
    mtbr member
    Reputation: Broccoli's Avatar
    Join Date
    Jun 2008
    Posts
    5,769
    Quote Originally Posted by hardwarz
    Depending on the stiffness of the springs, one may compress first.
    What do you mean by "compress"? Bottom out?

    Two spring in series are under the exact same stress. They compress as much under that stress as they would do alone. It does not matter if they are in series or alone. Yes, the displacement for a softer spring is larger.

    Not sure what was your argument, but anyway.

  21. #21
    more carbon=more awesome
    Reputation: The Understater's Avatar
    Join Date
    May 2007
    Posts
    1,323

    2Stage.

    2Stage Bikes. 2 shocks, one set soft and one set harder. Apparently works great.
    Attached Images Attached Images  
    Posting on the basis that ignorance shared is ignorance doubled.

Posting Permissions

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