rear suspension adjustment

Discussion in 'Road Series (S1.x, S2.x, S30)' started by mzweili, Jun 25, 2014.

  1. mzweili

    mzweili Guru

    I would like to know if there is a recommended value for the rear suspension adjustment.

    Taking in consideration the weight of the rider, how far should the PU spring stick out of the frame?

  2. ratz

    ratz Wielder of the Rubber Mallet

    Mark,Never could find


    Never could find anything on that myself... but I can share how I approached it.

    As far as I know the Elastomer basically dampens vibrations. If you hit something big the spring arm is going to bottom out no matter what and you are going to take a jolt. If I'm correct; you'd want to set it in the middle of the range and ride. If you think you feel too much of the road vibrations through your seat then dial the adjustment disc out so that the Elastomer is further into the frame. If you find the ride mushy or bouncy but smooth then dial it the adjustment disc into the frame so it push the Elastomer further out.

    It should be more obvious if you test ride without the seat cushions.
  3. mzweili

    mzweili Guru

    rear suspension setting

    here is the setting I have on my Silvio. I feel comfy with this. Compared to the harsh ride of non-suspended 700x23 tires, it smoothens the ride on rough road surface, that is all I was looking for.
  4. super slim

    super slim Zen MBB Master

    From the build reports, the

    From the build reports, the PU 4 donut spring is a TIGHT fit when installed with the larger donut diameter into the frame sleeve, which is the correct way.

    If the OD of the donut in your photo that is just covered, is 2 mm greater than the ID of the THREADED sleeve, then I THINK that that donut will not move when the suspension moves, so only 1 of the three valleys work as a spring, and your spring rate is three times higher than the minimum spring rate!!???????

    Try screwing the PU spring so that donut is 2 mm outside the sleeve, remove the seat back, and suddenly apply all of your weight to the rear of the frame, while someone watches the movement of the donut to see if it goes into the sleeve. Adjust the spring position until it stays out.

    If the suspension is still too stiff, then remove the PU spring and carefully file down the 3rd donut so the interference of the donut OD and the sleeve threaded ID is 1/2 of the existing interference, AND/OR add lots of rubber grease to this donut.

    Do NOT over file the donut as the PU spring shape is very unstable, but has a large deflection for a short spring length, due to the deep valleys, and needs the sleeve to stop it buckling.

    BEFORE you do any filing to the PU spring, get a spare one, just in case.

    If you are running 23 mm wide tyres, try going to 28 mm wide tyres as for me in Australia, with our ROUGH chip sealed roads, going to 28 mm Schwalbe Ultremo ZX tyres improved the comfort, and especially cornering grip and confidence dramatically.

    I will send a recommended tyre pressure for load on another post, as this can also effect comfort and grip.

    Super Slim

  5. mzweili

    mzweili Guru

    PU spring orientation

    Super Slim,
    When I was assembling my Silvio 2, I tried to get the larger part of the PU spring into the treaded hole in the frame, it was nearly impossible.
    There was already a discussion ongoing in July 2013 ( posts 26+.
    Finally I installed the PU the same way as Bob (Ratz) showed in its build diary ( post 7.
    On different pictures in the forum I see PU springs installed the same way as mine, (Mauler, Rick and others).
    I would like to know if it makes a significant difference.
  6. Robert Holler

    Robert Holler Administrator Staff Member

    I have tried all variations

    I have tried all variations of this - from just protruding to nearly all the way out and in my opinion the difference was negligible, and likely more of a perception anyway. It is less a "spring" and as was noted, is mainly taking up vibration during a ride and the harsh aspect of a jolt from the hard hits. At that it is a great benefit.

  7. bladderhead

    bladderhead Zen MBB Master

    There seems to be two

    There seems to be two versions of the back suspension. There is a part that is slightly shiny and shaped like a sombrero, and a rubber part shaped like an accordion. In the mzweili picture the sombrero has a smaller diameter than the accordion. This is the version I have. In the super slim picture the sombrero is wider than the accordion.

    After years of being mollycoddled by the Grasshopper I found the Silvio a bit bumpy. I screwed the metal disk up to the max. I inserted half a powerball between the metal disk and the accordion. A powerball has a slightly smaller diameter than the accordion. This makes a slightly longer travel. Feels better.
  8. Eric Winn

    Eric Winn Zen MBB Master

    I was under the impression

    I was under the impression the accordion was slightly tapered so one end has a bit larger diameter than the other end and that it makes a difference which way you install it in relation to the sombrero.

    So instead of two versions, it is two orientations - one where the accordion has the larger diameter against the sombrero and one where the accordion has the smaller diamter against the sombrero. Isn't this what super slim is saying?

    I haven't seen any of this stuff in person and I'm kind of visually oriented so I may have this all wrong.

  9. bladderhead

    bladderhead Zen MBB Master

    My mistake, Eric is right. 

    My mistake, Eric is right. The accordion has a narrow end and a wide end. Should I turn mine round? Does it make any difference?
  10. super slim

    super slim Zen MBB Master

    to see if adjustments make

    to see if adjustments make any difference, you could put the Silvio on digital bathroom scales with its rear wheel, and the front wheel leveled, and apply load the the rear of the seat frame and measure the gap decrease of the rear strut to the frame, then adjust the rear spring and retest the load for deflection.
    A second option is to turn the PU spring around and retest fully extended and fully retracted!

    Super Slim

  11. Jeremy S

    Jeremy S Dude

    About the insertion

    About the insertion direction: The narrow end of the rubber springy thing fits onto the plastic disk thing easier, which means the wide end of the springy thing goes into the frame. I think this is the original intent of the design.

    However -- I could not get the wide end of the spring into the frame without a very high level of effort (even with lubrication), at which point the spring jammed in the frame and absolutely could not be adjusted by turning the metal disk. I emailed/messaged Cruzbike about this a few times and eventually John told me to try flipping the spring around. So I did that and I'm keeping it that way.

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