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Vivid rebound tuning

Discussion in 'Downhill & Freeride' started by Sandwich, Jul 18, 2013.

  1. Sandwich

    Sandwich Pig my fish!
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    The knobs say "Ending stroke" and "beginning stroke" but are they comparable to or actually HSR/LSR circuits? ie, position sensitive or actually speed sensitive? I'm having a hard time deciphering the marketing lingo.
     

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  2. jonKranked

    jonKranked Press Button, Receive Stupid

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    i dunno about the vivid, but that's how compression was labeled on a 5th element :rofl:
     
  3. Nick

    Nick My name is Nick

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  4. Sandwich

    Sandwich Pig my fish!
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    that still doesn't answer my question. It alludes to more of a HSR/LSR setup, but all the other ad copy says 80/20.

    I already know their "application", and have the shock tuned comfortably, but I'm trying to understand the concept or mechanics as a way to better understand them as I tune.
     
  5. Nick

    Nick My name is Nick

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    Sorry.
    I have a Vivid r2c as my back up shock. I found the adjustments worked as described and consider them "position sensitive", not "speed sensitive". Also found that you couldn't have them adjusted drastically apart from each other or you'll feel the transition between the stages.

    Take it apart, snap some pictures, and post 'em here.
     
  6. bengxe

    bengxe Monkey

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    The way I understand rebound tuning, there's no difference between position sensitivity and speed sensitivity. Since the spring is providing the rebound force, the position determines the shaft speed.
     
  7. Steve M

    Steve M Turbo Monkey

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    There is a difference, though as you say, there is a position-dependent velocity ceiling due to the maximum spring force available at any given point in the travel. To be completely accurate, the Vivid's adjustments are high/low speed, and with most reasonable spring rates, it is possible to enter the HSR part of the curve in more than 90% of the travel, so to call it end-stroke is somewhat misleading. The LS adjuster is the dominant adjustment however.
     
  8. Sandwich

    Sandwich Pig my fish!
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    Cool, thanks guys. I wonder if they labeled them differently so the majority of us would be able to get into a comfortable adjustment zone easier?
     
  9. tacubaya

    tacubaya Monkey

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    If you fix the rebound damping, then the rebound speed depends not only on the force exerted by the spring (which is position dependent) but on the net force acting on the shaft. If you compress the shock completely (with a spring) and let it go, yeah the force will depend only on the spring, but because your tire is most of the time contacting the ground, supporting your weight and also receiving impacts from the terrain, the force trying to extend the shock would be:

    Spring force (KX) minus compressive forces (rider weight/inertia, impacts, whatever)

    This way, you could have low forces on any part of the spring extension and thereby, low shaft speeds and thereby, low speed rebound damping influence.
     
  10. Steve M

    Steve M Turbo Monkey

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    This is correct and complementary to my point above. Both low speed and high speed motions can occur almost anywhere in the stroke, but the respective probabilities of each are higher earlier/later in the stroke. That is to say, MORE low-speed motion occurs early in the travel than late in the travel, and MORE high speed motion occurs late in the travel than early in the travel. Because of this, a certain degree of position sensitivity can be inferred but it is not a thorough or fully practical way of understanding the damping.