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  1. #1
    Cfletcher
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    ... and if we just ... VT2: SPV Setup issues

    Howdy ya'll... just got my new VT2 last Friday and rode it twice this weekend... damn that thing kicks ass! The handling is absolutely killer compared to my old bike (Schwinn Rocket 88 Stage 3)

    I have some issues with the sag though that I wanted to post.

    I weigh 215 and am 6' 4", so I got the XL Frame (22.5").. it's sweet, it's the first time I have ever mounted a bike where it felt like it was the right size for me!

    BUT - No matter what I do, I have too much sag (like close to 3 inches). I want 30% sag, so I am looking for 1.75 ". With the sag the way it is, I am expending much more energy on the climbs than before, which really sucks because I decided to XC race this year... which means lots of balls-out climbing. Heck, I'm already in bad enough shape, so I need all of the help I can get. This is the first SPV bike I have ever owned or worked on, (and regarding bike maintenance, I am still rather novice). Basically, when I am climbing the same hills as I did with my old bike, when it gets steep or techincal it now feels like I am doign a "wheely", and in fact my front tire comes up sometimes. It just feels like I am trying way too hard now.... I brought the seat post up some but then my pedal reach is too far.

    I have 170 lbs. in the main (top) chamber, and like 110 lbs. in the bottom (SPV) chamber. According to the manual I don't think I should put any more air in there than that right? This guy on the trail mentioned that you can adjust the "allowable" sag using a nut on the bottom of the whole shock (like the underside of the SPV area) but the manual seems to indicate that you should not touch that valve. The guys at Performance seemed to have really no clue how to adjust it... that was quite disappointing as well....

    So, does anyone have any good ideas for me? I need to improve the climbability on this thing by tomorrow if I can.

    Thanks!!!!!!

  2. #2
    mtbr member
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    Mountain Bike Action

    Hey Fletcher,

    I don't have your bike but I am considering buying a VT2. Anyhow I bought a few mags for research this weekend and in the latest Mountain Bike Action they go through SPV setup. I don't have it here with me so I don't know for sure.

  3. #3
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    Ignore the manual- the pressures printed there are all wrong. Increase your main chamber pressure till you get the sag you want. The SPV chamber is used to set the "platform" threshold where the suspension will move. Generally the SPV chamber is about 20-30 psi lower than the main chamber. Once both chambers are set- recheck your sag since the SPV chamber will affect sag to a small degree.

    As for lofting the front wheel on climbs- don't move the seat up- try moving it forward on the seat rails. Also, if it a stock VT, the handlebars are probably at seat level- try moving the bar lower by taking some shims from under the stem and placing them on top of the stem. By lowing the bar you will shift some weight forward to help keep the wheel down on climbs. I use a flat bar and it is about 3.5"-4" below the seat height.

  4. #4
    Cfletcher
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    Quote Originally Posted by VT no 1 2 or 3
    Ignore the manual- the pressures printed there are all wrong. Increase your main chamber pressure till you get the sag you want. The SPV chamber is used to set the "platform" threshold where the suspension will move. Generally the SPV chamber is about 20-30 psi lower than the main chamber. Once both chambers are set- recheck your sag since the SPV chamber will affect sag to a small degree.

    As for lofting the front wheel on climbs- don't move the seat up- try moving it forward on the seat rails. Also, if it a stock VT, the handlebars are probably at seat level- try moving the bar lower by taking some shims from under the stem and placing them on top of the stem. By lowing the bar you will shift some weight forward to help keep the wheel down on climbs. I use a flat bar and it is about 3.5"-4" below the seat height.
    The manual really clearly says DO NOT use air pressure above 175 lbs. Are they saying this because they are worried that I might damage the shock? You are the 2nd person that told me to go above this setting. The bike shop guy says to do body weight + 10 lbs. So, for me it would be 225 lbs. You don't think this will hurt anything?

    Sorry to doubt you - I am just worried that I will damage my brand new bike, ya know?

  5. #5
    Reviewer/Tester
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    Heheheheh...you are making the exact same mistake as I did at first. You are mistaking the main shock pressure limit with the SPV limit.



    Here is what you do: Set your main shock pressure at your *body weight* plus 10/20 psi.

    Set your SPV at *half* your body weight.

    Be aware that when you remove the pump from the schrader valves, you lose some pressure from the shock, so compensate for this.

    Try that...let us know how you like it.


    R.
    Last edited by Rainman; 06-14-2004 at 08:51 PM.

  6. #6
    mtbr member
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    Interesting...........

    [QUOTE=Rainman]Heheheheh...you are making the exact same mistake as I did at first. You are mistaking the main shock pressure limit with the SPV limit.



    Here is what you do: Set your main shock pressure at your *body weight* plus 10/20 lbs.

    Set your SPV at *half* your body weight.

    Be aware that when you remove the pump from the schrader valves, you lose some pressure from the shock, so compensate for this.

    Try that...let us know how you like it.


    Rainman, I have been setting my main chamber pressure at 160 and my SPV at 75. I weigh 190 without gear. Using your formula I should be at 200-210 in the main and 100-105 in the SPV. That would be higher than what the manual recommends for the Main(max 175) and the SPV (max 100). The setup I have been running has been good but always looking to improve. Wondering why the manual has those limits? I do have a CaneCreek shock on a Bike E! that recommends you take body weight and add 10 to 20 lbs. So your advice makes sense.

  7. #7
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    Quote Originally Posted by Rainman
    ..manual recommends for the Main(max 175) and the SPV (max 100). The setup I have been running has been good but always looking to improve..
    Just rechecked my shock manual and the SPV chamber- blue valve- pressure range is 50-175 psi

    The manual does not give a pressure range for the main chamber- black valve- but the pressure tables off of Giant's site for setting the shock show says to set the main chamber at riders weight minus 20 psi. Also the tables show pressures up to 250 psi.

    For a 215 lb rider a good starting place should be about 130-140 psi SPV chamber and about 190 psi main chamber.- make sure to note confuse the two chambers.

    I weigh about 195 lb and use 130 SPV and 160 main.

    Also note that the above pressures are if the shock is set for the 5.7" travel. In the 5" travel mode the pressures will be less- don't know why (probably something to do with the shock linkage ratios). I do know that when I tried the 5" travel I was using 105 psi SPV and 130 psi main to get 25% sag.

  8. #8
    Reviewer/Tester
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    Manitoo specs the main for 300 psi and the spv for 175. [max].

    I made this mistake when I was first setting up my rear shock on the VT-2, but thankfully I was sorted out by more knowledgeable riders on the forums.

    I run my weight [180lbs] plus 20psi in the main and half my body weight in the SPV chamber.

    This gives me a ride on the firm side of 'plush' but suits my style of riding because I jump everything that isn't moving..

    Don't get confused by the manual like I did. You need to have a good pressure in your main to get a balanced feeling between the front and rear SPV shock/fork platforms.

    If I want 'plush' I just let a smidgen [10-20psi] out of the main and leave the SPV where it is.

    This gives me a softer ride on the bumpy singletracks i regularly go on.

    However...as I said, my 'normal' settings are: 200psi main and 90psi SPV.

    Try it out yourself... see if i'm right..


    R.
    Last edited by Rainman; 06-14-2004 at 08:58 PM.

  9. #9
    XC rider/racer
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    Wheelies

    The wheelies youre experiencing when climbing are because the front end is getting too light....theres few ways to tackle this--

    *Decrease the amount of front fork travel....a bit of experimenting may be needed here to find the "sweet spot" where youre getting good travel to soak up the downhills, and yet can still keep the front end from getting too light in those sharp climbs. Remember, the more fork travel youre using, the more likely it`ll want to wheelie during climbs.

    *When doing these technical and steep climbs you really need to reach a position where youve got enough weight forward to keep the front wheel steering comfortably for you, and yet at the same time keep enough weight back too maintain traction on the rear tyre.
    I`ve done climbs where I`ve had my chin only an inch or two over the stem to keep the front end from lifting, yet all the while keeping my butt glued to the seat to keep rear traction...but hey, it works

    * If youve got a fairly short stem, fitting a longer one will get more weight forward over the front wheel helping steering on those steep climbs.

    Hope this helps a bit
    Cheers

  10. #10
    bro not pro
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    SPV Chamber Volume adjust

    Hey ... nice thread ya got going here ... I'm fairly new to a Manitou Swinger 4 Way Air shock, although on a different bike, but alot of what you are talking about applies ... Anyways, what's the deal with the SPV volume adjuster ? Have you played with it ? Recommendations appreciated. -thanks
    G O N Z

  11. #11
    "El Whatever"
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    I don't have an SPV shock but I guess that the adjusting nut on the SPV chamber regulates the progessivity of the shock's travel.

    I'm not sure but I guess dialing it inwards makes the shock less bottoming prone so it stiffens as the shaft travels into the shock. So you would not bottom it and gives you that "infinite travel feel" Curnutt valved shocks are supposed to give.

    The other way makes it more linear an lets you bottom more easily.
    Check my Site

  12. #12
    Combat Wombat
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    Exactly right.

    Quote Originally Posted by Warp2003
    I don't have an SPV shock but I guess that the adjusting nut on the SPV chamber regulates the progessivity of the shock's travel.

    I'm not sure but I guess dialing it inwards makes the shock less bottoming prone so it stiffens as the shaft travels into the shock. So you would not bottom it and gives you that "infinite travel feel" Curnutt valved shocks are supposed to give.

    The other way makes it more linear an lets you bottom more easily.
    As far as where to set it, it all depends on your size and what you are doing with the bike.
    I weigh 155lbs and ride mostly crosscountry with a few jumps and drops, nothing more than 2 feet. I run mine full open. I found that it is pretty sensitive and that by turning it in even 1 turn made a noticable difference in the amount of travel I was getting.
    Giants recommendations will at least give you someplace to start.
    http://www.giantbicycle.com/uk/050.0...50.030.955.asp

    Brian

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