help me tunning my first dh rear shock- Mtbr.com
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  1. #1
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    help me tunning my first dh rear shock

    hello

    well yesterday i bought my first freeride dh bike, its a 2010 umf freddy, it has 160mm front marzocchi 55 rv fork and a 2010 roco marzocchi rear shock, when i bought the bike it came with a 450lb spring, im 13 years old and 50kg so it was way to hard for me, today i bought a 300lb spring and well im ajusting my shock, im trying calculating how much preload and air pressure i should use.

    at the moment im using no preoload and 20 psi and i like how it feels, i found that at my weight i should use 70 psi, well my shock manual says that.

    i think im using a wrong spring

    please help me

  2. #2
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    try this as a starting point in figuring out what spring to get:

    http://www.tftunedshox.com/info/spring_calculator.aspx

    then read your owner manual (I recently got a Roco Air WC and found the tunning info online) different frames like different sag, but generally you want 30-35% sag with your weight evenly on your bike (tune the front as well). Then go from there.

    It helps to have air shock in my case since I can easily measure sag (much harder with coil shock I used ebfore) and tune it very easily without having to buy a new coil, or changing conditions.

  3. #3
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    Quote Originally Posted by adumesny
    try this as a starting point in figuring out what spring to get:

    http://www.tftunedshox.com/info/spring_calculator.aspx

    then read your owner manual (I recently got a Roco Air WC and found the tunning info online) different frames like different sag, but generally you want 30-35% sag with your weight evenly on your bike (tune the front as well). Then go from there.

    It helps to have air shock in my case since I can easily measure sag (much harder with coil shock I used ebfore) and tune it very easily without having to buy a new coil, or changing conditions.
    i dont know which is my wheel travel

  4. #4
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    Quote Originally Posted by marc =)
    i dont know which is my wheel travel
    6.7 inches per the umf website.
    Build.
    Ride.
    Repeat.

  5. #5
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    Quote Originally Posted by schneidie
    6.7 inches per the umf website.

    thanks so much

    EDIT: i got 147 as a reccomended spring rate, does that mean i need a 147lb spring?

  6. #6
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    Quote Originally Posted by marc =)
    thanks so much

    EDIT: i got 147 as a reccomended spring rate, does that mean i need a 147lb spring?
    Marc,
    Did you mess up your units? That doesn't even sound close...

    Edit: I'm getting 265 to 324, assuming a 2.25" stroke, and 214 to 263 w/ a 2.5" stroke, both on the 33% sag (TFTuned's calc).

  7. #7
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    The positon that you set sage on the bike will also make a big difference in suspension feel.

    Lots of variation between setting sag seated vs. the off the seat/dh riding position.

    Use the shock/bike/tuner sag recommendations to get you in the ballpark and then dial things in for your riding style and preferences.

  8. #8
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    Quote Originally Posted by Norman Clydesdale
    The positon that you set sage on the bike will also make a big difference in suspension feel.

    Lots of variation between setting sag seated vs. the off the seat/dh riding position.

    Use the shock/bike/tuner sag recommendations to get you in the ballpark and then dial things in for your riding style and preferences.
    nevermind i dont need to tune it because i think i trashed my shock, yesterday my dh teacher took all the air out of my shock and now i found something called cavity and i think that my happened to my shock and ive used it all day without air and maybe my 2 day bike is now gone.

    does my shock still works and if it does has cavity what i do?

  9. #9
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    You will ne alright....they are a pretty durable shock

  10. #10
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    If my "DH teacher" let all the air out of my shock then let me ride it, I wouldn't let him near my bike ever again, let alone teach me how to ride DH.
    I'd rather have a bottle in front of me than a frontal lobotomy.

  11. #11
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    Re inflate the shock, as a rough guess I suspect you need around a 250 spring, initially you might ride with a lower psi, but as you improve you will find you use more big hit performance and might have to up the psi and use a heavier spring.

    Quote Originally Posted by DH Teacher
    Thats a hill... Point down it, hold on and grin like a muppet, oh and try not to fall off

  12. #12
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    Quote Originally Posted by sdo1982
    Re inflate the shock, as a rough guess I suspect you need around a 250 spring, initially you might ride with a lower psi, but as you improve you will find you use more big hit performance and might have to up the psi and use a heavier spring.
    I wish i could inflate it but i dont a shock pump and the store was closed yesterday, but today after school im going to buy one and inflate it, i just hope my shock keep working till i buy the pump.

    Thanks so much for all your help guys

    And about my dh teacher, well here on mexico dh is just beginning so there are like not very experienced at all.

  13. #13
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    Well if there is little experience (OT) then you really should be learning as much as possible so that you can help spread it with your friends and such...also if an instructor is not 100% sure why they are doing/did something then you may want to look for advice else where.

    Also kinda makes sense that he let the air out...making the shock more plush...but doing it in the wrong way.

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