DHX Air setup tips for XCL?- Mtbr.com
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  1. #1
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    DHX Air setup tips for XCL?

    I need a starting point for the DHX Air shock on my new XCL. The Fox online manual isn't all that helpful about a couple of things. I'm about 220 in riding gear, trails are technical/rocky/rooty. Can someone suggest main and boost pressures, etc.?

  2. #2

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    Hey Chuck How are you doing? I would start with 10 lbs under your body weight.
    • Shock Set-Up The Fox DHX Air has an adjustable bottom out feature that requires some additional set up to coincide with the XCL suspension. Step 1) Release the air from both the main chamber and the bottom out reservoir. 2) Cycle the shock several times, periodically releasing the air from both chambers until you feel they are both completely empty. 3) Turn the bottom out dial all the way to the + side. 4) Fill the bottom out air chamber to 150PSI. 5) Fill the main chamber as per manufacturer’s suggestion based on weight, riding style, etc. (We personally run 10PSI over body weight)

  3. #3
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    Thanks Jason!

    Hey... can we get a Chumba logo thumbs-up emoticon?

  4. #4
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    Quote Originally Posted by chucko58
    Thanks Jason!

    Hey... can we get a Chumba logo thumbs-up emoticon?
    How about some Chumbie T-shirts??? Where do we get those?

    BTW, thanks for the DHX set up info, Jason.
    Extreme stationary biker.

  5. #5
    nerfherder
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    Quote Originally Posted by ChumbaJason
    Hey Chuck How are you doing? I would start with 10 lbs under your body weight.
    • Shock Set-Up The Fox DHX Air has an adjustable bottom out feature that requires some additional set up to coincide with the XCL suspension. Step 1) Release the air from both the main chamber and the bottom out reservoir. 2) Cycle the shock several times, periodically releasing the air from both chambers until you feel they are both completely empty. 3) Turn the bottom out dial all the way to the + side. 4) Fill the bottom out air chamber to 150PSI. 5) Fill the main chamber as per manufacturer’s suggestion based on weight, riding style, etc. (We personally run 10PSI over body weight)
    Hey, this is great info... that I could have used last week. LOL.

  6. #6
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    I'm still struggling with the DHX Air settings. I haven't seen anyone describe how the boost valve is supposed to respond to changes in reservoir pressure and/or main air pressure. That's my real complaint so far, that the adjustments are inscrutable.

    I can either get it firm with no pedaling woes (at body weight - 10 PSI), or plush with pedal bob with lower pressure, but not plush without the pedal bob. I had several pedal strikes on my last ride at the plush setting, which is really unusual for me on this particular trail. I guess this suggests there's too much sag, so I need to pump up the main chamber some.

    I haven't seen or felt the shock bottom out yet. I'm only running about 1-1/2 turns of bottom out with 150 PSI in the reservoir. I usually finish a ride with 1/2 - 3/4" of travel left on the shock. The fork (Fox 32 TALAS RLC) isn't bottoming out either, so maybe this is OK. I'm not a gonzo rider, just a Clyde.

    It seems like I have to dial up a lot of rebound to keep the rear wheel from bouncing me in the air on water bars, but this might be riding technique.

    Any suggestions? Other than "ride the snot out of it and play with the settings," that is - I'd love to but life is getting in the way. It sucks having to work to pay for the bike.

  7. #7
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    Have you taken a look at Fox's online manual yet?

    http://foxracingshox.com/fox_tech_ce...dhx_air_50.htm

    The boost valve basically adjust the range of the pedaling platform (at least that's how I understand it).

    You may want to lower the PSI in the boost chamber down to 125 or so and just keep the main one where you like it.

  8. #8
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    Thanks dubjay, but the explanation there still doesn't quite tell me what I want to know.

    This comes closer, after I stared at it for a while:

    http://foxracingshox.com/fox_tech_ce...x_air_tech.htm

    Here's what I think is going on, based on the animations. Please pardon the engineer-speak, I read too many race car tech books when I was younger.

    The boost valve controls the high-speed compression circuit. (I presume there's a fixed low-speed compression bleed.) The point at which the transition to the high-speed circuit (boost valve) happens depends not only on the ProPedal knob setting, but the static reservoir air pressure and the bottom-out chamber (AKA reservoir) size.

    Not only that, but the air spring rate rises with shock travel, and the increase is a function of the reservoir pressure and size. And the threshold for the high-speed compression circuit increases with it.

    So the three settings interact, but you have no control over the low- or high-speed compression damping forces - just the point at which you transition from one to the other.

    Any shock geeks want to confirm or revise my theory?

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