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Thread: DHX 5.0 air

  1. #1
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    DHX 5.0 air

    i'm 190 on med xcl any good start points for air? pro pedal settings? i know it's all personal and ride conditions but wondering where others are at? any other options on pumps?
    thanks

  2. #2
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    First things first... I like the Topeak Pocket Shock DXG. It has a unique Schrader valve attachment that minimizes air leakage - which is crucial with the boost chamber on the DHX shocks.

    I've settled on my riding weight (including gear) less 10 PSI in the main chamber, the boost chamber unscrewed all the way, 100 PSI in the boost chamber, and zero or maybe 1 click of pro pedal (depending on how smoothly you pedal). Adjust the rebound slow enough so the bike doesn't launch you ass over teakettle on big water bars, and you should be set.
    Work is the curse of the biking classes.

  3. #3
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    here's where i'm at so far
    weight 190
    med xcl
    vanilla/dhx 50
    riding small drop/roots and loose track
    front i'm happy with
    rear not to sure
    190lbs main unscrewed all the way out rebound almost as slow as i can
    lower 150 with a few turns
    still a bit bouncy in rear
    thinking of dropping main to 170
    any thoughts?

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    I started with 175 in the main and 150 in the boost last year.
    With gear I was about 200 lbs. Now with gear I'm probably closer to 205 - 210.
    To be honest this bike bobs a bit much for my taste. I don't know if this issue is more
    of a DHX issue or a suspension design issue. I don't remember it bobbing this much
    when I first got the bike. It seems like it blows really easily through the first third of travel. I had to do a pretty steep road ride uphill yesterday for about 50 mins, kind
    of sucked. I did recently up the air pressure in the rear shock to 200 psi, didn't notice much difference. I recently switched the rebound from full fast to halfway.
    Any suggestions ? Anybody had better experiences with other shocks ?

  6. #6
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    Quote Originally Posted by le_buzz
    I recently switched the rebound from full fast to halfway.
    Any suggestions ? Anybody had better experiences with other shocks ?
    I noticed that when I slowed the rebound down about halfway, it made a big difference with bob. More than with the propedal dial. I have also been working on my pedal efficiency, which has helped too.
    Cycle tracks will abound in Utopia. ~H.G. Wells

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    Quote Originally Posted by chumbacabra
    I noticed that when I slowed the rebound down about halfway, it made a big difference with bob. More than with the propedal dial. I have also been working on my pedal efficiency, which has helped too.
    Are you using the DHX ? I have slowed the rebound but it still bobs. It does bob
    a lot less when I have a smooth pedal stroke but I don't always have the energy
    to maintain that.

    I remember that during the first few months after setting up the bike it bobbed
    a lot less than it does now. Maybe I need to just set the thing up from scratch, release all the air, cycle it a few times to make sure it's empty, then refill both
    chambers.
    I wonder if I should use less than 150 in the boost reservoir. Anybody have any
    thoughts on that ?

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    I usually spin circles pretty smoothly, but yesterday I was at a clinic and had the saddle all the way down, and I was getting a lot of bob from standing on the pedals. I didn't bother to dial it out - the clinic was mostly about bike handling and not hill climbing.

    I've found that I prefer a relatively low pressure in the boost chamber. Yesterday I used 90 PSI. My problem with the DHX Air has been not using enough travel, so I've been going softer and softer all around. I think I may have to jack up the ProPedal for standing, but otherwise it's pretty close.

    le_buzz, did your XCL come with the DHX Air or did you buy the shock aftermarket? Chumba specs the small RP23 air sleeve to keep the shock from blowing through the early and mid travel.
    Work is the curse of the biking classes.

  9. #9
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    Quote Originally Posted by chucko58
    I usually spin circles pretty smoothly, but yesterday I was at a clinic and had the saddle all the way down, and I was getting a lot of bob from standing on the pedals. I didn't bother to dial it out - the clinic was mostly about bike handling and not hill climbing.

    I've found that I prefer a relatively low pressure in the boost chamber. Yesterday I used 90 PSI. My problem with the DHX Air has been not using enough travel, so I've been going softer and softer all around. I think I may have to jack up the ProPedal for standing, but otherwise it's pretty close.

    le_buzz, did your XCL come with the DHX Air or did you buy the shock aftermarket? Chumba specs the small RP23 air sleeve to keep the shock from blowing through the early and mid travel.
    The DHX came with the bike. The bottom out knob is so hard to turn I didn't know I had it most of the way on until about a month ago when I really had to crank it and I finally got it to back all the way out. So I was running it with the bottom out most of the way toward on for a long time.
    So how does the amount of air in the boost chamber affect the ride ?
    From what I understand, using the bottom out is really only necessary for doing fairly large drops, which I don't do so maybe I don't even need it.

  10. #10
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    Quote Originally Posted by le_buzz
    So how does the amount of air in the boost chamber affect the ride ?
    As I understand it (which may be totally wrong)...

    As the shock is compressed, the reservoir fills with fluid, which causes a floating piston to move towards the bottom-out cap, compressing the air in the boost chamber.

    The pressure in the boost chamber controls high speed compression damping. More pressure = more force required for the high speed circuit to open up. As the shock compresses, the pressure in the boost chamber increases because of the floating piston. So as you get closer to bottoming out, the high speed circuit automatically takes more force to open up.

    The bottom-out dial controls the volume of the boost chamber - screwed in makes the resistance ramp up earlier and more sharply, screwed out makes resistance ramp up later and more gradually.

    The ProPedal adjustment (on the '07 and earlier models) controls additional spring pressure on the high speed valve. This is most effective when the shock is early in its stroke.

    Fox has a good Flash animation of how this all works here.
    Work is the curse of the biking classes.

  11. #11
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    Quote Originally Posted by le_buzz
    The bottom out knob is so hard to turn I didn't know I had it most of the way on until about a month ago when I really had to crank it and I finally got it to back all the way out.
    If you drop the pressure in the boost chamber before adjusting the bottom out knob, it'll turn A LOT easier.
    Work is the curse of the biking classes.

  12. #12
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    Quote Originally Posted by chucko58
    If you drop the pressure in the boost chamber before adjusting the bottom out knob, it'll turn A LOT easier.
    How would you do that on the trail without a shock pump ?
    Do you mean turning off the propedal first ? Anyway, I probably don't need to worry
    about that much since I don't do jumps. Thanks for the link, BTW

  13. #13
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    Quote Originally Posted by le_buzz
    The bottom out knob is so hard to turn I didn't know I had it most of the way on until about a month ago when I really had to crank it and I finally got it to back all the way out. So I was running it with the bottom out most of the way toward on for a long time.
    There are holes in the bottom out control knob that you are supposed to stick a 4mm allen wrench in to adjust the knob.

  14. #14
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    Quote Originally Posted by Thor821
    There are holes in the bottom out control knob that you are supposed to stick a 4mm allen wrench in to adjust the knob.
    Ahhhh, well no wonder ! Still, seems kinda funky to design a shock like that.
    The rebound is a pain to reach also.

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