My FOX DHX shock is missing something!

Hi Lee,
I have recently discovered your web site and have enjoyed your articles and insight. I know that you are a fan of the Specialized Enduro so I have a question about the Fox DHX 5.0 on this bike. I recently bought a 2006 Enduro Expert and I noticed that the Fox DHX 5.0 shock does not have a separate valve for the secondary cylinder.

I have a friend with a Santa Cruz Nomad with a Fox DHX 5.0 rear shock and his shock has a shraeder valve for the primary cylinder AND one for the secondary (bottom out) cylinder. In looking at the Enduro Frame it looks as though there is not enough room for the valve on the secondary cylinder to clear the frame, that much makes sense.

But, how do set or adjust the air in the secondary cylinder? Thanks in advance and keep up the great work on the site. I am a huge fan!

Drew Weerts

The more you click, the more I can post. Lee Likes Groceries dot com!

Hey Drew,

Thanks for the kind words.

Many FOX shocks have custom specs for individual manufacturers. For example, valving is often tuned for a bike’s spring rate and desired ride characteristic. Being a neighbor and riding buddy, Specialized has worked especially closely with FOX.

On your DHX Air, the boost valve pressure is set at the factory. You can’t adjust it, and do you know what — you don’t need to. Just dial in the bottom-out resistance, rebound and ProPedal, and you’ll be set. (That’s a lot to adjust!)

Most consumers (and shops) aren’t sophisticated enough to adjust every possible option on a modern shock. Removing that air valve is a smart way to make sure nobody screws up the ride of such a sweet bike.

Ride forth Enduro Bros!!!

— Lee

6 replies
  1. Malcolm says:

    Hey there,

    Here’s the thing about that though. I am 95 Kgs, and I have a mate that is 80 Kgs. Surely the bottom out is going to have to be adjustable for each of us? We both have an Expert, and when I hop on his bike, I pretty much bottom out even on 4 foot drops.

    So the question is, how can a factory set bottom out pressure thing be a one size fits all?



    ps, besides that, mint as bike.

  2. SoCal AL says:

    Like Lee said you’ll never miss the boost valve adjustment. I have an Enduro and a Reign X and the Enduro was much easier to dial in than my Reign X. The Reign X has the boost valve and it took a couple of weeks and a couple calls to Giant and Fox to figure out the best set-up for my riding style and weight. Just got my Enduro SL on monday and now I get to set up yet another bike.

  3. leelikesbikes says:

    Hey Malcolm,

    1. Every setup is a compromise, for the guys at FOX, the guys at Specialized and even for you when you set up your bike.

    2. That’s why PUSH Industries is doing so well tuning FOX suspension. Most bikes are made for a theoretical rider. On a medium Enduro that might be a guy who weighs 160 and rides moderately. If you’re heaver or lighter, or if you ride much easier or harder, you’ll benefit from a custom tune.

    2A. Example: I’ve always loved my 2006 S-Works Enduro. That thing rips. After PUSH worked on my shock, it was a completely different — even better — ride.

    2B. PUSH does not work on DHX Air shocks.

    3. For the vast majority of riders, a DHX Air has plenty of adjustment without messing with the boost valve.

    3A. The boost valve changes the effective spring rate and the amount of ProPedal. Yes, when you screw with it, your pedal platform changes.

    3B. That shock has a lot of ProPedal adjustment. You don’t need to mess with it via the boost valve pressure. It’s correct right where it is.

    3C. Even with a set amount of boost valve pressure, you can still adjust the volume of the boost valve. This is how you change your effective spring rate. If you’re not using your travel, back it out to enlarge the chamber, If you’re bottoming a lot, turn it in to shrink the chamber.

    3D. The main air chamber is still the key adjustment. If you’re heavier, run more main air pressure. You’ll probably want to dial in your volume as well. NOTE: Every time you change the main pressure, re-check your boost valve volume. I’m telling you — this shock has plenty of variables, and it can be tuned for just about anyone.

  4. Ian says:

    I’m switching out my DHX for this reason. I have the main chamber at 200 psi which gives me 25% sag. Even with the Boost all the way in I’m still bottoming out & I haven’t even hit anything big yet. I have played with the pro pedal & dampening, but I can’t find a happy medium. I just had the shock service by Fox, and they reset the pressure in the rebound chamber. As soon as they sent it back I knew I should have speced out a higher pressure. Fully loaded with my pack I weigh at least 200+ Lb’s
    I’m going to give the Rock Shock Pearl a shot, seems like more my cup of tea! I really wanted to run the Roco, but as with a true DHX the Schrader Valve won’t clear the frame. Which is the real reason it isn’t on the Enduro.

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