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noMAD man
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Discussion Starter · #1 ·
I have several rides on the DHX-A after getting it back from Fox for a stuck down condition. I weigh 190 on a large Bullit with a Van 36 on the front. Our riding area with an 11 mile trail has some fairly technical, rocky sections with some small jumps, and I ride fairly aggressively in this area because I know every rock in it. In this type of riding I wound up with 175 psi in the main chamber and 160 in the boost chamber with the boost chamber almost all the way closed. These numbers seem high to me in light of other air shocks I've run on Bullits and the light coil spring ratings I've run on coil shocks on this bike. I have a Manitou 4-Way Air that runs 110 in the main chamber and 105 in the SPV. My coil DHX runs a 400 lb. spring and the 5th E coil runs a 325.

That said, this DHX-A has been performing perfectly. I got the sag to run in the 30-40 % range like my other shocks with that 175 psi figure. I could not get the shock body to stop knocking the travel o-ring off the shaft under full compression until I turned the boost valve almost all the way in and set pressure to 160 psi. The Propedal is in the minimum position. Mk and others are right about the Propedal giving an initial harshness on this particular shock if you have it dialed up. You can't feel this shock bottom when it knocks the o-ring off the shaft, which seems weird. I tried more psi in the main chamber and boost chamber in many different configurations, but it would be too harsh almost immediately after just a little bit of mid-stroke plushness. This is an odd shock compared to the many different shocks I've owned. By that I mean that it doesn't always seem logical in some of its tuning and setup inputs. Regardless, after getting to this current setup, the bike has been awesome. The rear is plush in slow stuff and small objects, but as soon as the action picks up in fast, harsh terrain, the shock seems to firm up like it has a sophisticated compression shim stack or such inside. Oddly it reminded me a little of how my HSCV Marz forks react. Some of you know that feeling of how a Marz fork feels like it's going to be too soft and wallow in its travel, or spike, at speed because it just feels too good and plush at low speed. Jayem commented on how he didn't like this shock at high speed in rocky terrain, and I began to think that I couldn't get it to perform well in that scenario. After two days of carrying a shock pump with me and frequently futzing with it, I found that performance at speed that equaled and maybe bested my DHX coil. One issue to get to this spot was running less rebound control than I usually end up with on an air shock...air shocks usually seem to need more rebound damping dialed in to my experience.

So far so good. This shock has weirded me out, but honestly I can say I won't plug in any of my other shocks for this bike unless something breaks or changes on this shock. I find its real advantage to be that it rides plusher in its mid-stroke than anything else I've had, and after intense futzing I got excellent performance out of it at speed in rocks and on big hits. The Van 36 and this shock make for a very balanced package on my Bullit (6.3" in front, 6.5" out back) and make the bike an even better big hit trail bike than it was...and kept it at the 33 lb. mark.
 

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%$#$*!
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nice write-up! It's amazing that you got your bullit down to 33lbs.

how's the dhx compare to a 4-way? I have a 4-way on a titus locomoto singlepivot and like it for the most part except that the rebound feels too slow even when the knob's set at the fastest setting.

have you tried the dhx on a 4-bar set up? I'm curious about how it would work in that application as well.
 

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noMAD man
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Discussion Starter · #3 ·
Compared awhile back.

beefmagic said:
nice write-up! It's amazing that you got your bullit down to 33lbs.

how's the dhx compare to a 4-way? I have a 4-way on a titus locomoto singlepivot and like it for the most part except that the rebound feels too slow even when the knob's set at the fastest setting.

have you tried the dhx on a 4-bar set up? I'm curious about how it would work in that application as well.
Yeah, I've had a 4-Way Air for quite awhile running on another Bullit, and I reported the differences last month between theses two shocks. Basically the 4-Way is a firmer shock all the way around but still very good. I have an '00 Enduro Big Hit, but I've never run a stable platform shock on it...hasn't seemed necessary. It runs a simple Cloud 9 shock and works great. 33 lbs. on a Bullit isn't too hard to achieve, especially with a set of CrossMax XL wheels and running 2.5 Weirwolfs in tubeless setup.
 

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Very nice info TNC. So the DHXA is getting to be more and more interesting!

Curious about how you feel your non platform Bighit compares to your platform Bullit on bump compliance, both uphill and downhill.
 

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"El Whatever"
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You're in the same bandwagon that Tscheezy... he liked the DHXA for the same reason that you liked it... a plush midstroke.

You run a 400 spring on your DHXC??? So how much spring rate less you need with a platform shock?

BTW... If you have a 400 X 2.1-2.3 Fox spring laying around (preferably from a Vanilla), let me know if you want to part with it. My 450 is too stiff. I'm at 20-22% sag which is a bit too little except at those times when I lift he front wheel to take a hit with the rear wheel only (with my fork, you wouldn't like to hit something at speed).
 

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carpe mañana
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Sounds like you've got the shock prett dialed in. And that's a good looking rig, btw. Keep in mind that when you knock the o-ring off the shaft, you've gone way past the stroke of the shock. If you measure the stanchion (or shaft, whichever is the proper term on rear air shocks) you'll see that the stroke ends about 3-5mm from the end of the stanchion, so your o-ring ought to stay on there even after most severe ride. I've had mine set up way soft when I first got my DHX and the o-ring would get knocked off regularly. My brother in law, who's heavier than me, rode my bike around and bottomed it so hard, something got bent on the inside of the shock which prevented the metering valve from ever closing. I happen to be the first person to brake the DHX air, at least around here, so Darren from PUSH became interested in what happened and took a look at it. He had it for a few days before he finally was able to diagnose it. I am not sure whether it would have taken a while to get replacement parts, or whether it was just FUBAR, but I got a new shock from him, which is truly awesome. On a side note, I saw it apart, I also got a lesson from Darren on how it works, at least some of the things. It has shimmed compression and rebound, although the oil piston could use some optimization (among other things), like the pistons on RP3s do with the PUSH mod to free up the oil flow some more.

_MK
 

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Hi TNC

I could use a little help.
I bought a very well kept '99 Bullit from a friend of mine this last year and I thought you could probably tell me what the max size would be for the rear shock. It has a Fox Vanilla on it now that needs to be sent in to PUSH for service and I'd like to get something to put on while it is in the shop. My riding is mostly XC but I'm building skills to be able to do some downhill when I get this bike built up for it.
The Vanilla looks like an adapter was used to install it and that it is probably shorter than it needs to be.
Any help would be appreciated.
Thanks
 

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noMAD man
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Discussion Starter · #8 ·
Ah, the good ol' '99.

Old bullit shot said:
I could use a little help.
I bought a very well kept '99 Bullit from a friend of mine this last year and I thought you could probably tell me what the max size would be for the rear shock. It has a Fox Vanilla on it now that needs to be sent in to PUSH for service and I'd like to get something to put on while it is in the shop. My riding is mostly XC but I'm building skills to be able to do some downhill when I get this bike built up for it.
The Vanilla looks like an adapter was used to install it and that it is probably shorter than it needs to be.
Any help would be appreciated.
Thanks
I have one of those too. It's been an awesome bike, totally bulletproof, and in just about every configuration imaginable. The shock length/stroke deal on a Bullit varies depending on several factors--what size fork you're using, geometry preferences, and the type of riding you do.

The OEM shock from '99-'02 was the 7.875 X 2.25 that produced 5.8" of travel. The most popular size that people have swapped into those year frames is the 8.5 X 2.5 which yields 6.5" of travel. You can put a 2.75" or 3.0" stroke model in various lengths on these frames, but it usually requires drilling the frame, and I wouldn't recommend it unless you're a seriously deranged tinkerer...LOL! :D The 8.5 X 2.5 model is a straight bolt-in. The '03 and later models also came with a different shuttle which has a slightly kicked up position which most people feel softens the final stroke of the shock...generally a good thing. This shuttle fits all models.

My opinions on rear shock size are this: If you run a 5" fork with a short axle/crown size, the 7.875 X 2.25 may be a little better setup. If you run a taller 5" fork or longer travel fork, then the 8.5 X 2.5 model is usually better. Surprisingly at least a couple of air shocks work very well on the Bullit--the DHX-Air, my first choice, and the Manitou 4-Way Air. Most decent coil shocks work quite well on the Bullit too. Is your decision based more on economic issues (cheaper) or are you looking for top performance. BTW, not to SPAM you here, but since you asked, I have a like-new 8.5 X 2.5 Fox RC that I used on the '99 model pictured here. The Progressive 5th Element shock came out right after I bought this shock, so of course, I had to have a new 5th. :rolleyes: This shock has less than 10 hours on it. PM me if interested. I've used DHX coils, a Cloud 9, 5th coil, DHX-Air, 4-Way Air, Float R, and Vanilla RCs on my Bullits. Just about anything will work, but some are better than others for sure.
 

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Making the dhx air less linear...

Hi TNC,

This was written by another poster BLUR'b and I thought he had an interesting and relevant tuning method that you could try.

He wrote......
When the official Fox centre was dealing with the DHX-Air on the rebound issue they called to ask what I thought of the ride and feel of the shock. I replied that on the whole it was great although it did seem to race through its travel in compression. They suggested that to help prevent this they could fill the void between the inner and outer sleeves on the main air chamber with grease, thus reducing the volume of the main air chamber. Well they did this and what a transformation!! The shock now feels completely balanced. I'm able to run less pressure but still achieve a third's travel as sag. The shock just seems to be able to hold the bike up better through the full range of its travel (if that makes any sense!!??). I'm 188lb, 6'1'' tall and ride a large Nomad with Fox 36 RC's up front. The rear shock has 240 psi in main chamber, 150 psi in boast valve, bottom out set al the way out as is the pro-pedal and rebound set at 8 stops out from full on. The forks are running at 70psi with little to no slow / high speed compression.

Cheers,
Alan
 

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carpe mañana
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GspotRider said:
Hi TNC,

This was written by another poster BLUR'b and I thought he had an interesting and relevant tuning method that you could try.

He wrote......
When the official Fox centre was dealing with the DHX-Air on the rebound issue they called to ask what I thought of the ride and feel of the shock. I replied that on the whole it was great although it did seem to race through its travel in compression. They suggested that to help prevent this they could fill the void between the inner and outer sleeves on the main air chamber with grease, thus reducing the volume of the main air chamber. Well they did this and what a transformation!! The shock now feels completely balanced. I'm able to run less pressure but still achieve a third's travel as sag. The shock just seems to be able to hold the bike up better through the full range of its travel (if that makes any sense!!??). I'm 188lb, 6'1'' tall and ride a large Nomad with Fox 36 RC's up front. The rear shock has 240 psi in main chamber, 150 psi in boast valve, bottom out set al the way out as is the pro-pedal and rebound set at 8 stops out from full on. The forks are running at 70psi with little to no slow / high speed compression.

Cheers,
Alan
That makes perfect sense. By reducing the size of the air chamber you shift the knee of the air spring curve to the earlier section of the compression stroke. You also help increase the final pressure at the end of the stroke, so you aid in the bottomout control. I've been preaching the gospel at the Turner forum, but noone has tried this, yet. It would work very well for the high compressoin ratio bikes like the 6 Pack. The only downside to this is that you increase the force stored in the spring, so you create a more violent early part of the rebound stoke, which could make for somewhat uncontrolled landings off of big drops.

_MK
 

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noMAD man
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Discussion Starter · #11 ·
Whoa!

GspotRider said:
Hi TNC,

This was written by another poster BLUR'b and I thought he had an interesting and relevant tuning method that you could try.

He wrote......
When the official Fox centre was dealing with the DHX-Air on the rebound issue they called to ask what I thought of the ride and feel of the shock. I replied that on the whole it was great although it did seem to race through its travel in compression. They suggested that to help prevent this they could fill the void between the inner and outer sleeves on the main air chamber with grease, thus reducing the volume of the main air chamber. Well they did this and what a transformation!! The shock now feels completely balanced. I'm able to run less pressure but still achieve a third's travel as sag. The shock just seems to be able to hold the bike up better through the full range of its travel (if that makes any sense!!??). I'm 188lb, 6'1'' tall and ride a large Nomad with Fox 36 RC's up front. The rear shock has 240 psi in main chamber, 150 psi in boast valve, bottom out set al the way out as is the pro-pedal and rebound set at 8 stops out from full on. The forks are running at 70psi with little to no slow / high speed compression.

Cheers,
Alan
I was gone this weekend and just saw this. The principal makes sense. However, I've been pretty happy and impressed with the DHX-Air as is...once the tuning nuances got shaken out here on the forum. At this point I'm running 180psi in the main and 160psi in the boost valve...boost valve chamber shut all the way down and Propedal completely off or open. Now when the Nomad arrives, I'll have to start over, but at least with a little more knowledge about the shock's operation. Who knows...on the Nomad, I may have to try something like this described mod if I can't get optimum performance through the conventional tuning methods. Thanks for this info.
 

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Meh.
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TNC said:
Yeah, I've had a 4-Way Air for quite awhile running on another Bullit, and I reported the differences last month between theses two shocks. Basically the 4-Way is a firmer shock all the way around but still very good. I have an '00 Enduro Big Hit, but I've never run a stable platform shock on it...hasn't seemed necessary. It runs a simple Cloud 9 shock and works great. 33 lbs. on a Bullit isn't too hard to achieve, especially with a set of CrossMax XL wheels and running 2.5 Weirwolfs in tubeless setup.
Why does it look like there are even more spacers stacked on top of your stem in the DHX photo than the Swinger 4-way photo?
 

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noMAD man
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Discussion Starter · #13 ·
OMG!...it shrunk!

XSL_WiLL said:
Why does it look like there are even more spacers stacked on top of your stem in the DHX photo than the Swinger 4-way photo?
LOL!...Well, actually you take this thing called a hacksaw and rub it back and forth really hard on the alloy steerer tube of the fork, and before you know it, a piece of the steerer will actually fall off. :D Seriously though, the pic with the longer steerer is the first test of the fork and shock. I usually take a couple of rides with an uncut steerer to make sure where I want the stem/bar height to be before I cut the fork...especially on such an expensive fork. The pic with the 4-Way Air is during the time that I sent in the DHX when it was "stuck down".

Or...I accidentally dropped one of my Viagra tablets into my steerer tube and...well...you know. :D
 

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Meh.
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TNC said:
LOL!...Well, actually you take this thing called a hacksaw and rub it back and forth really hard on the alloy steerer tube of the fork, and before you know it, a piece of the steerer will actually fall off. :D Seriously though, the pic with the longer steerer is the first test of the fork and shock. I usually take a couple of rides with an uncut steerer to make sure where I want the stem/bar height to be before I cut the fork...especially on such an expensive fork. The pic with the 4-Way Air is during the time that I sent in the DHX when it was "stuck down".

Or...I accidentally dropped one of my Viagra tablets into my steerer tube and...well...you know. :D
I was under the impression that the DHX was the newest build, and with the DHX, the steerer is longer.

Oh, just read what you typed again. I think I understand now.
 
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