Fox Shox DHX Air 4.0 Rear Shock

3.15/5 (13 Reviews)
Weight : 425 grams


Product Description

  • Position-sensitive Boost valve
  • Adjustable ProPedal Technology
  • Adjustable air spring pressure
  • Rebound adjust


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Reviews 1 - 13 (13 Reviews Total)

User Reviews

Overall Rating:5
Value Rating:5
Submitted by Mountainfrog a Downhiller from Phoenix, Arizona

Date Reviewed: April 1, 2011

Strengths:    This shock works! Set-up is totally different from most shocks, run more air! Perhaps too little air is the reason some people have stuffed this shock. Easy set up, doesn't leak. Pro-Pedal switch easier to reach, but don't need to use.

Weaknesses:    Sticky skin too thin, cable wore right through it. Damping knob a little difficult to get to but once dialed in not a fuss.

Bottom Line:   
This shock is well balanced to the Fox Float fork. I weigh 170lbs and run 85-90 psi up front and 190 to 200 psi in the rear with 175 in the Boost valve. This set up works super smooth and to date I've experienced nothing but pleasure while ridng this bike. This is my fourth Reign and each successive bike seems to come with better working Fox products. I actually prefer this shock over the RP23, which is a great shock! You must run more air than conventional set-ups in order not to blow through your travel and stuff it.

Expand full review >>

Favorite Trail:   Jedhi

Duration Product Used:   2 Years

Purchased At:   Giant Bicycles

Similar Products Used:   I've had Manitou SPV, Fox RP3, and RP23 on my last three Reigns.

Bike Setup:   '09 Giant Reign 1, upgrades include XO rear derailer and shifters, bash guard, 90mm stem, Easton Haven wheels.

Overall Rating:1
Value Rating:2
Submitted by TXTony a Cross Country Rider from Ft Worth

Date Reviewed: March 26, 2011

Strengths:    It makes the bike look tough(Enduro)...it holds air.

Weaknesses:    I have had this shock on my bike since 2006 and like others it stuck down on its third ride..had to be rebuilt...over the years I have left my Enduro sitting because of this shock and opted to ride my other bikes..the shock is like a pogo stick..when it gets going it really pogos..propedal on this thing is useless..it works reallly good if the trail is pointed down...all the time..anything else it makes the bike perform like some cheap out of control FS bike.

Bottom Line:   
I am going to replace this shock on this bike and see if I can not bring the old girl to life...I feel I have missed what this bike is really capable of and am going to put a Monarch Shock on it from Push Industries

Expand full review >>

Favorite Trail:   North Texas

Duration Product Used:   More than 3 years

Purchased At:   LBS

Similar Products Used:   Other Fox products

Bike Setup:   2006 Specialized Enduro..

Overall Rating:5
Value Rating:5
Submitted by motoman373 a Weekend Warrior from fort bragg, ca

Date Reviewed: November 27, 2010

Strengths:    compliments bike rear suspension design, feels plush, looks well crafted.

Weaknesses:    havn't had any problems yet

Bottom Line:   
sounds like some peple have had some unfortunate problems with their shocks, sounds like bike shop mechanics may be giving some lame excuses for improperly setting up the pressure from the shop or maby not. mine works good though with good understanding of suspension has easy set up. i give it a thumbs up for taking the abbuse i give it

Expand full review >>

Duration Product Used:   3 months

Purchased At:   came on my bike

Similar Products Used:   for rp23

Bike Setup:   cannondale carbon moto 3

Overall Rating:5
Value Rating:5
Submitted by Knotzykiller a Downhiller from surrey

Date Reviewed: August 27, 2009

Strengths:    Solid, has`nt Let me Down...

Weaknesses:    ?

Bottom Line:   
This fork came with my bike and I have used it many times for aggresive cross country and had it up to Whistler 4 times beating on it with jumps and just started on the drops. This shock has not let me down but I oil the piston stem before every ride and also check the air pressure before every ride as per my bike mec... I came on line to find out how to properly set up the air chamber and spring, maybe 1st set the spring then the air chamber??? I have a 450 LB spring and might beef up to a 550 LB spring, I`m 170 LBS. Again I have no idea how to properly set up the air chamber but I always rode with 170LBS in the chamber maybe that`s to much?

Expand full review >>

Favorite Trail:   Frieght Train- A-line

Duration Product Used:   1 Year

Purchased At:   South Shore Cycle

Similar Products Used:   None

Bike Setup:   Gary Fisher King Fisher1 2006

Overall Rating:4
Value Rating:4
Submitted by fred6ft a Downhiller from wales

Date Reviewed: November 22, 2008

Strengths:    good strength and very versatile. good adjustability

Weaknesses:    none yet

Bottom Line:   
shock has had a lot of bad rap and all in all, this is not a bad shock. its adjustability is its strength and can be set to any type of ride you are into. the propedal is amazing. i actually forgot to switch it off on the way down, but it still gave me all the travel. shock is so light and even though this is the first full day of using the shock, i did not find any trouble setting the shock up. it is so plush and i dont have much bad points on it.

i way 180 pounds and got it set up at 210 psi in the main chamber and 170 in the top chamber.

the only reason why im not giving it 5 chilis is cause ive not done much riding with it yet.

Expand full review >>

Favorite Trail:   mountain ash

Duration Product Used:   Less than 1 month

Price Paid:    $250.00

Purchased At:   ebay

Similar Products Used:   marzocchi

Bike Setup:   mongoose teocali, marzocchi z1, fsa moto exo, halo combat on spindoctors and sram

Overall Rating:4
Value Rating:5
Submitted by b_maiden a Weekend Warrior from Brisbane AUSTRALIA

Date Reviewed: October 10, 2008

Strengths:    Cool design and very robust casing. Looks very solid and feels solid in addition to adjustment options (Pro pedal)

Weaknesses:    It took a while to get the setting right. It does require more psi than I was expecting (approx. 175 psi) for my body weight I have never set my rear shock as much as that.

Bottom Line:   
I have been reading the above comments/reviews and I will be honest, I got a bit worried that I bought an equally nasty shock in my bike. So I did the only thing I can to test it... ride the bloody thing. Of course firstly I set it up the best I can (sag meter, pro pedal etc.)realtive to my weight. I then took it to some good xc/downhill trails which involved creek crossings, rocky downhills, smooth rolling dh jumps and over trees and so on .... BULLET PROOF. NO leaks, no locking, no problem. Got lucky? Maybe....

Expand full review >>

Favorite Trail:   Turning Japanese (Daisy Hill)

Duration Product Used:   6 months

Price Paid:    $1.00

Purchased At:   Ebay

Similar Products Used:   Specialized rear shock on Stumpjumper Comps 2008's. Sorry I dont know the actual model/series.

Bike Setup:   2006 Specialized Enduro Elite original spec.

Overall Rating:5
Value Rating:5
Submitted by SRS a Weekend Warrior from Honolulu, Hawaii, USA

Date Reviewed: February 15, 2008

Strengths:    Great pro pedal feature. Simple dials. Nice volume and good rebound.

Weaknesses:    None really. Mybe the boost valve is hard to get to.

Bottom Line:   
Some people may not be setting this shock up properly as I hear stories about being "stuck down". It is my opinion only that one should never set a DHX Shock based on a persons body weight. I set mine up using the 25% sag rule and it results in more air (psi) in the shock. When it is filled right, the shock is amazing. It really enhances my Rocky Moutain Slayer. This is a large high volume chamber, so the body weight rule may not work.

Bottom Line..............good shock for over a year.

Expand full review >>

Duration Product Used:   1 Year

Bike Setup:   Rocky Mountain Slayer SXC70

Overall Rating:3
Value Rating:4
Submitted by Ben a Weekend Warrior from Sydney, Oz

Date Reviewed: October 21, 2007

Strengths:    Good shock, nicely adjustable, takes everything i can throw at it, platform works well

Weaknesses:    My shock pump is a bit hard to maneuver into the boost valve, but that's the pump, not the shock. Takes a while to get dialed in correctly.

Bottom Line:   
Well, it seems that MTBR has a bad case of the "only review it 'cos it broke" going on. My shock has been fine, i stuffed it up by putting the shock pump on too hard to the main reservoir, but it was a $5 fix for some new valve cores and a core tool, now perfect. It takes a bit of riding to get the sag, rebound and bottom out (boost valve) set, but once you have, it takes everything you can throw at it and more. The lack of "bottom out" control doesn't matter since the boost valve does the same thing - just run the shock with 175psi in the boost valve and it will eat everything without bottoming out. Propedal seems to work quite well too - with 175psi in the boost valve, even standing and mashing the pedals hardly bobs at all.

Expand full review >>

Duration Product Used:   3 months

Price Paid:    $2.00

Similar Products Used:   Vanilla R

Bike Setup:   Norco Six 1 '07, stock except for Syncros BHT tyres and Wellgo pedals (just didn't like the DMR V8's)

Overall Rating:1
Value Rating:1
Submitted by Frank a Weekend Warrior from Alberta, Canada

Date Reviewed: September 16, 2007

Strengths:    Propedal works well you can limit the peddle bob with this ajustment.

Weaknesses:    I am disapointed with this product. First time ever I buy an expensive bike. Assumed that all components would work flawless. Mistake the shock id leaking oil from the rebound adjust button, the dealer supposedly sent it back to get rebuilt but the didn't fix the problem. Can you guess the shock is still leaking and from the same location. You would think that if you bought a high end bike the store or manufacturer would go out of their way to make sure all components work probably before selling them. Save your money and buy a Walmart throw away, you'll be happier you did!!

Bottom Line:   
Crappy rear end on an expensive bike. And After being rebuilt to repair the leak the bike shock still leaks. I wonder, did it really get rebuilt??

Expand full review >>

Favorite Trail:   Rabbit Hill

Duration Product Used:   Less than 1 month

Purchased At:   United Cycle


Overall Rating:1
Value Rating:1
Submitted by Terry a Cross Country Rider from Creston, BC, Canada

Date Reviewed: June 9, 2007

Strengths:    ummmm........ nice colour????? Sorry, that's all I could come up with.

Weaknesses:    I just got the bike back from a warranty job on the shock because it stuck down. I guess I have about 4 or 5 rides in now since I got it back and it happened again. I was 25 km's out and had to gingerly ride it back so I didn't rip my tire to shreds or pull off the front derailer. (Enduro riders will relate) I was pissed. I'm sending it back but this will be another 2-3 weeks off of riding because of this useless piece of junk.
Thats twice in less then 5 months of riding.


Bottom Line:   

Bottom line? Garbage. I hope someone from Fox reads the reviews on this model and notices the theme. If you're buying an enduro ask them to switch it out to something else. Spring perhaps?

I don't grunt up a mountain on this pogo stick of a shock, with its negligible propedal action, to waste one of my two measly days off per week, to do 20 metres of the best cross country trail in Nelson BC (Paper bag for those interested), only to have my recently rebuilt shock break down AGAIN.
Sorry folks, I just got home from this and I'm fired up.

Expand full review >>

Duration Product Used:   1 Year

Purchased At:   came on the bike.

Similar Products Used:   My walmart bike with the rear suspension lasted years longer then this thing has.


Overall Rating:1
Value Rating:1
Submitted by gt a Cross Country Rider from ketchum, idaho

Date Reviewed: March 23, 2007

Strengths:    fox product,

Weaknesses:    heavy, useless piggy back reservoir. leaks oil out out adjustment knob.

Bottom Line:   
ive had the bike two months and its never been on dirt. (its middle of winter) i ride it to work and back daily. (about a mile on pavement). apparently from my bodyweight alone, the shock compressed and stuck. it would not return. i thought it was just low on air, but that wasnt it. the bike shop said it blew an internal seal. how, i dont know. if this is fox's finest free ride, dh shock, they need to go back to the drawing board. i am already looking at other options (rock shox pearl). the plus is, fox is good about repairing the shock, but im guessing it will be broke again after my first ride. maybe just a lemon. i will write another review in a couple months

Expand full review >>

Favorite Trail:   fisher creek

Duration Product Used:   3 months

Purchased At:   came on specialized enduro

Similar Products Used:   fox float rl (it was flawless for 5 years)

Bike Setup:   enduro elite

Overall Rating:1
Value Rating:1
Submitted by mike dunphy a Cross Country Rider from Buena Vista Co USA

Date Reviewed: March 10, 2007

Strengths:    Looks Nice

Weaknesses:    Leaking oil on the first ride. Nothing major as far as hits. Leaking out of the rebound adjustment. New bike from Rocky Mountain. 2 week wait from Fox so they can rebuild the piece of crap.

Bottom Line:   
Nice piece of crap. Its good to know that I will probably need service on this shock again in the near future. Fox will not be a consideration in the future if they send out product like this. The shock was setup before the first ride. Sag, pro pedal etc.

Expand full review >>

Favorite Trail:   Monarch Crest, Colorado Trail

Duration Product Used:   Less than 1 month

Similar Products Used:   Came on the bike.

Bike Setup:   Talus 36 on the front xt, jucy 5, race face, mavic

Overall Rating:5
Value Rating:1
Submitted by tony a Cross Country Rider from saginaw

Date Reviewed: October 31, 2006

Strengths:    It is smooth when they work.

Weaknesses:    It stuck on the fourth ride.

Bottom Line:   
After only four rides on the bike the shock stuck. I had to have it rebuilt. I am not sure how it will do on the long haul but one would think it would have held up better than four rides. The rides were XC trails nothing extreme. I am thinking for this type of bike a coil shock may be they way to go. If the shock goes again I will be replacing it with something else, not a Fox.

Expand full review >>

Favorite Trail:   anywhere there is dirt

Duration Product Used:   3 months

Price Paid:    $2600.00

Purchased At:   LBS

Similar Products Used:   RockShox Sid. Never a problem

Bike Setup:   This shock came on my 06 Enduro.

Reviews 1 - 13 (13 Reviews Total)

Review Options:  Sorted by Latest Review | Sort by Best Rating


Where is bottom of DHX Air 4.0?

I'm a little confused about where the "bottom-out" is of the [URL="http://www.ridefox.com/fox_tech_center/owners_manuals/09/Eng/Content/Rear_Shocks/DHX_Air_40.htm"]DHX Air 4.0[/URL]. Is the bottom the absolute end of the shock body? Or is the bottom some pressure-limit say, an inch above the botto ... Read More »

fox dhx 4.0 air service/rebuild

couldn't find a clear answer doing a search, what can i expect to pay for a full rebuild/servicing? can this be done at home?Read More »

dhx air 4.0 service

i am noticing a "thump" in my dhx air 4 shock. its typically when my propedal is on. It also blows though travel pretty fast. Do you have any recommendations what the thump is or tuning ideas?Read More »

dhx 4.0 air bad rap; I figured mine out

dhx 4.0 has massive bad reviews about bottoming out and i had the same problem at first. i found when you pump up the boostvalve propedal you lose 80 to 100 lb when detaching the pump. If you assume your only gonna lost 10 lb like pumping up the main :nono: i pumped it up to 250lb just to get 170 w ... Read More »

2010 Reign Fox DHX air 4.0 Rebound stuck/jammed

OK, i hadn't moved this since having the air sleeve serviced. I figured i wanted two more clicks of rebound, but i could not move it. The only way i can turn the red rebound knob, clockwise or counter, is to jam an allen wrench in there and push relatively hard. A snapping click occurs every 7th ... Read More »

Read More »



 

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