Prototype FOX DH Shock - 2013 World Champs

Aug 27, 2013
by Mike Levy  
FOX prototype RAD DH shock

World Champs is always a special race where teams and sponsors go all out to give their riders any and all advantages possible, and because of that it is also the setting where we see a number of projects debuted that have clearly been in the works for quite awhile. This year's venue at Pietermaritzburg, South Africa, is no different, with the relatively smooth track likely making for some very special setups - we expect riders to be on anything from full-out downhill race bikes to six inch travel all-mountain rigs come race time. Two riders who we anticipate will choose to ride the former, though, are Trek World Racing's Brook McDonald and the Syndicate's Greg Minnaar, with Brook's Session 9.9 and Greg's V10 sporting very special FOX shocks that are products of FOX's RAD (Racing Application Development) program.

The RAD program has been responsible for a number of the products that we first saw on the bikes of very select World Cup racers, with some of them eventually hitting production - the current DHX RC4 shock, for example - and others not making the cut - a la the prototype inverted DH fork that was eventually cancelled. While FOX declined to comment on the unnamed shock, it is clear that it looks nothing like a DHX RC4, with some major differences that set it apart, most notably the shock's wildly different adjuster dials and steel shaft. Although we are forced to speculate at this point, there appear to be four separate dials, with stacked compression and rebound knobs that control both low and high-speed damping. The anodized red dial likely controls the low-speed rebound, with the large hollow nut above it being used to alter the high-speed rebound setting. We're guessing that the same can be said of the anodized blue compression adjusters right next to it, making this prototype RAD shock a four-way adjustable unit that likely uses completely separate circuits for compression and rebound damping duties. This is supported by what appears to be two plugs just below each dial that would give FOX access to each of the circuit's respective check valves. Again, this is pure speculation at this point, but it would make sense that FOX would pursue a shock design that allows for more external tuning. While the current DHX RC4 uses a large blue dial at the end of its piggyback to adjust its volume, this prototype shock appears to make use of a much
more svelte system that probably accomplishes the same task. Much like a fork's preload adjuster, this new dial looks to sit flush with the piggyback body, with internal threads that likely move the position of a volume-changing puck, allowing the rider to adjust how the shock ramps up. The layout looks much more discreet than what is currently offered from FOX, and it is probably lighter to boot.

FOX prototype RAD DH shock

The other major talking point is the shock's much smaller shaft that appears to be steel opposed to the larger diameter aluminum version used on the standard DHX RC4. The shaft's smaller diameter means that it will displace less oil than a larger diameter version, making for less ramp up throughout the shock's stroke. The other upside to the smaller diameter shaft would be its smaller swept seal area that would help lessen friction, especially breakaway force at the top and bottom of its stroke, as well as when it changes direction from compression to rebound. It is plausible that none of the above would have been possible with an aluminum shaft due to it being too fragile in a decreased diameter.


FOX prototype RAD DH shock

As expected, there will be a number of top riders who will run an air-sprung rear shock instead of either a DHX RC4 or the prototype coil-sprung shock discussed above, and it appears that it will be the RAD air shock that was tested during practice for the Fort William World Cup. While it certainly resembles a DHX Air shock (which is no longer listed on FOX's website, by the way), it is safe to say that it likely employs some of the design features of the promising Float X shock of FOX debuted a few months back. With much of the above being only theory at this point, it will be interesting to hear FOX's official word on both the prototype RAD coil and air shocks shown here.


Stay tuned for more from South Africa



www.ridefox.com
Photos by Matthew DeLorme


111 Comments

  • + 410
 So now small shafts are a good thing???!!!
I'm gonna go ahead and call that a win for me.
  • + 38
 You just made my day.
  • + 40
 Mrs. Nipes likes small shafts!
  • - 38
flag Lilshredman (Aug 27, 2013 at 20:27) (Below Threshold)
 That's what she said!
  • - 34
flag Lilshredman (Aug 27, 2013 at 20:48) (Below Threshold)
 New Small Shaft! Fits in any hole!
  • + 29
 Looks like Avalanche suspension and Cane Creek had it right from the get go.
  • - 17
flag oakrunbike (Aug 27, 2013 at 21:15) (Below Threshold)
 Lmao now that is in the running for comment of the year :-)
  • + 17
 ^Sorry, I don't think that was directed to you man.
Both of those look sick but I hope they suck so I don't feel the need for an upgrade.
  • - 8
flag baca262 (Aug 27, 2013 at 23:40) (Below Threshold)
 Bigbossman and Lilshredman lolollolololollolol
  • - 2
 smaller diameter shat.. cause they need to break in demo's again..
  • + 1
 if only cane creek came with a set of enduro and dh forks... they would rule the market!!!!
  • + 0
 @bliza - my first impression right away was Avalanche suspension dials ala TF tuned etc - maybe Fox have bought Avvy on board!?
  • + 2
 Small shaft because it's nothing inside Wink Hmm CCDB from FOX? And... no bottom out control so linear work Wink
  • + 1
 its a small shaft for our rear end, too.
  • + 5
 Bigbossman.. do you ever think someone hing and just not say it? Really your stupidity in unparalleled on this forum. Do us all a favor and don't speak.
  • + 1
 Something... auto correct fail lol...
  • + 129
 hmmmmm not sure a track that can be raced properly on a 6inch bike deserves to be the world champs track
  • - 17
flag MikeMarkov (Aug 27, 2013 at 18:24) (Below Threshold)
 I've only been watching worlds for 3 years now, but haven't seen anything less than a 8 inch DH bike, correct me if I'm wrong ..?
  • + 24
 timsim07 is right, it's basically a glorified high speed jump track. Proper DH is like Fort Bill or Val Di Sole.
  • + 11
 Jared graves is going to run it on his 6 inch SB66C this year.
  • + 2
 Pedaling power will trump comfort every time for the win. Get outta the barcalounger and come play.
  • - 14
flag Protour (Aug 27, 2013 at 21:34) (Below Threshold)
 I hope a 29er wins...so the big wheel haters have to shut up for awhile... and there never be World Cup tracks like this anymore if it happened.
  • + 4
 To play devils advocate, remember Canberra worlds in 09, Hill was on an SXT(6.7"), Lopes rode a Mojo(6") if I recall correctly. Graves is running a float at either 170 or 180 on the front end of his rig-It looks pretty capable and burly.
  • + 14
 Graves is supposed to be on a Fox 36 180mm. As long as the track is down hill it's still fair game IMHO. I don't think I'd care if they raced tricycles down the mountain. as long as they slay that track on the way down as fast as humanly possible, I'm a happy customer. I say use the most effective tool for the job!
  • + 4
 I think Mitch Ropelato is doing it on his enduro 29er
  • + 3
 Main reason Graves is on the trail bike is that is what he's been racing all year and that is what he's comfortable on. The track being on the smoother and pedalier side is helping that decision.
  • - 1
 @genericmk I also listened to the bike check sound byte. @dinero agreed. @woodhouse, a pic of his rig was posted in sexiest am thread, and sexiest DH thread
  • + 30
 I love worlds because all the special proto bits get brought out. So exciting.
  • + 1
 You would think with so much on the line, that the special proto bits would not be used. WChamps would be the time to stick with the tried and true, not mess around with lab queen onesie-twosies. However. I get a rise out of undercover speculative stuff like this (unlike a certain 'rumor'-based bike website) and a lot of the time we all get to see the progression from this level of proto to the new zoot stuff the following Interbike show. Its quite exciting, I agree.

Disclaimer - I bought shares in FOXF last week - everyone please buy more forks and shocks.
  • + 27
 Looks RAD.
  • + 6
 Looks like an X-Fusion Vector Air, almost exactly.
  • - 6
flag Lilshredman (Aug 27, 2013 at 20:27) (Below Threshold)
 RAD, ha ha ha...u so funny
  • + 16
 Looks like FOX is trying to play catch-up with Cane Creek and Ohlns.
  • + 2
 Similaritys with Cane Creak and Ohlins? O yea..
  • + 9
 I will not lie, I am a little wet now
  • + 4
 hahahahaha
  • + 5
 Fox is now working with Ohlins, who was working with CaneCreek to develop the Double Barrel. im not surprised to see the "RAD" shock to have similarities.
  • + 1
 First thing I thought was if fox was working with Ohlins when I saw the shaft diameter. Not surprised. Will be a good shock for sure!
  • + 1
 I didn't see that Öhlins was involved here... but they sure are chasing after both CCDB and TTX with this version.
  • + 3
 Can anybody explain why suspension companys have made a general shift towards have their adjustment knobs on the bridge between the shock and ifp. eg. vivid, ohlinus, and this new fox
  • + 6
 Because the piggyback is where the oil displaced by shaft goes, and it goes there through the bridge (obviously), so that's where you control the speed of the oil's flow.

Obviously there's more into it, this explains itself pretty well: www.produkte24.com/images/catalogs/2476/26978/ct/komplettraeder-2011-000021.jpg
  • + 2
 Cane Creek has a cool short video that illustrates how the oil moves around in said chambers say for instance on the DB Air. Check it out: www.canecreek.com/products/suspension/db-air/twin-tube-technology
  • + 2
 I have been racing dirt bikes for over 10 years and at a very competitive level in desert races, hare scrambles, enduros, Grand Prix, ect. The races are from 80-120 miles even 600+ miles. I've had plenty of sponsors and one of them being a suspension sponsor. (Ive spent endless hours testing suspension settings with multiple companies so ive learned alot about suspension) Suspension is my biggest problem, heat is a huge factor on a dirt bike, not only do you have heat from friction you have the exhaust an inch away from the resivor causing a huge problem. My later suzukis have a showa shock with an 18mm shock shaft and I've learned that it generates more heat. So I have to put in a 16mm shock shaft that's DLC or titanium nitrate coated (to help with heat) I also have to put in an aluminum piston because the stock steel piston doesn't expand at the same rate as the aluminum shock body under heat. An aluminum shaft heats up faster especially when its bigger in diameter. Fox is on target pretty much copying an ohlins TTX shock which is a good shock. Now the biggest problem that leads to instant shock fade is the conventional way of bleeding the shock by hand (it doesn't work shocks are too complex now) you have to send it in to be vacuum bled. Look it up on YouTube and watch a shock be vacuum bled. Also, every shock needs a high speed compression adjuster period.
  • + 1
 It would be cool if you could easily swap out the spring weight that controls high speed damping threshold. Is that what those plugs are under the rebound/compression adjusters?
The new set up probably has better oil flow as well. Small shaft room for more oil.
  • + 1
 Probably could. Although even if you can't, with a wide enough adjustment range and a couple of different weight oils you could definitely achieve the same thing, although it would take more time.
  • + 1
 Words from an armchair mechanic.
  • + 1
 No man I work on my suspension.
  • + 3
 Ohlins are quite the suspension whores... working with Cane Creek, Specialized, and now Fox. No doubt when you're the best everyone wants a piece of you.
  • + 0
 Now I know this has nothin to do with the shock but,,,,,,,,i think we shuold a poll on who we think will be the top 5 at worldchamps! ?ANYONE? Let me start haha, i think it will be,-minnar-mick-gee-smith- an-gwin!!! Anyone else have predictions!?????
  • + 0
 aren't all the shafts steel? I can't imagine shafts made of aluminum could be strong enough. My shock has an aluminum outer sleeve and steel shock shaft inside of it. These shock are prototypes and will look much different and cruder than the production versions.
  • + 1
 So this air shock is designed for smooth Dh tracks or basically for South Africa as every 1 slates the track and how embarrassing that a world champs maybe won on an all mountain/enduro type bike with 29er wheels on.
  • + 1
 Hopefully these air shocks will be a lot easier to adjust and fine tune then some of the older DHX Airs. Its also cool that FOX is moving towards reliability and strength again!
  • + 1
 Just because the racers are using them, it doesn't follow that they will be in production once again. Worlds is a place for one-offs, especially for shocks.
  • + 3
 This...i would calll it ''Fox Vivid TTX Barrel'' looks promissing
  • + 3
 CCDB and 2014 Vivid have just copulated.
  • + 1
 I wonder if this is a twin chamber shock like DB? If there isn't a rebound adjustment rod inside the shaft, that would explain its narrower diameter.
  • + 4
 It is indeed a twin-tube damper like the CCDB. This is evident from the fact that rebound adjusters are on the reservoir bridge rather than the shaft eyelet - this is only possible with a twin-tube design. It is also possible that this shock runs a solid piston like the original Ohlins TTX shocks, but I would bet against that. Ohlins, to my understanding, hold patents on this particular layout of damper, which means that either Fox are licensing this technology, or that Ohlins' patents are not (or no longer) valid in the USA... or more likely, that Fox have got some internal trickery going on that gives them enough novelty to circumvent the Ohlins patents.

Also worth noting is that despite what the article says, I do not believe there is any bottom out control on these shocks. What looks like a knob on the end of the reservoir there is more likely simply the machined end cap containing a nitrogen charging port, but made to look a bit prettier than a Van RC.

The shaft is steel and solid, larger diameter than the CCDB not because it needs to be for damping purposes, but most likely because of the number of bikes nowadays that come with these shock-extending yokes (such as the Demo 8, Yeti 303 etc) that have a tendency to cause breakage of many shocks' shafts. Fox 1/2" shafts have had issues with cracking through the threads inside the eyelet for years (as do Vivids) and they are well aware of this despite the recent move from the 5/8" shaft on the RC4 back to the 1/2" shafts. Using a slightly smaller diameter shaft that is solid steel instead of hollow aluminium should hopefully eliminate a lot of those issues.

As for the RC4 Air, those air cans use much larger negative air volumes than standard shocks (ie nothing like the Float X). We have been experimenting with this for about 11 months now and will have some interesting stuff to show to the public soon (including some completely new technology).
  • + 1
 Thank you for the reply. I was wondering about the control myself.
  • + 1
 @z-man, agreed, surprised to see fox not experimenting with a DLC at this level of the sport especially being under the RAD guise
  • + 2
 Really think Fox should have another go at the USD fork that would be so cool!
  • + 2
 steel shaft....im still running fox vanilla rc tf tuned 4 times.....my shocks cool again :-)
  • + 1
 hahaha, that shock will always be cool. got one sat on a super 8 in my garage. used to blow up every few days, but thats the super8s fault, not the shocks
  • + 3
 Too bad they dropped the inverted proto.......
  • + 1
 Small steel shafts for sponsored racers and BIG STEEL shafts for normal people. Seriously MTB suspension industry started to spin like a turd in airhole...
  • + 0
 big ali shafts. not steel. big shafts push more oil, which gives you more control of the damping. I'm guessing this is a twin tube design, and so doesn't need a fat shaft to displace the oil. Funny really, everyone i know prefers the dhx rc4 to the ccdb, now fox seem to be chasing cane creek. odd.
  • + 3
 cool, a fox shock with high speed rebound! so sweet
  • + 1
 If that shock is in my sunday I wouldn be able to reach the dials... Thanks but I 'll stick to my klunker
  • + 1
 If Ratboy isn't on a DH bike, the new kit of his should stay tucked away in favor of spandex.
  • + 3
 Interesting point you bring up. If skinsuits were allowed in DH, everyone would be rocking them at this year's Worlds. Instead I expect people to be running the tightest clothes they can get away with, and pinning jerseys tighter with your race number etc.
  • + 1
 σαν το ελατηριο απο κρεβατι δεν βαζω τιποτα !
  • + 2
 No mention on PB yet about the Boxxer 650B's seen at World's?
  • + 1
 well, with that adjuster so far forward of the mount, thats not gonna fit my fame............
  • + 1
 Looks like the '14 Vivid R2C2 something
  • + 0
 Ugly。。。。。。。。。。。。。。。。。。。。。。。。。
  • + 1
 it looks way to similar to there current moto shocks for me...
  • + 1
 Cane creek DB is the best air shock ever
  • + 2
 Those RAD shocks Drool
  • - 1
 Hmmm....small diameter steel shaft? What a novel idea! Sort of reminds me of the Vanilla R from circa 2002 that's thrown in the bottom of one of my tool boxes.
  • + 1
 I have a woodie, Avalanche that is
  • + 1
 Fox seems to feel the Ohlins' hot breath on their neck... POPCORN!
  • + 2
 steel is real.
  • + 1
 nice, looks thath designers will get some more space for frame design.
  • + 1
 Stay tuned..... hahaha
  • + 1
 Boneriffic shocks!
  • - 1
 no kashima???? do not want!
  • + 3
 kashima would be all but irrelevant on a shaft this small. Good for 40's and air cans, arguable for rc4 shaft, pointless on this. Not to mention extremely hard, if even possible, to apply to a steel shaft
  • + 1
 If you can't anodize it you can't kashima it. But you can DLC or titanium nitrate coat it which works just as well.
  • + 1
 aye, but i have seen some (aparrently) anodized steel stem bolts kicking about. Looks like a crap quality coating, but its there none the less. I was of the opinion that you cannot anodize steel till i saw them...
  • + 1
 They used to say the process baths used to anodize aluminum would attack and dissolve steel parts. But I guess it's something new they are coming on to..
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