Fox 32 FIT cartridge and RP23 With Boost Valve - Interbike 2009

Sep 28, 2009
by Mike Levy  
Fox Racing Shox has made some important changes throughout their suspension lineup for 2010 by expanding some of their proven technology into other platforms. The 32 mm series of forks will be equipped with the downhill proven FIT damping cartridge for more control and reliability, and the revered Float RP23 should become even more capable with the addition of Boost Valve technology. Inside we'll take a closer look at both of these systems and what they mean to the rider. Put on your learning hat as there are two great videos to watch inside!

Read on...

Fox FIT RLC Cartridge Overview

For the upcoming 2010 season Fox has equipped their 32 series forks with the proven FIT damper system. Previously only available on Fox's longer travel offerings, the FIT damper is designed to offer a more consistent damping over rough terrain, as well as added adjustment range and a slightly lighter overall fork weight. While Fox's original open bath platform can still be found on certain models, the FIT damper is their premium system and will add another level of performance to the 32 mm forks.

Interested in the new 32 mm FIT equipped forks? Watch the video for more information!

Views: 12,920    Faves: 7    Comments: 3

2010 Fox FIT RLC damper as found in select 32 series forks

The FIT damper is a sealed cartridge, effectively separating damping and lubrication oil. The benefits of going this route are two fold: One, because the damping oil no longer does double duty as lubrication oil, service interval periods should be greatly extended. Two, the opportunity for the oil to suffer from cavitation (foaming) is reduced due to the element of air in an open system being removed from the equation. This is where the FIT bladder plays a major part, compensating for the oil displacement as the damper rod cycles through its stroke. An added benefit of using a bladder instead of a floating piston is reduced friction as one more seal is removed from the system.

FIT RLC damper body, bladder on far right

The FIT cartridge sits inside the right fork leg and is upside down when compared to some other designs. The rebound dial is now found at the bottom of the fork leg, low speed compression adjustment and lock out force are both located at the fork crown. The FIT RLC damper has a wider low speed compression range that can be dialed in to give a super active to firm platform, and anywhere in between.

Rebound adjustment dial

• FIT RLC and RL (OE only) can now be found on select 32 mm Fox forks for 2010
• RLC adjustments include rebound, low speed compression, lock out and lockout force adjustment, air pressure
• RL adjustments include rebound, lock out, and air pressure
• Total weight loss of 72g. (FIT RLC equipped fork)

Inside Fox's 32 mm fork and FIT cartridge

The 32 mm series of forks has two axle options to pick from, traditional QR dropouts and the newer 15 mm QR system. A tapered steerer is also available for the same riders who would consider the 15 mm QR lowers.

FIT RLC cartridge exploded view, note bladder at the top of the fork

Have a look at Fox's 32 F-Series fork featuring the new FIT RLC damper cartridge.

Fox Boost Valve Overview on the RP23

Fox's Boost Valve technology began life on their DH dampers and now can be found on the venerable RP23 shock for the 2010 season. Although Boost Valve is utilized through the entire stroke on the RP23 (as opposed to the last 1/3 on the RC4), one of the obvious benefits of the Boost Valve is added control at the end of the stroke. As small as the RP23 is, it is poised to become one of the most versatile shocks on the market.

Watch the video and let Nick from Fox Racing Shox explain the benefits of the Boost Valve on the RP23

Views: 7,719    Faves: 3    Comments: 0

Fox RP23 with Boost Valve

The Boost Valve found on Fox's RP23 does much more than just control the shock's ending stroke, it is actually in use throughout the entire stroke. The position sensitive damping of the Boost Valve system can be taken advantage of at the beginning of the stroke to gain higher pedaling efficiency on bikes that could benefit from a firmer feel without having to resort to flipping the ProPedal lever. As a rider that deplores having to fiddle with levers, I look forward to having a go on this new RP23.

Exploded view of Boost Valve equipped RP23 behind glass

• Boost Valve within the Float family can only be found on the RP23
• Position sensitive damping comes to the RP23
• RP23 adjustments include ProPedal level, ProPedal on/off, rebound, and air spring pressure
• RP23 is available in many sizes between 5.5" x 1" stroke to 8.5" x 2.5" stroke, and many sizes in between

RP23 with Boost Valve detail

Fox 32 series FIT RLC cartridge and RP23 with Boost Valve technology

More info on Fox's Boost Valve technology as used on the RP23.

Go to to see all Fox's suspension products!

Mike "Kakah" Levy


  • + 36
What I really want is a 180mm 36 series. Stop jiggling about with the dampers already and make a bloody 7" SC fork for crying out loud! Can't you hear the requests coming from the consumer market?

  • + 15
 i'm with you jbirimen, something like a single crown version of the 40 with slightly reduced travel would be awesome. GET ONTO IT FOX!
  • + 21
 I want a 36 float or 36 van with 180mm of travel.

Manitou is not offering such product with 1.1/8 steer tube, Marzo's are heavy as s*** and a bit unreliable latelly, and I would never risk a Totem after what I saw with the ones from some mates of mine (like, even the stantions got broken, and the guys are fairly light riders). Nothing wrong with RS (I have a boxxer) but the toten doesnt seem - to me - to be "there" yet.
Further more, I have a 36 float and the thing feels great on my 6 or so inches bike. I want a 7" fork - from FOX - for my heavy duty bike... and as far as I can see over the web, so does half the world.

C'mon Fox, chop chop...
  • + 3
 It is comming... just be patient!
  • + 6
 I hope its coming... But the other 7 or so inch travel forks out there, as such mentioned, have serious design drawbacks that may not be a fault of the manufacturer but a fault of the design; too many sheering forces acting on the upper crown for instance. Maybe fox has refrained from high travel single crown forks to avoid having, god forbid, one of their amazing suspension designs deemed 'flawed'.

personally, their current line-up may as well be the best on the market and still sells out every year. If i were them, i would also be hard-pressed to add another.

of course Fox engineers are crazy awesome at designing flawless product... Maybe at least one attempt would be nice.
  • + 1
 yea i agre with sjones the forces on the forks are big but they cold make a try if not then stick to the 6inch forks
  • + 1
 I believe that there is going to be a 170mm 36 coming stock on the new Trek Scratch, so they're nearly there.
  • + 1
 yea but u cant buy them u can buy them with 160mm of travel
  • + 1
 im glad im not the only one wishing fox would make a 7in fork, i have no idea why they dont, fox would steel so many marzocchi and rockshox supporters...lets hope for 2011!
  • + 1
 jbirimen true man id love a 180mm float rc2 id scrap my totem for such a fork bring it on fox
  • + 1
 The question is whether a 7" single crown fork is a good idea at all... furthermore the lower legs of 36 are incapable of hosting a 180mm travel, they would have to make a completely new fork AND the 36 does it's marvelous job with the travel it currently has.
  • + 1
 true WAKIdesigns they doo a marvelus job... but it doesnt hurt to try...
  • + 1
 im sure a 36 could push an extra 20mm. we have seen many forks under 36mm stanchions with 180mm travel or more. and a 7 inch single crown fork was the best thing since sliced bread my freind
  • + 1
 deberguknottignham - I was talking length, not diameter... travis SC had 203mm at 34mm stanchions. Well all 7" forks we see now on the market are unreliable, expensive as hell, weigh nearly as much their double crown friends (with sacrificing stiffness and strength) For me the only prop for long travel SC's is the X-Up clearance and no risk of denting the side of the frame near the head tube... the last good and reliable long travel SC fork was Marzocchi 66 from 2006 (apparently installed in my bike Smile )
  • + 1
 i prefer singles to daul crown not just for being to x-up you get alot more turning circle outta your bike and i just prefer the feel in general. ive had many pairs of 66s and yes they had the rep for the best single crown im now running a totem and a fox float and both are reliable forks in the rite hands
  • + 0
 deberguknottignham- do u ride DH or freeride? bcs the dh scene needs more stiff forks thats the dual crown no single crowned fork is stiffer than a thin single crown so yor riding style is inportant and wat u prefere...
  • + 1
 no you dont need a dual crown fork to ride dh. a 40mm totem or a 36mm float can handle anything that me or you could throw at it
  • + 1
 u can but its not made for dh i have a dual clamp fork and have no problems cornering even the tightes stuff
  • + 1
 i did not say that you cant corner with daul crown forks the fastest riders on the planet use them. i just prefer singles and they are more than capable of preforming well in the gnarlyest dh
  • + 1
 yea they can but nothing does the job better than a dual clamp for dh
  • + 1
 "I believe that there is going to be a 170mm 36 coming stock on the new Trek Scratch, so they're nearly there."

This is not true. The 2010 Trek Scratch models have 160mm travel Float and Vanilla 36 models (Scratch Air 8 and Scratch 9, respectively).
  • + 1
 Yes, I am. I work at a Trek dealer and the parts specs are already online for the new bikes, both the consumer and dealer-only sites show 160mm of travel on the bikes.
  • + 1
 Allow me to quote the Trek dealer-only website for the specs on the Scratch 9: "Fox 36 Vanillia RC2 w/Fit cartridge, coil spring, preload, hi/lo compression, rebound, alloy E2 tapered steerer, 20QR, 160mm 15.5/17.5" blue; 19.5/21.5" green spring"
  • + 1
 Demn, Seraph, you ruined the fun again: we already heard that the single crown forks are better on gnarliest DH course than the dual crowns (apparently we have been presented with example pictures of situations where even RS Pike would be enough) Perhaps if you wouldn't interrupt we could hear that SCs are 20% stiffer, 15,5% stronger and Steve Romaniuk rides them so its good.
  • + 1
 Just doin' my job.
  • + 1
 damn, i got owned
  • + 8
 as always pushing the bar, nice one!
  • + 20
  • + 14
 without scientists, bikes wouldn't even exist!
  • + 9
 thank god someone stayed for the science classes! someone had to do it so we can ride harder! thanks!!
  • + 2
 chyea couldnt agree any more actually
  • + 4
 you sure you aren't oversimplifying it?

i wonder what the team of designers and engineers at fox would have to say to that.
  • + 3
 it's not that bad. any true expert in any field will be able to break things down into layman's terms!
  • + 1
 I think you guys mean "physicists."
  • + 1
 i hate the fact that the cool red rebound knob is not on the top anymore! for me the best looking thing about fox are the "blue/red" knobs on the top)
  • + 2
 I've been running a 2010 Fox RP23 on my bottlerocket for a couple of months and it rocks, takes everything i've thrown at it from DH to jumps - people need to adjust there view about air shocks, they are here to stay and it'ss all goood!
  • + 1
 Maybe Fox is waiting till the market is thirsty enough for its 180 mm product. I personally think it had been designed and prototyped.

But business men want to thirst up the riders then introduce their product when theY would be sure to swallow up the market and other competitors like Totem-Domain-66-Travis and….
Production is more into money than into demand and performance.
  • + 0
 i dot want a 180 mm 36...
i want a single crown 40!!!!
ut really, even after the abuse i threw on to my 40, and after the mild maintenace it needed, it still out performed athe other forks ive used, ( Marz. 888 WC and boxxer), and i can service my forty in my living room in like fifteen minutes! it stiff as all hell (too stiff? bring it i say)
every fork needs seals after a few months of getting rad!
the 40 can be reduced to 170 or 160 if thats all you want.....
i like fox, and they fave tsken better care of me as a rider, then any other brand cared too,
and in the end, that is what makes the diff....
marso left me hangin for over two months on a rear shock that was for racing!!!
and RS is soooo close to dialing the totem.. but still.....
fox is where i live.
  • + 1
 The Rock Shox Totem is basically a single crown Fox 40.
  • + 1
 With the Lyrik moving to 170 I am shocked (good word?) they havent moved the 36 to 170mm. My guess is that it aint far away.
  • + 1
 fox are coming out with a 180mm 36 option soon.
  • + 1
 as I written above, the lower legs of 36 are too short to get 180mm of travel (at least without making the bushing spacing like 1cm... which would make it "sort of flexy") Lyrik has at least 20mm longer lowers therefore it was possible to put 10mm more into it. The answer is: they need a completely new fork
  • + 2
 I happen to know for sure that a 180mm fox 36 will be coming out next year!
  • + 1
 but i guess it will come with the new lowers Wink
  • + 1
 It's innevitable that Fox will release an 180mm travel fork. They have everything else anyway.
  • + 0
 my new dhx 4 air has just come with the boost valve and i was wondering how much psi should i be putting in there for plush dh and also in the main shock body? wall me please
  • + 1
 Go to and check out the tech section.
  • + 1
 i have a 2010 rp23 with boost valve on my st4 Big Grin
  • + 0
 that is some nifty stuff, well done fox tup
  • - 1
 if they made a 180mm it would be super expensive. get a 66 or a totem.
  • + 2
 it would be worth it, and damn reliable too, compared to totems that always leak and 66's that have a different problem for every fork.

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