For 2025, Fox has utterly redesigned their Manufacturing facility-level GRIP fork dampers with an all-new valve structure that makes them concurrently plusher and extra supportive.
With the said purpose of “Pushing Potential Additional”, the brand new GRIP SL, GRIP X, and GRIP X2 provide distinct tuning traits for 3 distinct varieties of riders. With previous generations, they’d a fork chassis (32, 34, 36, 38, 40) for each bike class. Now, they’ve a damper to personal each class, too.
Right here’s every thing you’ll want to know concerning the subsequent technology of GRIP dampers…
2025 Fox GRIP Dampers are all about Stress Balancing
The important thing buzzword on the 2025 GRIP launch was “Stress Balancing”. It’s a tuning philosophy that, due to using far more superior measurement units they’ve began utilizing contained in the fork, permits them to create strain differentials contained in the damper shaft.
I’ve spent hours speaking with Invoice Brown, Fox’s VP engineering, to know it, and you’ll hearken to my podcast interview with him for extra. However right here’s a graphic to assist illustrate why strain balancing issues. It’s additionally quite a lot of textual content (sorry, not sorry), however that’s as a result of it’s so much to elucidate.
What’s the TL;DR model?
The brand new GRIP dampers allow you to use extra compression damping whereas nonetheless being much less harsh due to new compression damping valves that allow the fork react extra rapidly to high-speed impacts. For those who’d prefer to how they did it, learn on…
Each fashionable sealed monotube damper cartridge makes damping at two locations – the compression Base Valve, and the Mid Valve. The Base Valve is the place the compression damping circuits (shims, ports, valves, and so on.) are situated and has usually been the one place the place compression damping was managed (for all manufacturers, not simply Fox).
Whereas it could appear to be the Mid Valve is a plunger that pushes oil up by way of the Base Valve, the truth is that it’s successfully a sieve that lets oil cross by way of it freely between areas B and C within the graphic above. Because the Piston Shaft is pushed into the damper, it displaces oil, and that oil has to go someplace…and that someplace is thru the Base Valve into space A.
That oil in A then compresses the IFP, which has a coil spring behind it to push the oil again by way of the Base Valve throughout rebound (extra on the IFP later).
So, as a result of oil principally* flowed freely by way of the Mid Valve, the oil strain in B and C was principally the identical. That meant the entire compression damping needed to be dealt with by the Base Valve’s Excessive (HSC) and Low (LSC) valves.
The issue is, that takes an excessive amount of time & drive.
We’re speaking milliseconds right here. Fox says a typical full compression once you hit an enormous bump takes about 30 milliseconds. Reside Valve growth taught them that people can detect one thing as rapidly as 5ms (Not related right here, however as an FYI, Reside Valve can detect and open the valve in 3ms).
So, because it solely takes us about 5ms to note a bump, and about 30ms for an entire HS compression, making the compression circuit react even a number of milliseconds sooner is the distinction between a bump feeling harsh versus managed.
The important thing to studying this was creating new strain sensors that had been quick sufficient to seize what was occurring inside these new dampers. Fox is now measuring right down to sub 1ms, and primarily based on the brand new knowledge, they made a number of key modifications:
- They added a compression damping circuit to the Mid Valve
- They made the Base Valve’s diameter a lot bigger
- They gave the HSC shim stack dramatically extra tunability
Let’s break these down:
Mid-Valve compression tuning
The principle challenge was that as a result of the GRIP 2’s Base Valve was doing all of the work, that damper’s HSC circuit needed to be sturdy sufficient to withstand minor impacts. That meant it took a number of milliseconds longer for sufficient strain to construct to activate the HSC, which meant it took a number of milliseconds longer for it to start out controlling an affect.
From a rider’s perspective, these milliseconds are perceived as “harshness”.
So, Fox added some mild compression damping to the Mid Valve, which may react extra rapidly. As a result of the system is now reacting extra rapidly to manage an affect, the general damping may be softer initially, so the fork feels much less harsh.
By frivolously proscribing the movement of oil from space B to space C, they’re altering the strain differential between the 2, therefore the time period “strain balancing”. It’s not an enormous change, as a result of something dramatic would begin to create a vacuum in C, which would scale back or eradicate the rebound circuit’s means to perform. So, it’s balanced, to create the specified impact with out messing up rebound.
Then, because the affect compression forces develop, they begin driving the Base Valve’s circuits, however these at the moment are higher, too:
Larger Base Valve = higher movement
Notice the distinction in base valve diameter within the picture above (GRIP 2 on the left, GRIP X2 on the precise). Through the use of the Mid Valve to deal with a few of the damping, Fox may use a bigger diameter Base Valve with greater ports and extra shim stacks. This additional movement gave them extra management over the transition from oil flowing by way of the orifices (low pace) to pushing open the shims (excessive pace).
Smoothing the discontinuity in forces between these two is how they keep clean traction throughout that transition in order that there’s no sudden distinction in how the fork behaves because it transitions between gradual and quick compressions.
For the brand new GRIP X2, that additional house additionally allow them to use extra and bigger diameter shims within the high-speed circuit’s shim stack. The picture above exhibits the minimal shim stack of the GRIP 2 versus the bigger X2, and I’ll clarify why that issues additional down when discussing the X2 damper particularly.
No extra FIT4 damper
All three now use their spring-backed IFP, there’s no extra FIT4 damper within the lineup. We dive into why within the podcast, examine that out, however the wanting it’s this: Eliminating the FIT4’s bladder, which wanted room to broaden to carry oil overflow because the fork compressed, meant much more room for the damper itself…which is an enormous a part of how they gained the additional diameter to do all that stuff talked about above.
The spring-backed IFP design can also be easier and extra dependable. It has a bleed port (the little gap on the facet of the tube within the picture above) that lets any damping oil that will get ingested into the IFP to bleed out and flow into into the lowers slightly than get trapped and trigger the fork to “pump up”. The damping oil is similar as what’s contained in the decrease legs, so it’s superb in the event that they combine.
All of this equals extra management, much less harshness
Since each the Mid Valve and the high-speed circuit can react extra rapidly, slowing down the fork as quickly because it begins to compress, you may add extra high-speed compression damping, and but have a much less harsh fork. Principally, you don’t need to run the HSC vast open to have a “plush” fork anymore. Or, as they put it: “Help once you want it. Damp extra, harsh much less.”
There’s additionally nearly no lag within the transition from the low pace to the excessive pace, which a few of their high riders had been delicate to. The forks really feel extra constant and predictable all through their journey no matter whether or not you’re swooping by way of a berm, ripping throughout roots, or each concurrently.
*NOTE: Technically, Fox’s prior GRIP 2 Mid Valves did play a small position within the fork’s tune; they weren’t utterly benign. However for sensible functions, the brand new GRIP dampers made them an lively a part of the fork’s compression damping. Oh, and that new sub-1ms testing tools? Brown says they’re seeing extra issues at that degree that they assume they’ll enhance sooner or later…
2025 Fox GRIP damper choices
The brand new GRIP dampers are category-optimized primarily based on the use case:
- GRIP SL (xc / marathon / downcountry)
- GRIP X (path / all-mountain)
- GRIP X2 (aggressive path / enduro / gravity)
For SL, the main focus was weight. For X, the main focus was giving the everyday mountain biker a candy spot of efficiency and helpful adjustability with out bells and whistles they hardly ever use. For X2, it was about maximizing tunability, each internally and externally, for riders pushing the boundaries.
Management dials are goal constructed for every damper, too, supplying you with entry to solely the options you actually need for a given use case.
The brand new dampers are principally lighter than earlier than, too:
- GRIP SL is 60 grams lighter than FIT4 in 100mm journey.
- GRIP X is 120 grams lighter than GRIP X2 in 160mm journey
- GRIP X2 is simply a 20 gram improve over GRIP 2 in 160mm journey
Right here’s what you’ll want to find out about every damper:
GRIP X2
Coming from the GRIP 2, which was good, their purpose was to extend tunability. Having spent years customized tuning the forks for his or her high professional riders, they wished to make it simpler to do inner customized tuning for the professionals, but additionally add extra helpful exterior tuning so each rider can profit from it. Mixed with the brand new Mid Valve structure, it delivers “tunability with out penalty.”
Principally, they wished to provide the bike a trophy truck really feel, the place the purpose is to maintain the tires on the bottom whereas minimizing vibration and damaging suggestions from reaching the rider. However you want some suggestions for a motorcycle, so the rider can sense what the bike is doing and assist keep traction.
The compression base valve is way bigger (24mm vs 20mm), and there are extra shims. GRIP 2 had 7 shims, the GRIP X2 has 23 shims. That’s greater than a 3x enchancment in tuning vary.
Additionally has a sooner response, so it’s appearing on the compression extra instantly for a extra predictable really feel, they usually say it makes the highest finish of the damping curve extra helpful. That means, for those who get into a very aggressive path, you may crank the high-speed compression damping as much as deal with it, which isn’t one thing we’d usually do with the previous system.
The massive purposeful distinction is that the HSC ports at the moment are bigger, permitting extra oil movement, in order that they added extra shims to withstand that movement. Principally, they moved the HSC oil movement administration from the ports to the shims, which supplies them much more tunability. The wave spring (to the precise of the shim stack within the picture above) hundreds an intermediate “pivot shim”, which places extra strain on the middle of the shims. The (black) hat that preloads the pivot shim is a tunable merchandise…which means, it’s a component that they’ll swap out with completely different designs to customized tune the fork internally.
Lastly, there’s now higher separation between compression and rebound so there’s much less cross discuss between them. One gained’t have an effect on the opposite.
The GRIP X2 retains the four-way adjustment of exterior excessive/low pace compression and excessive/low pace rebound. It’s obtainable on 36, 38, and 40 sequence Manufacturing facility and Efficiency Elite forks. Some bikes could spec this damper in a 34 chassis, however it’s an OEM-only choice.
GRIP X
Fox’s purpose for the GRIP X damper was to “Dominate All-Mountain” by providing 4-way adjustable efficiency in a 3-way damper. That means, it’s going to carry out like an X2 for many riders, however loses the exterior high-speed rebound adjustment.
Previous to this, you wanted to decide on between an endurance, XC-focused damper (FIT4) or a gravity-oriented damper (GRIP 2). Now, the GRIP X is purpose-built for what most of us are driving – path to all-mountain.
It makes use of a equally outsized base valve because the GRIP X2, however has its personal tips tailored for riders who climb up trails as a lot as they bomb down them.
The largest distinctive characteristic is a brand new “Tremendous Agency” mode mixed with a brand new outer HSC bezel with a small indicator nub.
The middle LSC dial acts similar to it did earlier than, supplying you with an enormous vary of low-speed compression adjustment. However the brand new HSC knob sweeps 170º and serves a number of functions. The primary ~90º is simply pushing a spring down on the shim stack, firming up HSC. After that, it begins to press down on the low-speed compression valve, finally closing it off utterly.
This allows you to use a single dial to agency up the fork for climbing, then rapidly open it again up, all with out affecting the low-speed compression circuit. That means, you may depart LSC the place you prefer it, however nonetheless have one thing like a “climbing” mode. The addition of the tiny nub lever offers a visible indication of the place it’s at, so you may rapidly return to your most well-liked HSC setting, too, with out having to rely clicks.
For Rebound, they restricted it to LSR, which allowed them to make a smaller, easier mid-valve (examine the comparability photograph up above, it’s so much smaller than GRIP X2!). Additionally they narrowed the adjustment vary a bit, so every click on could have a extra nuanced adjustment.
You’ll discover this on the Fox 36, 38, and 40 forks in Manufacturing facility and Efficiency Elite trim ranges.
GRIP SL
For the SL, the purpose was to make the lightest potential damper whereas additionally enhancing efficiency relative to FIT4. Racers need mild weight, the power to hold extra pace with extra confidence, and a lockout. The GRIP SL damper offers all three.
A 3-position compression knob has the everyday Agency, Medium, and Open modes, however it’s additionally obtainable with a distant lockout choice. The lever offers solely low-speed compression damping controls, and the lockout has a blowoff simply in case.
The GRIP SL damper is made for journey from 40-130mm journey, for gravel to 34 SC, and all else being equal, this plus a brand new Kabolt SL axle (it’s butted on the within to save lots of 12g) makes the 2025 34 Step Forged fork 62g lighter than earlier than.
The Open makes use of a mixture of mid-valve and base-valve (strain balancing!) for a buttery clean really feel over any terrain. The Medium (“pedal”) place provides extra damping into the bottom valve to provide it a little bit of a platform. And the now-larger lever on the knob makes it simpler than ever to succeed in down and flick it into the “attack-ready” Agency mode, whether or not the fork is loaded or now. It has a 140º sweep from open to closed, with stable detents so that you don’t need to guess the place it’s at.
Obtainable on 32 TC (gravel), 32 SC, and 34 SC forks in Manufacturing facility and Efficiency Elite ranges.
New GRIP dampers are backward suitable
All of those dampers are backwards suitable with all present chassis, supplying you with the power so as to add these to all of their present forks way back to 2021-22, relying on mannequin.
The MY25 forks will even have new bushings, which not have bleeder channels to flow into oil above and beneath the bushings. Now, these ports are forged into the lowers, so you may’t retrofit the brand new bushings into your older fork, however it actually doesn’t matter – The brand new seals do technically have decrease contact strain since there’s extra floor space, which suggests much less friction, however even Fox says the distinction is minimal. Marginal positive factors, although…
Additionally they have an eMTB tune, usually with a barely softer compression tune that’s higher for an eMTB’s usually sooner climbing speeds.
What concerning the Efficiency-level forks?
The prior GRIP 2 damper carries over on the Efficiency degree merchandise, however with up to date tune and strain balancing to attain a few of the similar efficiency enhancements. It gained’t be Manufacturing facility degree, however it’s higher than earlier than.
Do the fork chassis change? Are they journey adjustable?
The uppers and lowers for all forks besides the 32 SC carry over unchanged. The 32 will get an entire overhaul, which is roofed in a separate put up. For the remainder, Fox additionally affords e-bike particular chassis.
Journey choices for all chassis are:
- 34 SC – 100-120mm
- 34 – 120-140mm
- 36 – 140-170mm
- 38 – 160-180mm
- 40 – 203mm
Every journey increment requires a definite air spring, as a result of the piston must line up with the switch port. So, sure, the forks are journey adjustable, however you need to purchase a brand new air spring to vary them.
Whoa, whoa, whoa… what’s up with that Gold fork?
That’s a particular version popping out this summer time to have fun Fox’s fiftieth anniversary. Extra particulars will come nearer to its launch date, however in order for you one, discuss to your native bike store now in order that they’re on it.
First impressions journey evaluation, coming quickly.
