Fox’s Podium Factory inverted fork is a disruptor in the mainstream enduro suspension market, offering something entirely different compared to the competition.
To gauge whether this novel design is worth it, I pitted the Podium Factory against the current market leader – RockShox’s ZEB Ultimate Charger 3.1.
The ZEB single-crown fork has undergone several iterations – some good, some bad – since its launch in 2020, but this version with RockShox’s most recent damper is the crème de la crème.
I tested the two forks back-to-back on the same trails on the same days on two near-identical bikes to get a feel for how they rode, and where, or if, any performance benefits could be felt.
How I tested the forks
In order to make the test as fair and accurate as possible, I used two almost-identical Marin Alpine Trail XR test bikes.
I went to great lengths to ensure the most important components were identical. The frame, shock, shock setup, wheels, tyres, bar, stem, grips, crank length and pedals were the same across both bikes.
There were some differences between the two, including the brakes, drivetrain, seatpost and saddle, but none of these things had any significant impact on fork performance.
The two bikes were set up identically, too.
That includes rear-shock sag and fork sag, measured using scales on both the front and rear wheels on both bikes to ensure the same body-weight balance, and therefore sag.
Tyre pressures were the same, as was bar roll.
The Podium bike weighed 18.92kg, while the ZEB bike weighed 18.23kg. This difference is slightly bigger than the 410g difference between the two forks.
To help bridge the gap between the bikes, I added 280g (the difference between the ZEB and Podium’s weights and the bikes' overall weights) to the frame storage on the ZEB bike.
While not scientifically ideal, it was intended to help isolate any performance advantages between the lighter ZEB and heavier Podium to the difference in fork weight alone.
- Frame: Marin Alpine Trail XR
- Shock: RockShox Super Deluxe Ultimate with 400lb spring, set to 25 per cent sag, all damper adjustments fully open
- Wheels: DT Swiss FR 1500 29in front and rear
- Tyres: Pirelli Scorpion Race DH T 29x2.5in
- Bar: OneUp Aluminium Handlebar, 35mm rise, cut to 770mm
- Stem: OneUp Stem, 35mm long
- Grips: Fabric Funguy/Cannondale Trailshroom
- Crank length: 165mm
- Pedals: Deity TMAC
Fox Podium Factory
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- £2,199 / $1,999.99 / €2,399 / CA$2,679 / AU$3,349
- 2,730g (170mm travel, 29in wheel, 225mm steerer)
Fox Podium Factory specifications
Fox’s inverted or upside-down (USD) Podium Factory fork is claimed to offer improved fore-and-aft stiffness, thanks to its striking non-conventional design.
The chunky 47mm upper legs – which are where a traditional fork’s stanchions would be – lay the groundwork for that increase in stiffness.
According to Fox, the Podium’s rigidity is close to the dual-crown 40’s, something other single-crown forks can’t boast.
The aim of increasing stiffness in this plane was to boost fork predictability; a fork that flexes back and forth, according to Fox, is hard to tune.
Adding to the aluminium uppers’ strength is the AI-designed crown, which is meant to add strength without excessively increasing weight.
The 36mm stanchions slide into the oversized uppers.
Stiffness is important
It runs a 20x110mm front axle, found on downhill forks. While it’s not a new standard altogether, single-crown forks usually have 15x110mm spacing.
Fox blind tested multiple axles – an element crucial for tuning torsional stiffness – and settled on the 20mm steel axle fitted.
According to the brand, the Podium has torsional stiffness equivalent to a 160mm-travel Fox 36.
Bushings equal performance
Along with improved chassis stiffness, the USD design means Fox has increased bushing overlap.
This is the measurement between the top and bottom of the upper and lower bushes, and the bigger it is, the less friction there will be and the smoother the fork will feel.
Traditional forks are limited in how much bushing overlap they have before the lowers, and therefore axle-to-crown measurement, need to grow.
Better managing the forces during compression – thanks to the bigger and wider bushes – means fork-compression behaviour is more predictable and reliant on the damper rather than influenced by unwanted friction.
Unlike a conventional fork, as the USD model compresses, the distance between the axle and bushes decreases, helping to better manage peak forces, potentially helping them feel smoother.
On a regular fork, this distance remains the same because the bushes and axle are fixed in relation to one another.
Dampers and springs
The GRIPX2 damper’s had a re-tune to compensate for the free-moving nature of the Podium.
Fox has increased compression damping by swapping out the three-port mid valve for a two-port version. According to Fox, the rebound has also been adjusted to accommodate for a lower unsprung mass.
But custom tunes, such as RockShox’s latest forks, aren’t officially available from Fox.
The air spring now features Fox’s GlideCore design, which uses nitrile butadiene rings to enable the spring to cant inside the stanchions. This helps isolate the fork’s bending or twisting from causing binding inside the air spring, resulting in more smoothness.
Fox Podium Factory performance
Off the top, the Podium is exceptionally supple, absorbing the minutiae of bumps on the trail, whether that’s cruising up a fireroad or hammering down your favourite runs.
This silkiness on innocuous bumps translates to exceptional comfort and grip on the roughest, wildest terrain; the fork’s eager to use its travel to keep you from getting fatigued or pinged off-line.
But that smoothness doesn’t come at the detriment of mid-stroke support or bottom-out resistance.
In high-load G-outs or deep-pocketed berms, it remains steadfast and composed even when you’re hammering it aggressively to load the front wheel for extra speed, grip and control.
There are no signs of twisting, steering vagueness or a wandering front wheel.
Precision and accuracy don't come at the expense of this plush, smooth feel, despite USD forks having a reputation for being ‘flexy’.
On-the-brakes, steep, rough and fast entrances to turns are where it really shines, though.
Here, you’re loading up the damper, spring and chassis with the most extreme forces possible – your full body weight and momentum is being held by the fork as you brake; essentially, the fork is trying to twist, buckle and bend as you decelerate.
But the Podium remains unfazed, responding actively, calmly and with plenty of plushness on every bump, even as you load them up, ready to expel your energy into the turn.
Strike a line across a camber infested with roots and rocks and the performance is impressive.
Instead of the tyre scraping and sliding across the diagonal bump faces, it tracks calmly and smoothly, barely breaking traction.
The Podium’s not the silver bullet for all your riding misdemeanours, but it certainly lends a generous helping hand and will benefit expert racers and less experienced riders alike.
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RockShox ZEB Ultimate Charger 3.1 fork
- £1119 / $1,159 / €1,249
- 2,320g (170mm travel, 29in wheel, 225mm steerer)
RockShox ZEB Ultimate Charger 3.1 specifications
While the ZEB’s chassis has remained unchanged since its 2020 introduction, the internals have had plenty of updates since the Charger 2.1 damper it launched with.
This latest Charger 3.1 model is arguably the fork’s best iteration, combining the plushness and smoothness of the older 2.1 with the support and control of the 3, launched in 2022.
Internally, the damper’s got a re-tuned low-speed compression circuit designed to improve sensitivity and traction. Oil flow is increased by 68 per cent, according to RockShox.
The internal floating piston (IFP) inside the damper has also been reworked and is claimed to improve consistency during compression and rebound.
Also tweaked is the mid-valve check spring, helping to further combat the choked feeling the Charger 3 could sometimes have.
Despite the reduction in damper forces, with the high-speed compression adjuster fully closed, the high-speed circuit has more damping than the Charger 3.
This increased range of adjustment should make the Charger 3.1 more adjustable and suitable for different riding styles.
So tuneable
Along with these stock adjustments, RockShox is offering different compression and rebound tunes for the Charger 3.1.
With two different compression tunes (standard and heavy) and three different rebound tunes (light, medium/standard and heavy) – that are readily available to buy, and fitment instructions easy to find online – the ZEB is more adaptable than ever.
Not just the damper
Tweaking the damper wasn’t enough for RockShox.
By improving the fork’s bushings, the brand claims it has managed to reduce friction substantially.
Those improvements are not focused solely on ironing out tolerance issues and making sure stricter quality-control measures are in place, they’ve also been increased in size.
That meant a small internal rolling change to the ZEB chassis; you can’t retrofit the new bushings to a Charger 2.1 or Charger 3 ZEB.
Continuation of tech
Carrying over from the previous-generation ZEB are ButterCups and the DebonAir+ air spring.
ButterCups are small, rubberised bumpers or pucks sitting between the fork lowers and the bottom of the damper and spring assemblies.
The pucks are designed to absorb high-frequency, low-amplitude vibrations, essentially smoothing out bumps neither the damper nor air spring can.
RockShox claims the pucks reduce this type of vibration by up to 20 per cent compared to a fork without them.
The DebonAir+ air spring has been designed with a larger negative spring volume in a bid to further improve sensitivity.
The air-transfer port is ‘lower’ into the fork’s travel, so when the two chambers equalise, there’s more pressure in the negative spring than before.
RockShox ZEB Ultimate Charger 3.1 performance
The changes RockShox has made to the Charger 3.1 damped ZEB are nothing but positive.
It’s smoother and more fluttery, while retaining the much-loved support and composure of the generation it supersedes.
Tracking the ground impressively, the ZEB’s capable of preventing the smallest bumps from entering your range of perception, glossing over the trail’s surface.
Increase the impact’s size and frequency, and it still delivers; there’s no choking, harshness or compression spike.
Up the ante with flat-out, aggressive riding where you’re pushing, pumping and squashing the bike into rough terrain and the ZEB still handles everything with a forgiving predictability.
While it’s eager to use its travel, it doesn’t bottom out readily or wallow around in its mid-stroke.
But the ZEB sits deeper in its travel than other forks, so much so that its dynamic sag on mellower trails may encourage you to raise your bar.
My advice is don’t. Instead, add a bit more low-speed compression damping to lift or maintain the ride height, because once the going gets rough, that impressive damping takes over and stabilises the front end.
On this type of gnarly trail, the chassis’ performance is surprise-free. It’s stiff and controlled without feeling harsh or rough – the 2020 ZEB still proves it’s one of the best.
Being picky, there are fleeting moments when harshness can creep in.
To experience it, you’ll need to be loading the fork up in every direction. Hard on the brakes, down a steep, rough, braking-bump littered section into a turn, as the damper, chassis and spring all work overtime to support your weight, some roughness creeps in.
It’s far from off-putting, but is certainly noticeable in this rather specific scenario.
How do the Fox Podium Factory and RockShox ZEB Ultimate compare?
Installing a wheel on the Podium is harder than the ZEB.
The dropout is attached to the stanchions, which can rotate freely in the uppers, and compress and extend independently. Therefore, slotting the wheel between the dropouts and sliding the axle through takes a bit more patience.
I found the easiest way to do it was with the bike upside-down.
Next are the pinch bolts and axle.
These must be torqued to the correct settings, otherwise the fork – according to Fox – loses some of its ‘magic’. While the ZEB’s axle also requires a torque wrench, there’s only one bolt to do up, rather than five.
Fork setup is easy and intuitive on both models, and even the location of the damper’s adjusters on the right-hand fork leg (at the top or bottom of the fork) is the same.
The ZEB’s air spring is inflated at the top of the left-hand leg and the Podium’s is at the bottom. Care needs to be taken when opening the cap or installing and removing the shock pump to not lose any oil.
To stop this from happening, it’s best to make air-spring pressure changes with the fork upside-down, so the top cap is pointing upwards. Opening the air-spring cap – using a cassette tool, like RockShox’s forks – must also be done upside-down.
On the trails
First things first; both these forks are exceptionally plush-feeling and incredible on the trails.
Each one is a glowing example of the epitome of enduro bike single-crown suspension performance – whichever you choose, you can’t go wrong.
But there are noticeable differences between the two.
Alpine wonders
Imagine an Alpine singletrack darting through widely spaced pine trees, carving across the steep gradient of a towering mountain.
It’s littered with rocks and roots, and while some of it is benched out – thanks to riders forming small catches at natural pressure points in pauses between the messy root beds – most of it is a roll of the dice balancing act between grip and slip.
You’re powering across the cambered ledge with your ZEB; it’s working marvellously to absorb as much of the chatter as it can, but occasionally the front wheel deflects on the diagonal leading edge of a bump, rock or shiny root.
Your tyre scrapes along a rock’s edge, causing the bike to fire off-line.
You tense up and react with an opposite throw of your weight to mitigate how far off your intended trajectory you go, doing your best to maintain forward momentum. You heart’s racing and adrenaline flowing.
This brief moment of terror keeps you on your toes and ups the intensity of the ride; while some might thrive on the unpredictability, others are likely to question their bike’s setup or their own skills.
In my experience, this type of scenario is shared universally with most enduro-style traditionally designed forks. The chassis’ torsional stiffness is intentionally high, and fore-aft, it’s relatively flexy. Combined, these two characteristics can lead to the slip and grip described above.
It’s thrilling and exciting, but far from ideal if you’re looking for the calmest, most predictable ride.
Fox’s Podium reduces this noticeably.
Re-run the scenario through your head, but this time you’re riding the torsionally flexier but fore-aft stiffer Podium.
As you brace yourself for a second go at the rodeo on the technical section, the fork filters out most of the unwanted slip and grip, resulting in a calmer, muted and more certain ride.
The tyre no longer slides along the edges of rocks and roots. Instead, it feels as if it’s tracking the trail’s lumps and bumps with impressively forgiving precision.
Instead of waiting for the natural catch berm to pressure the bike to grip before going light again, you can maintain an even pressure across the whole camber, safer in the knowledge there’s more traction on tap.
I’ll admit the difference is maybe less pronounced than my explanation depicts, but it’s certainly there; the Podium’s just got a more neutral and less hectic feel to it.
It’s likely this is a combination of the chassis flex and stiffness in the right places, along with the improved smoothness, the extra bushing overlap and size.
Loading them up
This time, imagine you’re riding a steep, fast, rough track with plenty of bombed-out, on-the-brakes sections that lead into deep-pocket berms.
Speed management is key to riding well here, as is resisting the multiple impacts when you’re slowing down.
Again, imagine you’re riding your ZEB bike.
The section’s super-rough and you’re braking hard – the fork’s being bent backwards by the combined braking forces, and your body and bike wanting to maintain its current trajectory.
The damper’s working hard to reduce dive and maintain support.
This doubles down with each bump; their sharp crests contact the front of the wheel, again flexing the fork backwards.
Working harder still, the damper’s now got high-speed hits to deal with at the same time, as it tries to insulate your hands from each bump and provide grip.
The fork’s maxed out.
But now you need to start turning, too. The chassis is not only getting bent back and forth, it’s also having to deal with twisting loads of aggressive cornering.
Inevitably, something must give.
In the case of the ZEB, that’s the smallest amount of harshness or unwanted feedback through your hands.
Unsurprisingly, when you’re pushing the fork to its limits like this, a minor amount of buzz from each of the bump’s crests gets through the fork’s damper and into your range of perception.
Remove one of the input factors by laying off the brakes or straightening up the bike and the harshness vanishes.
Now switch to the Podium bike on the same trail and section, and enter it with just as much aggression and ferocity as before and brace for impact.
Instead of there being a hint of harshness, the feel through the front wheel is creamy and smooth, muted, hushed and controlled.
While the difference isn’t astronomical, it’s certainly perceptible.
The Podium remains plush and smooth when you’re twisting, bending and torturing it in the wildest sections.
This equates to more grip, control and comfort than its competition, resulting in a faster, smoother and more fun ride.
Again, there’s clearly something in the USD layout and other internal design changes.
But isn’t the Podium too flexy?
No is the short answer.
During the test period, there have been multiple instances of overloading the front end of the bike in the deepest, sharpest and fastest berms on some of the recently reworked trails in the Tweed Valley.
Neither the Fox nor the RockShox exhibited any unwanted flex, steering vagueness or otherwise in these scenarios.
Even larger or more aggressive riders – in my experience – need not worry about either being too flexy.
Fox Podium Factory vs RockShox ZEB Ultimate bottom line
Which is best boils down to the performance difference between these two forks – and does that warrant the extra £1,080 / $840.99 / €1,150 you have to pay for the Podium?
Frankly, the Podium’s performance isn’t twice as good as the ZEB’s – like its asking price – but it is qualitatively better on every terrain and trail I tested it on.
It’s smoother, more controlled, plusher and easier-going on your hands. This translates to a bike that feels better to ride, has more grip and offers more control.
But the difference isn’t massive – it’s unmeasurable in terms of run times – rather, it’s a pursuit of marginal gains.
If money’s no object or you’re the type of rider who wants to eke out every bit of performance from your bike, the Podium wins hands-down. Otherwise, save your cash and go for the ZEB.
