Specialized Stumpjumper Mullet Review | Modifying the Stumpy

Specialized Stumpjumper Mullet Review | Modifying the Stumpy

Wil reviews the 2022 Specialized Stumpjumper in mullet mode

A few months ago we reviewed the 2022 Specialized Stumpjumper. Since then, Specialized sent us out a new suspension link that’s designed to turn the carbon Stumpjumper, which is normally a full 29er, into a mullet bike.

This is an interesting addition because, up until now, only the longer travel Stumpjumper EVO was offered with mullet compatibility. Indeed most of the mullet bikes currently on the market tend to be bigger enduro bikes or heavy e-MTBs, where the smaller rear wheel helps to bring about some much-needed agility.

Given the Stumpjumper is already quite a lightweight and nimble short-travel trail bike, what exactly would the mullet configuration bring to the trail party?

According to Specialized, fitting the mullet link allows you to use a 27.5in rear wheel while retaining the bike’s existing geometry and suspension kinematics.

If you’ve got a new generation Specialized Stumpjumper, it’s now possible to fit an aftermarket link and run it as a mullet with a 27.5in rear wheel.

Turning the Specialized Stumpjumper into a mullet

Just like the EVO, it’s now possible to purchase an aftermarket mullet link for the Specialized Stumpjumper. The link costs $120 AUD and is compatible with model year 2021 and 2022 carbon Stumpjumper frames. It isn’t compatible with the alloy frame or older Stumpys.

According to Specialized, fitting the mullet link allows you to use a 27.5in rear wheel while retaining the bike’s existing geometry and suspension kinematics. This means the head angle, seat angle and BB height should remain the same despite having a smaller wheel out back.

The link already comes with the bearings pressed in, making it an easy switch with the stock link. No special tools are required, just a 6mm hex key.

To complete the test, Specialized sent us out a Roval Traverse Alloy 27.5in rear wheel and a 2.3in wide Purgatory GRID T7 tyre. I also fitted a CushCore Pro insert, in order to mimic the stock 29in setup. The idea here was to keep as many variables to a minimum, so we could get a good feel for the difference in performance.

What changes with the 27.5in rear wheel?

Before hitting the trail I took a couple of measurements in the workshop to see the effect on the BB height between the two link;

  • Stock 29in setup w/flip chip in Low: 325mm
  • Mullet setup w/flip chip in Low: 323mm

So the BB height was slightly lower with the mullet setup, but pretty close.

Also of note, Specialized claims the mullet link increases the rear travel slightly from 130mm to 135mm. Having checked out the leverage rate graphs, the kinematic is very close to the stock link. The mullet link does result in a slight decrease in force towards full bottom-out, which equates to around half a volume spacer’s worth. So when changing to the mullet link, some riders may wish to experiment with fitting a bigger volume spacer to compensate. I haven’t needed to do that myself, and have instead maintained the same shock settings during testing.

2022 specialized stumpjumper mullet
We measured the BB height with the stock setup and with the 27.5in rear wheel.

How does it ride on the trail?

Because the mullet link largely restores the stock geometry of the Specialized Stumpjumper, the riding position is indistinguishable. What I did notice straight away however was a slightly more perky feel to acceleration. The smaller rear wheel and tyre offer a slight weight advantage over the 29in setup, but the mass is also closer to the hub, reducing the wind-up required to get the wheel moving.

As I headed upwards, I also picked up on the lower gearing. Thanks to the smaller circumference of the 27.5in wheel, using the same 10-51T cassette results in a shorter rollout. The effect is a bit like changing to a smaller chainring, allowing me to spin more easily up steeper climbs.

2022 specialized stumpjumper mullet
The lower gearing and perkier acceleration were noticeable on the climbs.

Speaking of climbs, the mullet Stumpjumper surprised me with its agility around tight uphill switchbacks. I’d assumed the whole reason for going to a mullet was about hooliganism on the descents, but it turns out the smaller rear wheel offers some advantages on the climbs too. In fact, there were a number of technical, rock-infested hairpins that I typically have a 50/50 strike ratio on with the stock 29in Stumpjumper. I cleaned these every time on the mullet setup.

Once rolling back downhill, I quickly grew to appreciate the extra arse clearance on steep chutes and while jumping. As a 175cm tall rider with short legs, it’s not uncommon for me to end up with tread marks on my shorts when riding a 29er on steep trails. With the 27.5in rear wheel however, there’s more room to move before those rubber-on-bum moments.

The mullet setup really comes into its own on flow trails, where it feels a little easier to pump through rollers. Manuals take less effort to initiate, and there’s more reward for pushing through the backside of doubles. The sharper turn-in also helps you to flip-flop through successive corners, as well as square off tighter turns when you come in too hot. It’s a great match for the Stumpjumper, which is already quite an agile bike. The mullet setup just takes the playfulness up a notch.

2022 specialized stumpjumper mullet 2023 rockshox pike ultimate
Making the most of the extra bum clearance with the smaller 27.5in rear wheel. This is a key reason why many World Cup downhillers are choosing a mullet setup.

What are the downsides?

Is it all good news with the mullet setup on the Specialized Stumpjumper? No it isn’t. Like everything in life, there are compromises.

Compared to the full 29in setup, the angle of attack for the 27.5in rear wheel is greater, which has an effect on its rollover capabilities. On steep and sketchy off-piste climbs there’s less rear wheel grip, and you’ll feel it’s hanging up slightly more on square edges.

There’s also a slight reduction in outright stability on the descents, particularly when you’re off the brakes and charging through blown-out gullies and hectic rock gardens. For speedy trail ripping across rugged terrain, the full 29in setup is no doubt the faster option.

I’d also speculate that taller riders will find less benefits to the mullet setup. There’s certainly less need for extra clearance over the back wheel when you’ve got longer legs in the first place.

And if you’re already on a lightweight bike with short chainstays, there’ll be diminishing returns when downsizing to a 27.5in rear wheel. It’s not that you won’t notice the difference, it’s just that the advantages are more pronounced on a heavy long-travel bike, where the mullet setup improves the turn-in speed.

2022 specialized stumpjumper mullet
On chunkier terrain, the 27.5in wheel doesn’t offer quite the same grip and rollover capabilities as the stock setup.

Do you actually need the aftermarket link?

While the engineers are likely to disagree with me, the aftermarket link isn’t necessary to set up the Specialized Stumpjumper as a mullet.

Of course anyone can bang a 27.5in wheel into the back of their 29er, but the immediate problem for most bikes is that the BB will be far too low to the ground.

In the case of the Stumpjumper, I tried fitting a 27.5in rear wheel with the stock link. With the flip chip in the Low position, the static BB height measured just 315mm off the ground, which is stupid low. On the trail I was clipping pedals all of the time, to the point where it became somewhat dangerous when riding through lumpy rock gardens. This setup I would not recommend.

2022 specialized stumpjumper mullet
As well as testing the mullet-specific link, we also tried the stock link with a 27.5in wheel. The results were mixed.

Flip the geometry chip into the High position however, and the BB lifts to 322mm off the ground. That’s only slightly lower compared to using the mullet link in the Low position.

Turns out that the bike rides fine in that setup, though I did bash the crank arms and the pedals pretty regularly. And since the flip chip is already in the High setting, there’s nowhere for you to go to lift the BB. Well, unless you fit a longer fork. More on that in a bit.

My advice would for anyone who’s interested in the mullet setup on the Stumpjumper? Try a 27.5in rear wheel in there with the stock link and the flip chip in the High position. If you dig it, but you still want access to both the High and Low geometry settings, then the aftermarket link makes total sense.

2022 specialized stumpjumper mullet
With the 27.5in rear wheel the Stumpjumper is even more playful, offering a sharper turn-in.

What else are we testing on the Specialized Stumpjumper?

As well as testing out the mullet link, you’ll have no doubt spotted quite a few changes to our Specialized Stumpjumper test bike over the stock build.

I’ve been enjoying the squishy 3D-printed comfort of the Specialized Power Pro Mirror saddle, and I’ve fitted a new PRO Tharsis dropper post with 160mm of travel. This has given me an extra 10mm of drop compared to the stock X-Fusion Manic post, while having a similar stack height. Because of the Stumpjumper’s 34.9mm seat tube diameter, I fitted a Cane Creek alloy shim to accommodate the 31.6mm Tharsis post.

I continue to be impressed by the impeccable grip and feel of the new Race Face Atlas pedals, which have quickly become my favourite flat pedal.

Up top is a pair of DMR Deathgrips, and I’ve you’ll see that I decided to ignore the questionable aesthetics and try out the Sendhit Nock handguards. They’re certainly a bold addition to the cockpit, though they’ve proven to be surprisingly effective at shielding my knuckles from the heinous thorns and overgrown scrub that has been enveloping our local trails this winter. A good example of function over form.

Also questionable in terms of aesthetics is the STFU chainguide. Comprising of two modules that sit on the chainstay, the STFU system helps to control chain bounce, reducing noise and reducing feedback through the pedals. Those modules might stick out like a sore thumb, but they certainly do the trick, making for a quieter and smoother ride.

2022 specialized stumpjumper mullet stfu chainguide
It’s no beautiful swan, but the STFU chainguide does provide a smoother and quieter ride.

Pumping up to a 150mm fork

The suspension spec has also undergone some changes. While the 2022 Specialized Stumpjumper comes fitted with a 140mm travel fork on all models, the frame is capable of going to 150mm. Being the curious cat I am, I’ve been trying it out with a 2023 RockShox Lyrik Ultimate and a 2023 Fox 36 GRIP2 to see how the Stumpjumper handles the bigger fork.

The 150mm travel kicks the head angle out closer to 64°, and it also lifts the BB height a touch. Given I’d been bashing pedals more frequently in the Low geometry position, this extra height was welcome. The bigger fork also improved the front-end confidence levels of the Stumpjumper, delivering more grip and allowing me to push a few clicks harder on my local descents.

Buying a whole new fork is not a cheap endeavour, especially if you’re looking at a premium performer like the Lyrik or 36. However, it is a whole lot cheaper than buying a different bike, and in my experience, it’s been a terrific complement to the Stumpjumper’s overall capability and versatility.

2022 specialized stumpjumper mullet
The Stumpjumper will comfortably handle a 150mm travel fork. Along with the mullet setup and a piggyback shock, it feels considerably more aggressive.

It’ll fit a piggyback shock too

Along the same lines, I’ve been riding the Specialized Stumpjumper with the new RockShox Super Deluxe Ultimate shock. This shock has an external piggyback reservoir, though it fits into the frame just fine. It does limit clearance slightly, so I can only fit a smaller 600ml bottle.

Compared to the stock Fox Float DPS shock, the Super Deluxe is 204g heavier (464g vs 260g). Weight aside, the Super Deluxe has improved the Stumpjumper’s performance in almost every way.

There’s great small-bump sensitivity, and the low-speed compression dial allows you to tweak the ride height and support, without making the back end feel harsh. I tend to ride with the low-speed compression in the neutral setting, though an extra click makes a difference when it comes to catching the pedals on technical climbs.

There’s also externally adjustable high-speed compression damping, which I have set one click lighter than neutral to ensure the rear wheel gets out of the way when smashing rocks on the way back down.

Perhaps the biggest improvement with the Super Deluxe shock is the Hydraulic Bottom Out (HBO) function. HBO is an optional feature on the new Super Deluxe, and you’ll be able to spot the shocks that have it via the anodised triangular markings at the end of the stanchion.

Inside this end of the shock is a tapered needle that enters the main piston during the last 20% of the travel. This restricts oil flow and increases damping, providing more support to reduce the chance of a harsh bottom out.

It certainly works too. The HBO has all but eliminated any harshness on bigger landings, giving the Stumpjumper’s otherwise linear rear suspension a welcome degree of end-stroke support without having to resort to adding volume spacers. A top upgrade for sure.

2022 specialized stumpjumper mullet rockshox super deluxe ultimate
The Hydraulic Bottom Out feature is a great upgrade for the Stumpjumper, offering more control on bigger hits and harsh landings.

Flow’s Verdict

Testing the Specialized Stumpjumper with the mullet wheel setup has been fascinating. I don’t think the benefits are as pronounced here as they are with heavier and bigger travel bikes, but they are there for those who are looking for a more playful ride quality, particularly on high-speed jump trails.

It’s also been cool to see how the mullet setup, 150mm travel fork and piggyback shock have influenced the overall riding experience on the Stumpjumper. Those changes have helped to squeeze more stability and capability out of the lightweight chassis, giving it an aggressive feel that has helped to bridge the performance gap with the Stumpy EVO. If you’re not in the market for a whole new bike, consider what modifications your existing bike will handle to switch up its character. It’ll likely work out to be a lot cheaper, but that aside, it’s just a really fun process.

As to what’s next for our Stumpjumper test bike? It’ll continue to shift and morph over the next few months as we use it for some further back-to-back testing. Next up is a battle between the latest RockShox Pike and Fox 34, so stay tuned for that one.

2022 specialized stumpjumper mullet
While it won’t be for everyone, a mullet setup is a relatively affordable way to try out something different, without investing in a whole new bike.
2022 specialized stumpjumper mullet
We’re embarking on some head-to-head fork testing with the Stumpjumper. Stay tuned!


https://flowmountainbike.com/tests/specialized-stumpjumper-mullet-review/

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