As a fan of 27.5″ wheels, the ability to retrofit a Specialized-produced MX link to the 2021 Specialized Stumpjumper EVO was a deciding factor in my decision to acquire the bike for my personal quiver. Adding the mixed wheel option to the 2021 EVO’s wide range of adjustability is music to the ears of a bike geek like myself.
The EVO features six distinct geometry settings, allowing riders to adapt the bike to their personal preferences and needs. While the latest iteration of the Stumpjumper EVO is only available with 29″ wheels, the aftermarket MulletLink from Specialized allows the use of a 27.5″ rear wheel with a minimal effect on the geometry of the bike.
They even include it in their (very cool) interactive, dynamic geometry chart.
To convert the EVO to run mixed wheels, the MulletLink and a 27.5″ wheel is all that’s required. The rear wheel is the biggest cost involved; in comparison, the 29″ to 27.5″ shock link runs about $60 online. I sourced mine from Fanatik, and it arrived quickly. As I’m running Shimano 12-speed on my build, I was planning to build a custom rear wheel around the new Shimano XT hub, but anxious to get on the bike, ended up sourcing a complete rear wheel that featured an oh-so-sweet Shimano XTR rear hub.
Stumpjumper Evo MulletLink Installation
For experienced mechanics, the install is straightforward. Remove the old link, noting the order of the hardware and spacers, then replace the stock link with the MulletLink.
The MulletLink includes bearings that are already installed, but mounting hardware and the spacers are re-used. The biggest challenge is trying not to drop the spacers on a dirty shop floor while squeezing it into place. (challenge failed)
While the stock link was off the bike, I had the opportunity to compare it to the stock 29″ link. Aside from the longer length, there isn’t a lot of variance between the two.
After installing the MulletLink, I installed the new rear wheel and headed out for a quick ride.
2021 EVO MulletLink First Impressions
When I acquired the Stumpjumper EVO, I elected to follow the sizing recommendations and selected the S4 size, which is the equivalent of a size large. I’ve been embracing the longer reach lengths of modern trail bike geometry, and while the reach is comfortable while climbing and the high-speed stability is nice, the long wheelbase and longer rear center take away from the maneuverability as well as the slow speed fun factor of the bike. Swapping out the 29″ rear wheel with the 27.5″ immediately creates a new more maneuverable and playful disposition to the EVO.
As I’ve been riding the Specialized Status for a few months, I’m already accustomed to riding with mixed wheel sizes. As you’d expect, the first things I compared were the two bikes and the riding experience of each. Although the EVO only has a bit more travel than the 140mm Status, they have very different personalities. The size medium Status is more jibby, playful, and loves back wheel with its short rear stays. However, the heavier frame is noticeable. The EVO, although it feels like a much larger bike, feels lighter.
The first thing I did was take the EVO to the local bike park to rally a few runs down the downhill BMX/ FourCross track. The Status rules here, but the EVO in mullet/MX mode became notably more fun on the dirt jumps. The bigger test was how the bike would ride on a weekend full of all-mountain shuttles in Oakridge, Oregon.
Stumpjumper EVO MX: On the trail (updated April 2022)
The Stumpjumper EVO in MX mode is a hoot to ride. However, the mullet link with the stock shock is flawed if you like to send it and need the suspension to ramp up properly. I’ll circle back to that shortly; first let’s talk handling.
If you’ve ridden Eula Ridge in Oakridge, you probably figured out that Mullets shred this trail. If you haven’t, Eula is known for steep grades and loose turns that keep you on your toes. Large rotors and big rubber maximize the fun here, and the smaller rear wheel was absolutely dialed in these conditions.
Unsurprisingly, over half of our riding crew were also rocking mixed-wheel setups. Needless to say, we were usually the first ones on the trail, and with the biggest smiles. (our homie on his 27.5″ rig was also loving it)
As you’d expect, the smaller rear wheel in these conditions provides the best of two worlds. You get the traction, hook up, and “mob the trail” roll-over effect of the larger 29″ front wheel, and the jib factor of the smaller 27.5″ rear wheel. Plus, with the smaller rear wheel, the rear-tire-ass-buzz on the steep stuff disappears.
Setting the bike up for big moves is a cinch with the smaller rear wheel. Tight turns, steeps, downhill switchbacks, all easier and seemingly effortless with the MX setup. In the steep stuff, I found myself steering with my hips, and using weight shifts to slap the rear wheel into the berms.
Technical ups, stump-jumping, log-overs, and other types of explosive technical moves are all easier to execute with the 27.5″ rear wheel. The MulletLink config results in a 2mm shorter chainstay length, and the bike is easier to get on the rear wheel as well, though the Status easily outshines the EVO when it comes to the play factor. The EVO is meant to be a capable all arounder though, and it is. Having the second link and rear-wheel configuration essentially give you two bikes in one.
The Flaw with the MulletLink
Let’s just get to it. The rear suspension of the Stumpjumper EVO is too linear for progressive riding. Regardless of the rear wheel size and which of stock links run, the rear end doesn’t ramp up enough, which makes the Cascade Components aftermarket link an appealing upgrade.
With the MulletLink, it’s even worse. Unfortunately, the mullet link negatively impacts the leverage curve, making it less progressive. Even with the largest volume spacer available, the bike bottoms out on hard hits at speed. It’s bad enough I’ve been considering going back to the stock link and a 29″ rear wheel.
Alternatively, I’m looking into options for rear shocks that feature a lot more progression. Williams Racing Products, a British company offers a Mullet Yoke that maintains the stock leverage curve. It is a somewhat expensive fix though. (view it on their site here) My brother is running one of their products on the Specialized Enduro set as a mullet and it performs quite well.
29″ Rear Wheel + MulletLink= not ideal
I was hoping I would be able to simply swap out the rear wheels with the MulletLink to take advantage of the slightly shorter stay length for longer technical trail rides. I figured the higher BB, steeper seat tube and head angle would work out just fine for clip-in XC rides.
The rear shock rate didn’t feel quite right when trying this set up though. The rear suspension didn’t feel progressive enough, so I ordered a Fox Volume Spacer Kit and stuck the biggest spacer in.
It did help a little bit. I didn’t care for this setup at all at the bike park though. I’m going to have to try back-to-back 29″ rides with the MulletLink and 29″ link to get a better sense of how I feel about it.
Mullet/ MX isn’t always better
At this point, you’ve probably guessed I’m a fan of mixed wheels for mountain biking. However, it isn’t always the optimal setup. While I love the mixed wheels on flow trails, in bike parks, and other black and double black diamond technical trail scenarios, when it comes to rock gardens and high-speed shred, I prefer the 29″ rear wheel, which is simply faster.
The best example is the rock garden at the Sandy Ridge Trail system. With big burly 29″ tires, this rock garden is a blast. Going back to the 27.5″ rear wheel — even with a 2.5″ Maxxis Aggressor tire— makes it a bit more of a technical challenge, as the 29″ rear wheel carries its momentum much easier. It’s worth noting I’m not running a CushCore at the moment, or a double down casing, which means I’m also running more air pressure — which is not an optimal setup for burly technical trail.
I’d also rather run a full 29″ wheel setup for longer distance trail rides. I’m in the midst of building up a lighter 29″ rear wheel that I’m planning to pair with 2.3″ tires for longer rides. None of this post is really new information though. Let’s face it, this is the classic 29″ vs 27.5″ argument, applied to mixed wheel configuration.
To simply things, 29= more capability, Mullet=more fun geometry, albeit flawed. In comparison to a full 27.5″ setup, keeping the bigger front wheel does in fact maintain some of the 29″ cheater wheel feel. I don’t see myself owning a full 27.5 bike in the future.
Going with the smaller back wheel makes a 29″ feel far more spry, more playful, and easier/fun on dirt jumps. And squaring off turns is a blast in comparison.
Conclusion: if you’re the owner of a 2021 Stumpjumper EVO, I can’t fully recommend investing in the MulletLink and a 27.5″ rear wheel —though it’s like having a second bike, unless I can find a solution for addressing the lack of progression it doesn’t quite work.
I’m researching options and will update this post if I can find a viable solution.
