-27.5-inch rear wheel, 29-inch front
-150mm rear travel, 160 front
-XS through medium frame sizes
-Matched 27.5-inch wheels on XS
-Carbon frame only
-Delivers on the mixed-wheel "best of both worlds" promise
-Extra rear-wheel clearance is helpful on steeps
-Supportive suspension suits the bike's playful feel
-No size-large option
-Not the greatest traction on the climbs
-High entry-level price point
Get access to everything we publish when you sign up for Outside+.
Can anything billed as a hybrid really represent the best of both worlds? Or are there always going to be sacrifices when you’re headed down the path of a mash-up? I pondered this a lot before testing the new dedicated mixed-wheel Juliana Roubion—the first foray into unmatched wheel sizes for both Juliana and its counterpart, Santa Cruz Bicycles (the Bronson). Wouldn’t it make more sense to engineer around the proven benefits of one wheel size, I thought, rather than attempt to develop a frame and suspension kinematics that allows both wheel sizes to excel?
Then again, Goldendoodles are pretty damn cute.
Mixed-wheel bikes certainly aren’t a new movement in mountain biking, and brands have dabbled with them on and off for years, but the trend surged after the UCI relaxed its rules banning these bikes in competition in early 2019. Big-name athletes started racing (and winning) downhill and Enduro World Series races on mixed-wheel bikes, and lately, iterations of those bikes have been trickling down to us commoners in spades.
The idea, if this is your first introduction to the concept, is that a bigger wheel in the front offers stability at speed and superior rollover capability, while a smaller wheel in the back spices things up with a quick-maneuvering and playful rear-end. That treatment makes a lot of sense for the Roubion, which has been a dual 27.5-inch bike throughout its seven years. It’s got 150mm of rear-wheel travel paired with a 160mm fork, so going full 29er would’ve created too much overlap with the Maverick (AKA Hightower in the Santa Cruz line), a 145/150 29er, but remaining committed to small wheels feels a little outdated for the all-mountain and lightweight enduro categories, where the Roubion is positioned. So Santa Cruz and Juliana went all in—notably, on the same bike they went all-in on seven years ago with the then-burgeoning 27.5-inch-wheel trend—and developed the bike around two different wheel sizes from the ground up. The differences between the Roubion and the Bronson are largely aesthetic, although the Roubion has a lighter shock tune and only comes in XS-M frame sizes (the XS still rides on dual 27.5-inch wheels), while the Bronson is available in XS-XL.
This version of the Roubion is pretty clear in its intentions—with that big wheel up front, a beefed-up fork and a headtube angle that’s been slackened nearly a degree since the last Roubion, to 64.5 (in the low geometry setting), it is itching to go downhill even more than its predecessor. And that’s where I really felt like I reaped its benefits. It is such a natural descender, infusing speed, control and confidence into my ride regardless of the type of trail, or trail condition. On one of my favorite local rides, there’s a steep rock garden that looks so chunky and menacing at the top that I almost always roll up to it, decide it looks too sketchy to commit and chicken out. The Roubion is the first bike I felt confident enough on to stay off the brakes and roll in with the speed required to skim down the waterfall, dabbing be damned. And despite the smaller wheel, the rear end followed right along, the tire holding traction and obediently sticking to my line.
On the bottom of that trail, the rock turns to loose dirt that funnels through a series of steep, twisting turns, and this is where the rear end felt markedly different than a full 29er. The quick cornering and snappiness gave the bike a playful feel that can be elusive on a bike with two big wheels. At first, that feeling caught me off-guard—I’m so used to the more sled-like attributes of a 29er that I thought I was going to lose control of the rear end as it whipped around the switchback—but once I adapted and started leaning into that added little bit of unpredictability, the bike became even more fun to ride. And this may seem like a small thing, but it was a real bonus that the smaller rear wheel wasn’t buzzing my shorts on those steep descents.
As much as I liked the Roubion on my home trails in SoCal, my affinity for it leveled-up in Bellingham, Washington, where this bike instantly felt at home in the loam and roots. On one trail known for its natural, ungroomed demeanor, not-crazy-steep, but a fast smorgasbord of roots, small jumps and narrow, fern-lined singletrack, I felt like a significantly better rider than I know myself to be, especially on a trail I’d never before ridden, as I charged through the tech and entered corners blindly without the compulsion to nervously grab handfuls of brakes.
Good trail design? Perhaps. Good bike design? More likely. The balanced feel of the Roubion is surely a benefit of the size-specific chainstays on each frame size—436mm on the size medium I tested—as well as a moderate 452mm reach. Santa Cruz’s signature VPP suspension improves with every refinement, and this time around, it gained a longer shock stroke length to achieve a lower leverage rate, resulting in less pedal feedback. Climbing was helped along by the 76.6-degree seat angle (low geo setting), which positioned my body optimally even on the steeps, although I did need a bit more support while grinding out seated climbs, and toggled the shock in those scenarios. If all I rode were uphill enduros, I’d probably choose a Switch Infinity or DW-link bike for an edge on climbing efficiency, but I’m pretty confident I’ll always prefer descending, and the Roubion’s VPP feels so supportive and active on the way back down that I’ve long forgotten I even climbed when I’m deep in the grins during the descent.
So about my test bike. I got along with it so well that it was one of those testers I really dread having to send back. It was also the ultra-expensive high-end of the Roubion offering, with the carbon Reserve wheel upgrade, fancier, lighter carbon frame AXS electronic shifting and top-of-the-line everything else. It is very blingy. But you can still get into a carbon frame for nearly half the price with the entry-level build, or buy just the frame for $3,700. It’d be nice to see Juliana drive the prices into the $3-$4k range on the Roubion with the addition of an aluminum frame, like it offers in the Joplin 29er.
And perhaps that will come as the mixed-wheel configuration proves its place in Juliana’s line-up—it’s already well on its way to showing that the best of both worlds can be a reality.
Photos: Anthony Smith
Starting at $5,050, the Roubion is not aiming at the entry level. Some Santa Cruz models are available in aluminum, but not this one, though it’s possible that could change. For now, this “R” build is where it starts. The frame uses Juliana’s slightly heavier but just as strong and stiff “C” carbon, which offers the same ride quality as the higher-end CC frame. The suspension Juliana chose shows a similar focus on investing in ride quality, with Fox’s new Float X shock and the stiff-chassis, quality damper of the RockShox Lyric fork. The bones of this bike aren’t missing a whole lot that the bike we tested offers. The brakes and drivetrain fall a little short, though. The slightly narrower-range 11-50 NX cassette uses a more traditional hub design, and would be difficult to upgrade to the wide-range 10-52 SRAM cassette that has set the current standard. And the SRAM G2 R brakes are a little under-gunned for this bike’s downhill capability. If your ups and your downs are steep, an extra $900 for the “S” build gets you a wider range cassette and more powerful Code brakes, as well as a Fox 36 fork and DT Swiss rims and hubs.