Atomik Chubby 43 wheelset review

Carbon, trick hubs, and 27.5+ to smooth out every trail

BikeRadar score4/5

Atomik's Chubby 43 wheels are built for 27.5+ tires. To maximize the plus size ride, Atomik has managed to sneak in a few unique technologies into the rims, some you can see, and some you can't. The wheelset I had in on test was built up by Hubsessed in Utah with Onyx hubs.

Underneath the dust and dirt lays a 12k carbon weave said to add a bit of strength
Underneath the dust and dirt lays a 12k carbon weave said to add a bit of strength
 

Atomik Chubby 43 rim specs

  • 27.5+ rims
  • 12k carbon
  • Hookless bead
  • 43mm external width
  • 36mm internal width
  • 3.5mm bead width
  • Depth: 15mm deep
  • Actual weight: 920g / 1,190g
  • Claimed rim weight: 470g +/- 15g 
  • Finish: UD matte carbon
  • Rim price: $535 / UK and Australian TBC
  • Tested with Onyx hubs

Atomik Chubby 43 technology

The hidden tech in the Chubby 43 rims is the Foam Core Technology. According to Atomik it's "an aerospace foam core wrapped in a layer of composite material that is molded into the structure, creating a pseudo-semi wall rim that boasts increased impact strength, energy dissipation and stiffness while adding additional damping characteristics."

The rims are taped for tubeless compatibility
The rims are taped for tubeless compatibility

The less hidden benefits are the width and height. Reasons to roll wider rims are vast: increased traction and cornering through a better tire profile, allowing lower tire pressures, looking cool, etc. However, the tradeoffs can include more weight, increased rim strikes, and poor handling with too narrow tires. 

To mitigate the weight and rim strike issues, the Chubbys are super thin, only 15mm deep. They almost appear flat which had me a little concerned about cracking. My concerns were completely unwarranted, however. 

The low profile also has kept them looking new. Typically my rims show endless battle scars, the decals get chewed up, knicks are everywhere, and scratches abound. For a bit more protection, the rim exterior is skinned with a custom blended impact-resistant layer of 12k weave carbon.

Atomik Chubby 43 in the dirt

The Atomik rims laced to Onyx hubs proved to be a brilliant match. One of the claims Atomik makes regarding its Foam Core tech is increased damping. The combo of the foam core, the big plus size rubber and the totally silent hub seemed to annihilate all the buzz, vibrations and drama out on trail. 

So how do the hubs play into this? The Onyx hubs are completely, beautifully, wonderfully silent. The magic inside is a one-way Sprag clutch bearing. There's zero ticking, clicking, or buzzing that's the standard song of high-end hubs. The only sounds while riding are the wind and the tires humming over the dirt and scratching around for traction. 

While a little dirty the freehub is decidedly bite free and the cassette came off smoothly
While a little dirty the freehub is decidedly bite free and the cassette came off smoothly

The sheer quiet of the wheels and tires actually made me want to try to be a smoother rider. Less twitchy movements, more like water flowing softly and delicately, yet purposefully down the trail. I know that seems a bit over the top, but when two parts (the noise and the vibrations) are removed from the violence that blasting trail sometimes feels and sounds like, it's a one-of-a-kind experience.

Even though I was trying to be more zen-like in my riding, I still never shied away from sending it full force into the ugly, rocky stuff. Despite my best (worst?) efforts the Atomik Chubby 43s never even flinched; throughout the test period I never once put them in the truing stand. 

In fact, they were so stiff they actually pulled my bike's adjustable rear dropouts out of line more than once. 

Atomik Chubby 43 issues

For whatever reason, I struggled mightily getting tubeless tires to seat on these rims. It wasn't for lack of trying; I used three different pumps, two different compressors, and all the tricks my local bike shop wrench, a tire company engineer, and I could think of. My set came pre-taped, but Atomik has found that Gorilla Tape works better.

1,190g for the rear wheel with rim tape, valve and some miscelanous sealant and dirt
1,190g for the rear wheel with rim tape, valve and some miscelanous sealant and dirt

The other nit pick is the weight. Granted, I'm spoiled with light, super fast carbon hoops on a daily basis, but the heft was noticeable in hand as well as on the bike. Accelerations and changing directions were a bit slower, too. Most of the excess weight came from the 500g Onyx rear hub. Atomik does offer builds with lighter hubs from DT Swiss, Industry Nine and Profile. This also had to do with the heavier 27.5+ tires and their larger footprint. 

Bottom line: Atomik Chubby 43

The bottom line for the Atomik Cubby 43 wheelset with Onyx hubs is they're seriously capably tough. They felt as though they could take on lift-served thrashings and be fine. 

The other thing of note is how they completely changed the bikes they were on. I rode them on both a 160mm travel full-suspension bike and a trail-oriented hardtail and both bikes were transformed. They felt like different machines and made me re-think how I should be riding certain sections of trail. 

Lastly, the ride was intriguing. The calmness and careless ease at which they propelled me down the trail was super interesting to me.  

27.5 tires work only if only super wide, 27.5+ tires in the 2.8in and wider range work best
27.5 tires work only if only super wide, 27.5+ tires in the 2.8in and wider range work best

Russell Eich

Tech Writer, US
Russell fell head over heels in love with bikes in the '90s, and has been involved in the bike industry ever since. Between wrenching in bike shops, guiding professionally, and writing about bikes, Russell has honed an appreciation for what works, gained knowledge of what doesn't, and can barely contain his enthusiasm for what comes next. His two-wheeled passion continues in the Rocky Mountains high above Boulder, Colorado.
  • Age: 39
  • Height: 6'3"/190cm
  • Weight: 175lb/79kg
  • Waist: 34in/86cm
  • Chest: 42in / 107cm
  • Discipline: Mountain, road, cyclocross
  • Preferred Terrain: High altitudes, forgotten singletracks, bike parks, roads without cars
  • Current Bikes: Custom Meriwether steel hardtail, Specialized S-Works Enduro 29, Kona Jake the Snake, Trek 69er, and a bunch more
  • Dream Bike: Yeti SB5c, Intense Tracer 275C, Black Cat custom road
  • Beer of Choice: Gin + Tonic
  • Location: Rollinsville, CO, USA

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