Since its launch in 2013, Melbourne-based Curve Cycling has developed an impressive and unique stable of adventure-focused titanium and steel bikes. Perhaps you caught Sam Rice or Pat Valade’s review of their GMX+ or watched Abdullah Zeinab scoop first place at the Rhino Run last year? But before they made race-winning adventure bikes, carbon wheels were their bread and butter. 

After spending time with the alloy rims that came on his GMX+, Sam Rice switched over to carbon Dirt Hoops from Curve and has since put considerable mileage on them. Below, he offers an overview of the wheelset along with an in-depth review…

Inception

In the early days of Curve, founders Steve Varga and Jesse Carlsson started importing “open mold” carbon rims from Taiwan. Manufactured at scale and sold directly to bike brands and wheel builders, open mold designs can be a cost-effective way to source wheels, and it’s what many brands still do today. But for Steve and Jesse, open-molds were a means to an end. Some test rims were great and survived some pretty unique testing methods. Others cracked, crumbled, and failed to make the cut. But then, riding rough-as-guts MTB trails on the bare rim is a pretty gnarly stress test for any carbon hoop.

Four years of tinkering, tweaking, drilling, and destroying later, the guys had learned a thing or two about what makes a strong carbon hoop. So they began developing their first, proprietary rim design. A design that distilled everything they’d learned, plus a gamut of new technologies including a brand new bead profile and spoke bed design. Enter the Dirt Hoops.

Dirt Hoops (Wider 40) Quick Hits

• Constructed from a blend of 3K and unidirectional T700, plus carefully placed
• T800 carbon fiber
• Available in both 27.5” and 29” diameters
• Internal rim width: 30mm
• Claimed weight: 1595g
• Actual weight: 1630g (including rim tape, valves, and centerlock rings)
• RRP: $2499 AUD/$1529 USD (including free global postage)

Note for customers in the USA: the price above includes Australian GST at 10%, which you won’t have to pay – yay!

An ‘Off-Road’ Specific Wheelset

When Curve launched its Dirt Hoops in 2019, it intentionally split the market. While other brands were dreaming up more hype to sell their new-fandangled down county and race-worthy gravel max rims as “the next great innovation in cycling,” Curve did what they do best: they cut the BS and focused on what matters. As they put it, “Dirt Hoops are designed for MTB, Gravel, Off-Road Touring Adventures, Mega Expeditions, Bike Packing, Basket Packing, Beard Packing – Whatever spins your wheels.”

Constructed from a blend of 3K and unidirectional T700, plus carefully placed T800 carbon fiber, Dirt Hoops share the same material properties as other premium rims in the market. But unlike other brands, instead of the skinny (2.5mm-3.75mm) bead profile found on most rims, Curve uses a beefy 5mm thick hookless bead. Having identified this as a key point of failure during Jesse’s smash tests, the team discovered that a chunky bead helped spread impact loads and lessened the chances of damaging a tire casing on a heavy bottom-out.

When I first saw the wheels, I have to admit, I was a little worried the stout bead might result in a tricky tire set up. But I couldn’t have been more wrong. They inflated with ease, sealed up perfectly, and never lost air during my tests. But, an exaggerated bead profile was just the beginning of the Dirt Hoops design story.

The second and perhaps biggest innovation for the Dirt Hoops is what Curve calls ‘Mo-Spo technology’. A playful name for the serious business of molded spoke hole technology, which essentially allows them to reinforce the spoke hole and nipple bed area with continuous strands of carbon fiber while reducing the bulk of unnecessary material in between spoke holes. In adding this extra carbon to the inside face of the spoke holes, Curve can maximize the rim’s strength, without adding excessive weight.

Mo-Spo also enables Curve to mold the spoke holes, not drill them like most carbon and alloy rims on the market. When drilling holes in carbon, you have to interrupt the carbon fiber weave, which weakens the overall structure of the wheel. Whereas, molded spoke holes produce fewer interrupted fibers and thus a stronger spoke nipple-to-rim interface. This approach can also be seen by other premium carbon rim designers like ENVE. However, one key differentiator (and law-suit avoiding decision) is that unlike ENVE’s design, which uses molded technology to embed the spoke nipple inside the rim, Curve stuck to its off-road roots and designed the Dirt Hoops with external nipples. These nipples are adjustable if you should ever run into problems while on trail or long tours (more on that later).

What’s Wider Than Wide? Widerrrr

Available in both 27.5 and 29” diameters, nearly every axle hub standard on the market, rim only or complete wheelset, and in two versatile rim widths – Wide 35, and the Wider 40 – there’s not many places, these hoops couldn’t take you.

The Wide 35 (named for its external rim width) is the lightest Dirt Hoop in the line up. More akin to an XC/gravel wheelset, its 25mm inner width works best with 1.75” – 2.5” tires (44 mm – 64 mm), according to Curve. The Wider 40 is the burlier sibling, and what I have been testing for the last few months. It has a 30mm inner width and (according to Curve) works best with 2.3” – 3.0” wide tires (58 mm to 76 mm).

For their complete wheelsets, Curve specs the uber-reliable DT Swiss 350, straight-pull hubs. Available with a 12 x 100 or 15 x 110mm thru-axle up front, and a 12 x 142 or 12 x 148mm rear, all you need to do is choose your freehub driver standard (SRAM XD, Shimano HG or Microspline) and ride off into the sunset. At the time of purchasing, Curve also offers the option to upgrade the hubs to the DT Swiss 240, which comes with the faster-engaging 36T Star Ratchet freehub, as opposed to the stock 18T Star Ratchet. I opted for the 29” Wider 40’s with the standard DT350 hubs and an XD driver. Earmarked for my GMX+ Steel, the carbon Dirt Hoops would be the perfect upgrade to the alloy version of the Dirt Hoops that shipped stock with the bike.

Challenging Popular Wisdom

Now I don’t profess to be a carbon wheel expert. I’m not an engineer and I’m an average wheel builder at best. But after bikepacking around the world – full time for five years – bashing, smashing, and obliterating rims from a range of manufacturers, I’ve learned that a good wheelset is worth its weight in gold. From my early days on classic touring rigs (with racks + panniers) to my current bikepacking setup, lots of the popular wisdom I’ve learned about building strong wheels for loaded bike touring seemed to orbit around one central claim: the higher the spoke count, the stronger the wheel. With this front and center, I’ve typically defaulted (and perhaps you have to) to burly alloy hoops, with 32/36 hole construction, j-bend spokes, and a strong hub.

Initially, I approached the Dirt Hoops with some hesitation. With my penchant for sending rims to an early graveyard and my own biases on spoke count, I doubted their featherweight, 28-hole construction. But honestly, I needn’t have worried. During their research and development phase, Curve experimented with various spoke counts before opting for 28 as the standard offering across their wheelsets. For Curve, a well-designed and built 28-hole wheel is the Goldilocks zone for the type of off-road, bikepacking, and dirt touring they like to do.

The lower spoke count amplifies the inherent comfort and compliance of carbon fiber as a material, while the combination of premium CX-Ray, straight pull spokes by Sapim, and the bomber DT Swiss 350 hub work seamlessly together to produce an insanely strong wheel.

When it comes to strength: the old j-bend vs. straight pull spoke argument will likely never be settled. Some people claim that as a j-bend spoke beds into the hub, it frets and ovalizes the spoke hole, which causes it to lose tension and eventually wears out the hub. Whereas, in a straight pull hub and spoke configuration, there is much less motion and therefore, less wear at both the hub and nipple, resulting in a stronger overall wheel.

Now, I don’t doubt that some of you might call BS on this, and honestly, I’m not in either camp right now, but after months of testing the Dirt Hoops on the rough and rugged trails of Northern Thailand, all I can say is that I’m yet to break a spoke or have any issues at all with spoke tension.

From Alloy to Carbon: Feeling is Believing

As noted earlier, my original goal with the carbon Dirt Hoops was to help shed some rotational weight from my GMX+ Steel, which shipped with Curve’s stock alloy Dirt Hoops. A solid adventure partner, the alloy Dirt Hoops have dealt with plenty of abuse, but at 2500g (including rim tape + valves) they’re hardly a light wheel. Whereas, their carbon counterparts top the scales at just 1635g (including rim tape + valves), shaving nearly 900g in overall weight.

Shod with a pair of Vittoria Mezcals in 29×2.6”, I tested the carbon Dirt Hoops on everything from techy singletrack and wide open gravel roads to steep AF dirt climbs. 900g of weight saved is an impressive number no doubt, but what I found even more impressive was the way they transformed the feeling of my rig.

The GMX+ is a big bike with a long wheelbase. It’s designed to feel decisively sure-footed and comfortable. However, as soon as I chucked on the carbon Dirt Hoops, it transformed from a kind of sluggish climber to an absolute rocketship. The rotational weight savings could be felt immediately and straight away I found myself climbing some of the steep (23-25%) dirt roads that I’d usually have to push. On the flats and downhills, they feel lively and incredibly comfortable. Soaking up the trail chatter and absorbing bumps with ease thanks to their chunky rim profile.

During my tests, I also tried to pay particular attention to any noticeable differences in the ride quality of the (new to me) straight pull and 28h design of the wheelset. Although these tests are nowhere near scientific and purely based on my anecdotal observations: I do feel that the straight pull design offers a more direct transfer of power compared to the j-bend alloy Dirt Hoops I’ve been riding up until now. However, this is something I can’t back up with any numbers, so please don’t come after me with pitchforks.

But wait, it can’t all be sunshine and rainbows right? While there’s a lot to like about this wheelset, I did notice one performance snag during my time testing. The stock DT Swiss 350 rear hub ships with an 18T Star Ratchet freehub, which feels fine on paved roads and champagne gravel, but once I started riding more technical trails and my local single track, I did feel some ‘pedal lag’ with the hub, which was a bit of a surprise. It’s not a huge issue, and it’s something you can easily upgrade without needing any specialist tools, but that said, for the price point of the wheelset and its off-road specific claims, I’d like to see Curve spec the 36T with the DT 350 and 54T star ratchet with the DT 240 upgrade straight out the box.

Finally, Curve offers a 5-year warranty on their carbon Dirt Hoops, plus a 50% crash replacement guarantee, if you destroy your beloved rims.

Pros

• Unique molded rim design creates a super tough, but lightweight wheel
• Mega versatility in different rim diameters, widths, and hub standards
• The beefy 5mm thick hookless bead, helps produce a strong and comfy rim
• Designed specifically for ‘off-road’ applications
• Offered with or without a dyno front hub as standard
• Straight pull design is great for ‘in the field’ maintenance
• Impressive weight (1635g) for such a sturdy wheelset
• Built around the ever-reliable DT Swiss 350 hubs
• Well-priced when compared to many other high-end carbon wheelsets.

Cons

• It would be nice to have a lifetime warranty on the wheelset
• Stock 18T star ratchet freehub felt a little laggy on technical singletrack

Wrap Up

Overall, I’m super impressed with the carbon Dirt Hoops. Their unique design and balanced weight to strength ratio really hits the sweet spot for me, and I can’t see myself switching back to alloy hoops anytime soon.

There’s no denying it, carbon hoops aren’t exactly a cheap upgrade to your bike, but having made the switch, I can absolutely confirm they are definitely one of the best upgrades you can make. The Carbon Dirt Hoops have transformed my bike both in terms of weight savings and its overall feeling to ride. I have complete confidence in their strength and plan to use (and abuse) them for all my upcoming trips this year, including a two month dirt tour in Peru.