curve dirt hoops wider 40 carbon wheels
10 Feb 2020

Curve Cycling has completely redesigned its Dirt Hoops carbon mountain bike wheelset and split it into two distinct versions; the Wide 30 and the Wider 40. We've been testing the burlier option of the two to see how they compare to the big names

The not-so-minor details

Product

Curve Dirt Hoops Wider 40

Price

$2,198

Weight

1637g

Positives

- Lightweight given the generous proportions
- Unique rim profile adds reinforcement where it's needed
- Nicely built with high quality spokes & hubs

Negatives

- Slow freehub engagement
- Doesn't include 6-Bolt adapters
- Crash replacement policy isn't as competitive as others

There’s a dizzying array of options out there in the mountain bike wheel market. Muddying the waters further, an explosion of new generation wheelbuilders over the past few years has disrupted the scene for the bigger and more established players. Fuelled by the advent of modern Asian-made carbon fibre rims, these smaller and often consumer-direct brands are producing well-spec’d wheelsets at more tantalising price points than the ENVEs of the world. Alongside the likes of Zelvy, Wheelworks, Black Cro and Hunt Bike Wheels, Curve Cycling is one of the smaller names that are sticking it to the big guns.

curve dirt hoops wider 40 carbon mountain bike wheels
New from Curve Cycling, the Dirt Hoops wheelset makes use of a unique carbon fibre rim profile.

Based in Melbourne, Curve is a rider-owned and rider-led company that places a significant emphasis on in-house product development and testing. Having amassed over six years of wheelbuilding expertise, Curve’s product line has steadily grown to include standalone carbon fibre rims and complete wheelsets that cover road, gravel, touring and mountain bike applications. Additionally, Curve also produces frames – including the titanium DownRock we recently reviewed.

While Curve’s previous wheelset offerings have utilised open-mould rim designs, it’s a different story with the Dirt Hoops. The carbon fibre layup and profile is unique to Curve, and it’s offered in two different versions; the Wide 35 (for XC/gravel), and the Wider 40 (for trail/AM). Over the past three months I’ve been testing two sets of the Wider 40 wheels, which are only available in a 29in diameter. Here’s how we’ve got on with them.

curve dirt hoops wider 40 carbon mountain bike wheels
The Dirt Hoops come in two distinct versions; the Wide 30 (XC/gravel) and the Wider 40 (trail/AM).

First Impressions

Constructed from 3K and unidirectional Toray T700 carbon fibre, the Dirt Hoops Wider 40 rims measure 40mm externally, and 30mm internally. They also employ significantly thicker sidewalls than what we’ve seen from Curve’s previous designs. The fat, hookless beads aim to increase impact strength, and their blunt shape is also less likely to damage a tyre casing in the event of a harsh pinch-flat.

During the layup process, additional layers of carbon fibre are built up around each spoke hole. Called ‘Mo-Spo technology’, the added material aims to improve strength where it’s needed, while ensuring the weight increase is kept to a minimum.

curve dirt hoops wider 40 carbon mountain bike wheels
Measuring 40mm externally and 30mm internally, the Dirt Hoops have a thick and generous rim shape.

Speaking of mass, Curve claims a standalone Wider 40 rim weighs 440g. If you want to go lighter, the narrower and more XC-oriented Wide 35 drops down to 385g per rim. Rims are available on their own for $729 each.

For the complete wheelsets, Curve builds the Dirt Hoops rims with 28 Sapim CX-Ray spokes per wheel. They’re laced to DT Swiss 350 Straight Pull hubs, which are only about 40g heavier than their 240s equivalent. If you really want 240s though, Curve offers that as an upgrade option. Complete weight for our Wider 40 test wheels with tubeless tape and valves fitted is 1636g, which is impressively light given the generous rim proportions and hard-hitting intentions.

Price for the complete Dirt Hoops wheelet is $2,198. They’re sold both direct via the Curve Cycling website, and through dealers around Australia.

Setting Up

With a 30mm inner width, Curve recommends running tyres 2.3-3.0 inches wide. In my experience though, 2.4-2.6in tends to be the sweet spot for a 30mm wide rim. Narrower tyres can square off too much, which pushes the bare sidewalls out further than the tread itself, while also deadening the ride quality. At the other end of the scale, wider tyres create more of a lightbulb effect, and exhibit more wobble and casing flex through the turns.

For our test wheels, I’ve tested them with a 2.3in wide Maxxis Minion DHF/DHR2 combo, a 2.4in wide Pirelli Scorpion M/R combo, and 2.6in wide Bontrager XR4 Team Issue tyres. All of which setup tubeless easily without need for an air compressor.

I also tested a second set of Wider 40 wheels, which came fitted to the Curve DownRock hardtail. This wheelset came wrapped with e*thirteen tyres that were hella tight to get on and off. That was no fault of the rims though – those tyres were tight on every wheel I tried them on.

2020 trek fuel ex 9.8 curve dirt hoops wider 40 carbon mountain bike wheels
We mostly tested the Dirt Hoops Wider 40 wheelset on a Trek Fuel EX 9.8.

The 350 hubs utilise a Centerlock rotor spline, which is a neat system when you have a matching Centerlock rotor. Unfortunately Curve doesn’t include 6-bolt adapters with the wheels though, so you’ll have to pony up for those separately if you’re sticking to 6-bolt discs.

Being a DT Swiss hub though, spare parts – including Shimano Micro Spline drivers – are readily available, and they’re also a doddle to pull apart and service. The freehub body seal is still too loose though. On several occasions while I had the rear wheel out of the frame, the cassette would accidentally slide off the axle, bringing the freehub body with it. Having to find the Star Ratchet plates on the ground and then clean the dirt off them before reinstalling is terribly annoying.

DT Swiss 350 hubs feature front and rear.

On The Trail

Having first found their way onto my Trek Fuel EX 9.8 long-term test bike, the Dirt Hoops Wider 40 wheelset dropped a significant amount of rotational weight off the stock Bontrager carbon wheels (1908g including rim strips and valves). The difference in speed was immediately noticeable. Not just with zippier acceleration, but also with handling too.

Since lighter wheels tone down the gyroscopic effect, directional changes become just a little bit easier and a little crisper. On trails with repeated S-bend chicanes, the whole bike felt more willing to flip-flop through the turns. The stiff rims and taut build also contribute to the Wider 40 wheelset’s overall fervour.

In terms of ride feel, they’re not the clangiest carbon wheelset I’ve ridden. The Wider 40 rims measure 27mm tall, and the profile is quite round and blunt, which helps with radial compliance. They’re certainly smoother than the deeper Bontrager rims, which are quite harsh in comparison. However, the Curve’s are still a ways off the bump-soothing capabilities of the superb Crank Brothers Synthesis and ZIPP 3ZERO MOTO wheelsets.

curve dirt hoops wider 40 carbon mountain bike wheels
The Mo-Spo technology is invisible from the outside, but it’s an important feature. This sees the carbon fibre layered thicker around each spoke hole for added strength and durability.

I also back-to-back tested the Wider 40s with a DT Swiss EXC 1200 wheelset I’m also testing at the moment. Both have a 30mm internal rim width, and I set them up with an identical Maxxis Minion DHF/DHRII tyre combo inflated to the same pressures. Riding on the same test loop, I can’t say there was a perceivable difference in terms of overall rigidity. Both wheels exhibit the crisp feel one can expect from carbon rims, with a more direct connection between the bike’s contact points and the tyres compared to an alloy wheelset.

One thing I did notice though was how much slower the 18T Star Ratchet freehub is in the Curve wheelset. On technical ascents, the pedal lag is noticeable and distracting. For this reason, I’d like to see Curve use the faster-engaging 36T ratchet kit, especially given the $2K+ pricetag.

curve dirt hoops wider 40 carbon mountain bike wheels dt swiss 350 hubs
Engagement from the 18T ratchet mechanism is noticeably laggy.

Durability

Throughout three months of testing, the Wider 40 wheelset spent plenty of time being hammered on our Fuel EX long term test bike, as well as the DownRock hardtail. While I sliced up a rear tyre during that time with a particularly heinous pinch-flat, the rims have emerged out the other side largely unscathed.

One rear rim did suffer a nasty external rock strike, presumably after a rock was flicked up by the front tyre while bombing down one of my local rim-dinging descents. That was a particularly unlucky event, though it’s proof that while carbon rims can often withstand higher loads than a comparable alloy rim, they can still be damaged.

curve dirt hoops wider 40 carbon mountain bike wheels crack damage
The rims have copped an absolute flogging over the past few months. An unlucky and largely superficial rock strike on the rear wheel is the only damage they’ve sustained during that time.

With that in mind, I fitted a Vittoria Air-Liner to the rear wheel of the DownRock hardtail partway through testing. As well as protecting the expensive rims, the insert also allowed for lower tyre pressures for more grip and comfort. I’m a big fan of tubeless inserts. Even though they add weight and rolling resistance, they’re well-worth considering, especially if you own a high-end wheelset.

Neither of the Wider 40 wheelsets has required any attention with a spoke key – a sign of sturdy rims and a well-balanced build. If you do need to true them, Curve has used external brass nipples for practicality and durability.

curve downrock titanium hardtail wil harcourt
We’ve also been testing the Dirt Hoops wheelset on Curve’s own DownRock titanium hardtail. See the review of that bike here.

The Competition

At over two grand, the Curve Dirt Hoops wheelset does hover around a similar price point to carbon wheels from some big-name competitors. That includes the excellent, if un-lustworthy, Giant TRX 0 wheelset, which is identical in cost and weight, but is built with higher quality 240s hubs. Ride quality is very similar between the two, and the Giant carbon rims feature similar engineering detail with internally reinforced spoke holes.

You could spend $800 more and get the $2,999 DT Swiss EXC 1200 wheelset, which rolls on the uber-trick 180 hubs with their smoother-than-butter SINC ceramic bearings and the new Ratchet EXP freehub mechanism.

Or you could spend $400 less and get the value-packed $1,800 Bontrager Line Pro 30 wheelset, which comes with a 2-year no-questions-asked crash replacement policy.

On that note, while the Dirt Hoops do have a generous 120kg max rider weight limit, Curve currently only offers a 2-year warranty to cover you for any manufacturing defects. When brands like Santa Cruz and Reynolds are leading the game with lifetime crash replacement guarantees on their carbon wheelsets, we’d love to see Curve offer more aggressive aftermarket support given the price point.

Flow’s Verdict

With their new unique rim profile, the Dirt Hoops Wider 40 is a generously proportioned carbon wheelset that’s ideally suited for 2.4-2.6in wide rubber. They’re built to a high standard with quality spokes and hubs, giving them a taut and responsive feel on the trail.

The competition is fierce at this price point though, and other brands are pushing hard with better crash replacement policies. Curve could certainly add further value to the Dirt Hoops with a faster-engaging 36T ratchet kit, along with 6-bolt rotor adapters and some spare spokes in the box.

Pricing and value aside, I do like that Curve has steered away from proprietary components in the first place, which can’t be said of some of its competitors. That makes it a solid and easy-to-live with carbon wheelset that has stood up well in the durability stakes, while being impressively light given its hard-hitting intentions. If you’re looking to buy a quality wheelset from an Australian company rather than one of the big brands, then these will surely be on your list.

curve downrock titanium hardtail dirt hoops carbon wheels rim
The Dirt Hoops is impressively light given its hard-hitting intentions.

Mo’ Flow Please!

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