Argon 18 Dark Matter Force AXS XPLR review

The Argon 18 Dark Matter Force AXS XPLR sets out to be a racer and rugged explorer combined.

It certainly excels in one of those camps, thanks to its compliant ride quality and comfortable position, not to mention its myriad fittings for bottles and bags.

The package Argon 18 has put together, with impressive Hunt wheels and SRAM’s excellent Force AXS XPLR is worthy of praise.

Though the endurance-biased position appeals to me, I’m not convinced it will go down as well with gravel racing fans, who may wish for a more aggressive ride position.

Argon 18 Dark Matter Force AXS XPLR frameset details

Argon 18 describes the Dark Matter as a “true performance gravel bike”, equally at home as a gravel race bike and a rough rugged adventurer.

That's quite a bold claim, though the frame and fork certainly combine elements of both sub-disciplines of gravel riding.

The frame is designed using Argon’s TCS protocols. TCS, which stands for ‘Topological Compliance System’, is the brand’s design method. It's claimed to optimise frame design and tube shaping with the physical properties of carbon fibre.

This, it’s claimed, is used to maximise stiffness where needed and introduce more compliance where vibration damping is preferable.

Applied to the Dark Matter, if you draw an imaginary straight line from the top of the head tube down to the rear axle, Argon 18 says everything below that line is maximised for stiffness, which results in more accurate steering and optimal power transfer.

Above the line, the top tube, seat tube, and seatstays are all designed to deliver compliance and absorb vibrations.

At the front, the tapering fork, with its forward sweep in its lower third, is designed to absorb chatter while maintaining steering accuracy.

The frameset maxes out on the fittings you would expect (unlike the Riverside GCR and Cervélo Áspero I tested alongside the Argon 18).

That means front and rear mudguard mounts, top tube bento box mounts and six bottle bosses on the down tube, which can sport a frame bag in addition to two bottles.

The seat tube also has twin bottle mounts and, up front, there are triple ‘anything’ mounts on the fork legs.

The underside of the down tube has a protective plate above the bottom bracket to guard the carbon from rock strikes.

The dropped chainstays and broad-crowned fork bring 45mm of tyre clearance (compared to the Áspero’s 46mm), although the space afforded by the fork hints that you might be able squeeze in something a little larger, if you really want.

The front end features Argon 18’s proprietary 3D head tube system. This means internal brake hose routing and integrating the headset top into the frame itself.

There are two options for the 3D top piece – I opted for the 0mm option because that suited my fit. If you prefer a taller front end, Argon 18 also offers a 25mm-tall version, which heightens the stack without compromising the front end’s looks or stiffness with stacks of spacers.

This can be chosen free-of-charge at point of purchase.

The frame accepts a standard round 27.2mm seatpost and spins on a press-fit 86.5 bottom bracket standard.

A fully painted frame with all the hardware (18 bottle-boss bolts, 3D head tube spacer, the seat clamp and rear derailleur hanger) is said to weigh 1,230g for a size large, plus 480g for the fork.

Argon 18 Dark Matter Force AXS XPLR geometry

The Dark Matter takes its inspiration from road-going bikes rather than mountain bikes.

That means a steep 73.1-degree seat angle and 72-degree head angle for my size-large test bike. These are the sort of numbers you’d expect of endurance bikes – and they should deliver handling characteristics that will appeal to gravel racers.

The stack is taller than the Cervélo and Riverside, at 609mm, but it also has a generous reach at 397mm (if you opt for the 25mm 3D headset topper, that stack rises to 632mm and the reach shortens to 390mm).

The long 428mm chainstays and long 104.6cm wheelbase make for a bike that’s about stability in the rough.

Argon 18 Dark Matter Force AXS XPLR build

The Dark Matter Force AXS XPLR is the range-topping model and the build reflects that.

The heart of the bike is SRAM’s latest Force AXS XPLR groupset. It’s a step up from the Rival AXS on the Cervélo, while the Riverside has old Force AXS eTap XPLR.

The gearing is speed-oriented, mating a 42-tooth chainring with a 10-44t XPLR cassette. That makes for a bike with lots of speed potential on road, and decent range off-road.

The bike rolls on Hunt’s broad 42 Limitless Gravel Disc wheels, which are 42mm deep and combine a 35mm external width with a 25mm-wide internal channel.

Hunt says these dimensions deliver aerodynamic advantages while running 38-40mm gravel tyres.

Suitably, these are wrapped in Vittoria’s Terreno Mix 700x40c tyres. It’s worth noting that the Terreno Mix tyre is a running change – originally this model was destined to come with the Terreno Dry, but we’re told Argon 18 responded to feedback from riders, who preferred an all-round tyre – something, we think, plenty of other brands could learn from.

The rolling stock comes set up tubeless, another plus point for the best gravel bikes.

Up front, FSA provides its workhorse OS-99 alloy stem and the cleverly shaped A-Wing Pro AGX bar. The alloy bar combines a flattened ovalized top section with a subtly flared compact drop. The top also has a slight rise.

The bar is wrapped with excellent Ciclovation bar tape that’s tacky to the touch and offers lots of cushioning.

Argon 18 provides its carbon TDS seatpost, which is clamped in place with a simple external binder (rather than a more complicated hidden clamp).

This is topped with Prologo’s Scratch-M5 AGX saddle, with its short dimensions. This AGX (gravel) version slightly beefs up the padding but maintains the same minimal shape – I’ve found it to be comfortable in the past.

Argon 18 Dark Matter Force AXS XPLR ride impressions

The Argon 18 Dark Matter is a very interesting proposition – on mixed surfaces, it’s quick and smooth.

It rides like a great endurance bike on the road and the taller gearing than its rivals gives it the edge when it comes to maintaining road bike pace on steep inclines.

Get it into its natural habitat and it’s a winner too, with a subtly compliant feel on gravel that’s superior to the Riverside GCR, especially when things get rough and chattery. However, it doesn’t have quite the refinement of the Áspero in that regard.

At the rear, it feels a match for the Cervélo, but up front it's a little harder, despite having a well-shaped bar and great bar tape.

It becomes obvious the Cervélo has the edge here thanks to its high-quality carbon bar. I think it would be an upgrade worth making on the Dark Matter.

The Dark Matter handles technical terrain and chunky gravel very well. It takes a lot to get the bike unsettled handling-wise, albeit it’s not quite as flickable and fun as the Cervélo.

However, it’s not too far off the pace and it's certainly an entertaining bike to ride on the limit, rather than a ‘scary’ one.

The Hunt wheels are fast yet forgiving, with a quick freehub pickup of only 7.5 degrees. The Terreno Mix tyres, with their broad-spaced knobs on the shoulders and well-spaced central tread, perform well in damp conditions, but don’t feel compromised in the dry or on tarmac.

They’ve fast become my favourite option of the Terreno range and a tyre I’d be happy to run on my own gravel bike year-round.

The Dark Matter is a great long-distance gravel bike. The slightly more relaxed ride position, compared to the Cervélo Áspero and Riverside GCR, made big endurance rides less stressful on my body, and the impressive contact points only bolster that. A carbon bar would further improve things.

When you factor in the multitude of fittings, this Dark Matter is definitely more of a mile-eating monster than a sprint-for-the-line racer.

Argon 18 Dark Matter Force AXS XPLR bottom line

Argon 18 may pitch the Dark Matter as both bikepacker and gravel racer, and that’s not far from the reality. That said, it feels more like an endurance gravel bike rather than a shorter-form race bike.

Its comfort and practicality make it a star performer for those looking to go long and over multi-day events.

Although the geometry and stable handling wouldn’t disadvantage all but the fastest riders in the heat of competition, it’s not quite the out-and-out racer the Áspero is – but then the Cervélo couldn’t carry a transcontinental payload.