Joe Robinson 7 Oct 2021
Specialized's Crux gets the Aethos treatment which sees it become the lightest 'gravel' bike on the market
Specialized has updated its off-road Crux model, borrowing technology learned from the development of the lightweight Aethos road bike to create what it claims is ‘the lightest gravel bike in the world’.
The new Crux, Specialized’s dedicated cyclocross race bike since 2011 (though it is now being branded a ‘gravel bike’), has been subjected to the same tube reconfiguration and repositioning of carbon layers as the Aethos, allowing the overall frame weight to drop to 725g (56cm), meaning a top-spec S-Works model will now weigh 7.25kg off the peg.
Add that to the increased tyre clearance from 33mm to 47mm and the retention of a performance-orientated geometry and Specialized is claiming this latest Crux will be ‘your one-way ticket to gravel enlightenment’, whatever that means.
Lightest gravel bike, ever
The headline news here is that the 2021 Crux has been on a serious diet. The previous S-Works model, now three years old, had a frame weight of 950g (56cm). This new bike with its S-Works 12r frameset sits pretty on the scale at 725g in the same frame size. That’s seriously light for a gravel bike. How did it get down to this weight? Well, it is all because of the UCI-illegal Aethos climbing bike.
In what he calls his ‘eureka moment’, Specialized engineer Peter Denk used Finite Element Analysis (FEA), a giant supercomputer and 1,000 simulations to reimagine tube proportions and efficient positioning of carbon fibres within the frame to arrive at the 585g Aethos frame. There is no fancy new carbon molecule mixture here, just a different way of looking at the same things.
‘How we taper the top tube, how we taper the down tube, the curvature of how we run into the head tube and the bottom bracket is extremely important,’ explains Denk.
‘If we follow those shapes, we get rid of all stiffness layers. Just with this shape, we can save 150 grams of composite weight.’
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For this new Crux, the total weight saving of 225g is a huge step forward in a world where margins are often much finer. It means a fully-built 56cm S-Works model with Roval Terra CLX wheels, 38mm Roval Pathfinder tyres and 1× SRAM Red eTap AXS weighs in at just 7.25kg, some 500g lighter than its equivalent predecessor and even lighter than some cut-and-dried road bikes.
This also means the new Crux frame is significantly lighter than the Open Wi.DE (1,025g), 3T Exploro RaceMax (1,050g), Cervélo Aspero 5 (1,100g) and Canyon Inflite (940g). It is also lighter than the newly released Trek Boone (950g).
Furthermore, the knowledge harvested in the development of the Aethos has been lifted and introduced here, the Crux being the next project Specialized had on the production line.
So when the Diverge gravel bike or Tarmac road bike come round to being updated, chances are lessons learned from the Aethos will be used there too. Which should mean lighter bikes all round.
Gravel bike or cross bike?
Back to the Crux, though, and a question Cyclist found itself constantly asking was: is the Crux actually a gravel bike? Is it not just a cyclocross bike, or are cyclocross bikes and gravel bikes effectively the same thing now? Or are cyclocross bikes just a subset of gravel bikes? Or does none of it really matter, simply the result of our persistence in ensuring everything has a label?
Specialized already services the ‘hero gravel market’ through the Diverge, which launched last year. What is ‘hero gravel’, you ask? Well, as the team at Specialized UK explained, this is the style of off-road riding you see on Instagram and in coordinated marketing campaigns.
Dusty, dry gravel roads that stretch for mile upon mile being ridden by guys and gals wearing denim shorts and jaunty neckerchiefs. Where the bikes are loaded with bags and the rider’s willingness to sleep on a roundabout is directly correlated to their enjoyment of bands like Tame Impala.
The Diverge has a slack geometry with stretched wheelbase, short reach and shallow head tube angle. It has provisions for 47mm 700c knobbly tyres and comes with more storage compartments and rack mounts than you can shake a stick at. Perfect for long, continuous days chomping off-road.
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The latest Crux is clearly here to serve a different purpose – to be ridden fast, frantic and for a short amount of time off and on road.
With regards to geometry, the new Crux is racy, aggressive and actually much closer to Specialized’s Tarmac road bike than to the Diverge gravel bike. On a 56cm frame, the stack is 578mm and the reach 397mm – just 1mm shorter in both cases than the Tarmac – giving you a low, stretched out aero position.
By comparison, the Diverge has a 610mm stack and 392mm reach. It also has a longer wheelbase to the tune of 9mm – 1042mm to 1033mm – all of which suggests a more upright and forgiving riding position.
Then there is the glaring omission of any suspension system on the Crux. Specialized has ignored its Futureshock stem suspension system, seen on both the Diverge and Roubaix models – a decision Specialized explained was made in order to maintain a lower front end.
In fact, if you opt for the S-Works model, the bike even comes specced with the ultra-light, ultra-rigid Alpinist seatpost, which goes some way to explain Specialized’s lack of provisions for comfort and compliance.
Specialized has purposely neglected eyelets for mudguards, racks and bags while also deciding against building in frame storage such as that used in the Diverge.
In fact, the only place in which the Diverge and Crux match up is tyre clearance. The Crux previously fit a 33mm tyre. Now, thanks to a straight, hollow drive-side chainstay, it can accept 700 × 47mm tyres or even 650b × 2.1in. Clearance, unlike the rest of the bike, suggests better capability in regards to tackling more terrains.
Specs and cost
The new Crux will come in a variety of spec options and price points. Top of the tree will be the S-Works edition followed by the Pro, Expert and Comp models. All apart from the S-Works variant with its 725g frame will use use 10r framesets weighing in at 825g (56cm). All models are sold with 1× groupsets while all models will be fitted with tubeless-compatible wheels and tyres. All will also be available in sizes 49cm through to 61cm.
Specialized S-Works Crux
Frameset: S-Works 12r
Groupset: SRAM Red eTap AXS w/ power meter (40/10-44)
Wheels: Roval Terra CLX w/ Pathfinder Pro 2bliss ready, 700 × 38c
Colour: Satin carbon
Specialized Crux Pro
Frameset: Crux 10r
Groupset: Sram Force eTap AXS (40/10-44)
Wheels: Roval Terra CL w/ Pathfinder Pro 2bliss ready, 700 × 38c
Colour: Coral Lilac Fade or Dusty Blue
Specialized Crux Expert
Frameset: Crux 10r
Groupset: Sram Rival eTap AXS (40/10-44)
Wheels: Roval Terra C w/ Pathfinder Pro 2bliss ready, 700 × 38c
Colour: White Speckled or Satin Forest
Specialized Crux Comp
Frameset: Crux 10r
Groupset: Sram Rival (40/11-42)
Wheels: DT Swiss G540 w/ Pathfinder Pro 2bliss ready, 700 × 38c
Colour: Arctic Blue or Satin Smoke
Digital editor Joe Robinson’s first impressions
I haven't done that much riding on the new Specialized Crux yet, but I have done enough to form some first impressions, and luckily the Crux left me with pleasant ones.
Last summer, I had the then-new Specialized Diverge to ride ahead of launch. In the heady, sun-drenched days of the first lockdown, the Diverge was the perfect accompaniment to those relaxed, evening rides where all I wanted to do was forget the world.
With its slack geometry and comfortable ride position, Futureshock suspension and provisions for 2.1in (53mm) tyres on a 650b wheelset, it simply buzzed over any terrain I dared to take it on.
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However, for the style of gravel riding that most of us tackle here in the UK – short, sweet and often single track rather than gravel – I couldn’t help but feel that riding the Diverge was like using a sledgehammer to crack a walnut. It made things too easy and ultimately sucked some of the fun out of riding off-road.
The Crux, I’m happy to report, has made off-road riding exciting again. The geometry is tighter, the ride position more aggressive and there is no suspension. These things actually make riding off-road challenging again. They also mean you ride a lot faster, which in my opinion is ideal.
Going uphill, whether on or off-road, there is snappiness to it that you seldom get in gravel bikes and when riding on flatter terrain, your speed holds much easier too, no doubt a combination of the lightweight, stiff frame and racing geometry at play.
One thing I also really loved was the tyre clearance. For the style of gravel riding available to me in the south-east, there is really little need for tyres wider than 42mm.
The 38mm pathfinders were just right, offering enough grip on the gnarly stuff without it feeling like rhino hide on tarmac. But because of the huge clearance left between bike and tyre, no matter how much mud and gunk was churned between the tyres and frameset, I was always able to keep rolling along.
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Yes, the longer head tube and shorter wheelbase make the bike less stable than the Diverge but the Crux was still perfectly capable of tackling terrain beyond its means – you just had to trust your bike handling more. And yes, I would not be keen to take this aggressive, sometimes harsh bike on a multiday off-road touring ride but I have no intention whatsoever of sleeping on a roundabout so would never use this bike in that way.
My idea of off-road riding is two to three hours of going as hard as I can on my local byways and singletrack while having unadulterated fun. This bike may just be an ideal partner in crime.
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