Specialized Aethos Comp review

The Specialized S-Works Aethos frameset is built from the brand's highest-grade FACT (Functional Advanced Composite Technology) 12r carbon.

The Specialized Aethos Comp is made from lower-spec 10r carbon, but uses the same moulds as the S-Works.

It weighs in at a claimed mere 699g, so is still one of the lightest production disc brake frames you can buy. It carries less weight than the 790g Tour-winning Colnago V3Rs and Cannondale’s 866g SuperSix EVO.

It’s not only lighter than Specialized’s 800g Tarmac SL7, it’s also a few grams lighter than the relaunched and lightened Cervelo R5, which now weighs a claimed 703g.

The Aethos Comp’s slender, round tube profiles and traditional shape (no dropped seatstays here) give the frame a retro flavour and its apparent disregard for aerodynamics seems at odds with Specialized’s commitment to reducing drag.

But make no mistake, beneath its retro looks and understated finish, this is a bike that’s on the cutting edge.

Rival sons

The Aethos Comp is built around SRAM’s 12-speed Rival eTap AXS groupset, which is SRAM’s most affordable wireless electronic road groupset.

When SRAM introduced wireless technology to its third-tier groupset, I was concerned that there might be too many compromises required to keep it at an appropriate price point.

But the Rival AXS uses the same electronic brain, the same motors and the same transmission technology as the higher-tier eTap groupsets (all of which are accessible and tuneable through SRAM’s excellent AXS app), while using less exotic materials to bring the price down.

The shift logic of AXS is simple: push the right button to move down the cassette, push the left button to move up it, and push both buttons together to shift between chainrings.

It doesn’t take long to become accustomed to this system, even if you’re a long-term user of Shimano or Campagnolo.

Shifts are just as quick as they are with Red and Force groupsets, and chain security over poorer surfaces is impressive too (the rear mech has a spring clutch that keeps the chain taut to prevent it from bouncing around).

Even on the more challenging surfaces of my Wiltshire testing routes, there were no issues.

Pair it with SRAM’s AXS app and you can record pretty much every metric you could want: speed (current, average and max), distance and trip time.

There’s also full GPS tracking and heart rate monitoring if you pair it with an HRM. The app also lets you adjust settings, from how many gears it’ll shift with a prolonged button press to full auto, which sees AXS automatically shift the front mech when you reach the top or bottom of the 12-speed cassette.

The bike is fitted with 48/35 chainrings (pretty much the equivalent of a 52/36 ‘pro-compact’ setup), although Specialized has given the Aethos a 10-36 cassette (equivalent to an 11-speed 11-34).

The Aethos’s wider-range cassette means you get single-tooth jumps between the top four sprockets (10, 11, 12, 13), with two-tooth jumps for the next four (15, 17, 19, 21) before finishing off with three- and four-tooth jumps (24, 28, 32, 36).

Even with the gaps, it still feels nicely progressive and the 35x36 bottom gear is more than ample for even the harshest climbs.

The Aethos Comp may lack the featherweight, 585g frame of the S-Works model, but its 699g frame is still extraordinarily light.

In fact, the new Aethos family may just be the career peak of Peter Denk, the composites engineer who also produced Scott’s ground-breaking CR1 and Addict bikes, and Cannondale’s UCI-baiting SuperSix EVO.

What Denk doesn’t know about making lightweight carbon bikes probably isn’t worth knowing.

Climbing prowess

While I was blown away by the climbing prowess of the S-Works Aethos (as you might expect with a 58cm bike weighing just 6.38kg – a full 420g less than is allowed for bikes being ridden in UCI races), its stiffness made it skittish on descents and poor road surfaces.

The Aethos Comp, however, is much better when it comes to descending – the chassis is more composed and the front end transmits much less buzz, even with an alloy bar, budget wheels and skinny tyres.

In this guise, the Aethos feels composed, balanced and more confidence-inspiring.

I’m not sure whether this is down to the frame’s 10r carbon having more give than the 12r carbon used to make the S-Works Aethos or the different wheels and components.

The Aethos Comp frame is just 115g heavier than the S-Works version (the fork has gained a few grams too), but it does seem to make for quite a different ride.

The bike responds to your pedalling input with plenty of spark and, even though its 1,670g wheels and modest tyres don’t exactly shout ‘climber’, it climbs as well as bikes that are a kilo lighter.

Swapping out the wheels for a 500g lighter pair of Zipp 303 Firecrests elevated the Aethos Comp to a machine that could beat a super bike up climbs.

It may have been designed not to comply with the UCI weight limit, but this Aethos still gets the ‘full-fat’ race geometry. The 58cm test bike has a low 591mm stack and a long 402mm reach.

Throw in a tight wheelbase, a tad over a metre, and a short, 55mm trail (shorter than those of Cannondale’s SuperSix EVO and Specialized’s own pro-level Tarmac SL7) and you’ve got a nimble, fast-handling machine.

Combine those numbers with the lightweight chassis and this is a bike you can flick in an instant to avoid potholes, ruts or other hazards with ease.

A lot to love

It’s a bit of a mixed bag when it comes to the Aethos’s contact points. The short Power saddle is great even in its near-300g Sport version (rather than the 160g model the S-Works bike gets).

The alloy bar has a smartly shaped, compact drop that’s easy to get down into but is quite slender, especially the tops, which feel narrower compared to the latest flattened, ovalised designs.

The bar is wrapped with Supacaz’s excellent tape, though, which is sticky, compliant, durable and a well-cushioned alternative to the skinnier, cheaper tapes found on a lot of bikes.

There’s a lot to love on Specialized’s Aethos Comp, which I think is much better value than its S-Works sibling. Its handling is lightning fast, it absorbs road buzz better than the S-Works model and is more composed over poor road surfaces as a result.

The Aethos Comp’s understated looks will appeal to many, its SRAM wireless shifting worked impeccably and the frame is one of the lightest you can buy.

I just would have appreciated a set of wheels that would really have made the most of its super-light frame, but that’s true of a lot of bikes, even at this lofty price point.

Specialized Aethos Comp geometry