Hot on the heels of Cervélo’s S5 aero race bike comes the American company’s new gravel racer, the latest Áspero-5. It’s appropriate: the gravel bike is the result of Cervélo applying its WorldTour-honed aerodynamic nous off-road, and the frame has been radically transformed versus its predecessor.
A once slender silhouette has morphed into a beefier shape with a tyre-hugging seat tube and deepened head tube that, while it doesn’t extend to the bayonet steerer extreme of the S5, is clearly inspired by its design.
‘The new Áspero-5 is a no-holds-barred aero race bike but optimised for off-road use,’ says Cervélo’s engineering manager, Scott Roy. ‘It’s intended to appeal to three categories of rider: serious gravel racers, “dirt-curious” roadies and European cycling enthusiasts.’
Roy says the first group are the types that drive the North American gravel scene and are up at midnight to enter the Unbound lottery, while the second group, still of US persuasion, are late to the idea you can ride bikes off-road but ‘a gravel bike that looks like a Cervélo S5 might be just the thing to push them over to the dirt’.
As for the European enthusiasts, ‘Speed and stiffness are critical factors for these riders, so a gravel bike that speaks road language fluently will appeal to them,’ says Roy. Bikepackers look to be deliberately left out in this case.
Cervélo Áspero-5 design and build
Cervélo highlights the Áspero-5’s aerodynamics, claiming it’s 37 watts more aerodynamically efficient than its predecessor and 34 watts more efficient than its nearest competitor at 45kmh. However its testing, which is as yet unpublished, did not set the Áspero-5 against aero-optimised rivals such as the 3T RaceMax or Factor Ostro Gravel.
The semi-integrated, two-piece cockpit delivers six of these watts savings, according to Cervélo. A proprietary C-shaped steerer makes room for the brake cables to pass internally through the stem into the frame, keeping them out of the wind but keeping the head tube narrow. Adjustability is not forsaken for aerodynamics though. The split spacers mean changing bar height is straightforward and you can alter bars and stems individually.
Despite adding depth to the head tube and down tube, and oversizing the bottom bracket junction for stiffness, Cervélo claims the Áspero-5 is 66g lighter than before, which Roy says is down to a more refined carbon construction.
The internal down tube storage compartment isn’t the roomiest but still holds two pouches for an inner tube, tyre lever and CO2 canister. Similarly, in line with the brand’s ‘haul ass not cargo’ slogan, the only other bolts are on the top tube to attach the low-profile bento box supplied with the bike.
This range-topping model weighs a svelte 7.78kg in size 58 and comes with a mullet drivetrain that pairs a 12-speed SRAM Eagle 10-52t cassette with a 48t chainring. Asked why Cervélo didn’t use SRAM’s latest 13-speed gravel groupset, with its 10-46t cassette and 46t largest chainring, Roy says, ‘Pairing a wide-range cassette with a larger chainring ensures the racer has the gears to climb while also providing the top-end speed for the race to the line.’
Similarly idiosyncratic is the choice of tyres. The Áspero-5 comes specced with Vittoria Corsa Pro Control tyres in an exclusive 42mm width. While they are gravel bike wide, they are also road bike slick, meaning they proved useless in wet conditions off-road and I had to swap them for knobblier 45mm Vittoria Terreno T50s.
Cervélo Áspero-5 geometry and riding
The Áspero-5’s stretched and low front end marks it out as a gravel race bike. Likewise the rest of its geometry is a touch more aggressive than all-round gravel bikes. Short chainstays and wheelbase work to increase reactivity, while the fairly generous 78mm bottom bracket drop coupled with the moderate 65mm trail (on 45mm tyres) both serve to improve stability, providing control while leaving the steering fast enough for high-speed manoeuvres.
The Áspero-5 also showcases modern bike fit trends. Shorter-than-standard cranks and a zero offset seatpost partially counteract the slackish 72.6° seat tube angle in an attempt to introduce biomechanical benefits such as opening the rider’s hip angle.
It’s a bike made for high speeds on fine, smooth gravel. Fortunately there is plenty of that on Cannock Chase, not far from my home, and after multiple test rides I came away extremely impressed by the Áspero-5. Overall it outperformed the Cinelli King Zydeco 2 by seeming similarly fast while being significantly more forgiving on chunkier stones. I felt like I could hit the ideal line through flowing S-bends at speed and feel nicely planted.
There was no give from the frame while pedalling, but there was also a feeling of compliance, which I suspect comes from the Reserve 40|44 GR wheels. They seem less harsh than many deep gravel rims, especially combined with the wider Vittoria tyres.
I couldn’t tell you how many watts Cervélo’s aero cockpit saved me, but to my mind it’s more significant that the stem and handlebar are separate, adjustable and ergonomic. I could comfortably rest my wrists on the handlebar tops in the ‘aero hoods’ position, and I didn’t get any of the numbness that can come from super-stiff one-piece handlebars.
Due to its reactive handling, dropping down loose and greasy descents required more concentration than with some gravel bikes, but they were manageable if I took my time, and when fitted with the 45mm Terreno tyres the bike could cope with gnarlier trails as well. Thanks to the apparent aerodynamic efficiency of its frame and geometry, it didn’t seem to give much away to a fast endurance bike on the road, so on a mixed terrain gravel ride I suspect you’d make up the time on tarmac you lost on technical stretches.
Tyre clearance and gearing
While some brands’ stated maximum tyre width is conservative, when Cervélo says 45mm it means it. The tiny smidgen of space between the rubber and frame and fork led me to believe the 45mm tyres had blown out wide on the broad rims, but a Vernier calliper indicated they hadn’t. It’s the kind of gap that could get clogged with mud or stones, so be careful riding on looser surfaces when you’ve maxed out tyre clearance.
With a biggest gear (48/10) identical to SRAM’s road bike groupsets, you’ll have little fear of spinning out on descents. More importantly, at higher gravel speeds of 30-35kmh, the chainline is fairly straight and efficient. However, thanks to its very low 48/52 bottom gear, low weight and dextrous handling, the Áspero-5 is also a match for steep tracks.
For £10,000 you might hope for the latest SRAM Red XPLR AXS, but the older version’s inclusion is justified by the wider gear range. And the validity of Cervélo’s claims about the Áspero-5’s aero performance are incidental to the impression that it fizzes on easier gravel. Unless you want wider than 45mm tyres, it’s got to be one of the best premium gravel race bikes around.
The reviewed spec
Model: Cervélo Áspero-5 Red AXS 1
Price: £10,000
Weight: 7.78kg (size 58)
Groupset: SRAM Red AXS
Deviations: SRAM XX SL Eagle AXS rear derailleur, SRAM XX SL Eagle chain
Wheels: Reserve 40|44 GR
Tyres: Vittoria Terreno T50 45mm (Vittoria Corsa Pro Control TLR 42mm tyres on stock bike)
Bars: Cervélo HB16 Carbon
Stem: Cervélo ST31
Seatpost: Cervélo SP27 Carbon
Saddle: Prologo Nago R4 PAS Nack
More info: cervelo.com