Specialized Tarmac SL8 Pro – SRAM Force eTap AXS review

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The Specialized Tarmac SL8 Pro is designed to distil the magic of the flagship S-Works version into a more keenly priced package.

With an impressive frameset and a solid build, the Tarmac SL8 Pro (SRAM Force AXS) is fast, light and exciting to ride.

Slightly narrow tyres and noisy disc brake rotors aside, it’s hard to fault the Specialized's 2024 Race Bike of the Year contender in terms of performance or spec.

The £8,000 / $8,500 / €8,500 price tag remains a significant barrier to entry, though, while there are similar options available for less from other big-name brands.

However, it’s much better value than the S-Works version and offers all the performance most riders will ever need.

Specialized Tarmac SL8 Pro – SRAM Force eTap AXS frame

The changes for the Tarmac SL8 from its predecessor, the Tarmac SL7, are modest at a glance.

The most obvious alteration is the updated front end, which Specialized says was inspired by its old aero road bike, the S-Works Venge.

Specifically, Specialized added a nose cone, extending the head tube forward of the steerer to lengthen the head tube’s aerofoil shape and reduce drag.

Specialized calls it the ‘Speed Sniffer’, which sounds a bit daft, but if it’s effective, perhaps that’s all that matters.

At the rear of the bike, the changes appear more subtle, but are more obvious when riding the bike. Taking inspiration from the S-Works Aethos, Specialized’s featherweight climbing bike, the back end of the Tarmac SL8 has been slimmed down dramatically to save weight and improve comfort.

Specialized says this narrowing of the rear end brings a small aerodynamic improvement, too.

The claimed weight for the Tarmac SL8 Pro frameset, which is constructed from Specialized’s second-tier Fact 10r carbon fibre, is an impressive 780g in a size 56cm.

That’s 95g heavier than the S-Works Tarmac SL8 frame (made using the brand’s top-level Fact 12r carbon) but, perhaps most notably, 20g less than the S-Works version of the Tarmac SL7.

The bottom bracket, head tube and fork are also said to have been stiffened, for improved pedalling responsiveness and sharper handling respectively.

The bike uses a BSA threaded bottom bracket standard.

Specialized Tarmac SL8 Pro – SRAM Force eTap AXS geometry

Existing fans of the Specialized Tarmac will be reassured to find out little has changed when it comes to the geometry and handling for the latest SL8 version.

As before, the Tarmac SL8 Pro is racy, with a long 393mm of reach and an aggressive 565mm of stack on the size-56cm bike I tested.

Compared to some of our other 2024 Bike of the Year race category contenders, a size-medium Canyon Ultimate CF SL has stack and reach figures of 560mm and 393mm, respectively, while a Focus Izalco Max measures 571mm and 399mm in a size L/56.

Continuing with the racy theme, the seat tube and head tube angles on the Tarmac SL8 are both relatively steep, at 73.5 degrees each, while the trail is short at 55mm for quick steering.

Though most bikes we saw at last year’s Tour de France were equipped with long and narrow cockpits, Specialized still specs an old-school 42cm-wide handlebar on this size-56cm bike, plus a relatively short -6 degree, 100mm stem.

Fortunately, the Roval Rapide handlebar is available in sizes from 38 to 44cm (in 2cm increments), while the Tarmac SL7 stem can be had in lengths from 70 to 140mm and in -6 or -12-degree angles.

In contrast to consumer-direct brands such as Canyon, a Specialized dealer may be willing to swap to a different bar width or stem length at the point of purchase if you have strong feelings on this topic.

Specialized Tarmac SL8 Pro – SRAM Force eTap AXS specification

The build spec of the Specialized Tarmac SL8 Pro (SRAM Force AXS) is, groupset apart, made up of components from Specialized and its house brand, Roval.

The front end on the Tarmac SL8 Pro is ported directly from the Tarmac SL7 – there’s no fully integrated Roval Rapide cockpit here. For me, that’s no issue, though.

The separate aluminium stem and aerodynamically shaped Roval Rapide carbon handlebar, are easier and cheaper to adjust or swap out (which is critical for an optimal bike fit), and are offered in a wider range of options than the pricier integrated bar.

My only reservation is that the ‘old’ stem doesn’t look as well integrated with the new Tarmac SL8 frame as it did on the SL7.

With the ‘Speed Sniffer’ extending out in front of the fork steerer, the stem appears awkwardly set back on top of the frame, especially when using a few headset spacers underneath it. This doesn’t affect how the bike performs, however.

The wheelset is Roval’s highly rated Rapide CL II, which pairs a set of progressively shaped, 51mm- and 60mm-deep rims with DT Swiss 350 hubs and DT Swiss Revolution spokes.

These are shod with S-Works Turbo 2BR tyres – among the best road tubeless tyres – in a size 700x26c.

Both the tyres and rims are tubeless-ready, but Specialized ships them set up with butyl inner tubes.

The saddle is also from Specialized’s own stable, in the form of its Power Pro – one of our favourite short-nosed saddles.

As the bike’s name implies, the groupset is SRAM Force AXS. This build pairs a set of 48/35-tooth chainrings with a 12-speed 10-33t cassette, which offers both a bigger top gear and a smaller lowest gear than a 52/36t crankset paired with an 11-32t cassette.

Specialized also includes SRAM’s Force AXS power meter, which uses the same internals as the excellent Quarq DFour DUB. As a spider-based power meter, it measures the total power produced by both legs.

I’m not a fan of the integrated chainring design, though. Effectively, this makes it a disposable item, because the whole unit will need to be replaced when either of the chainrings eventually wears out.

Overall, the size-56cm Specialized Tarmac SL8 Pro model I tested weighed 7.46kg – just 20g over the 7.44kg claimed weight.

Compared to some of its competitors, the Tarmac SL8 Pro is relatively expensive.

At £8,000 / $8,500 / €8,500, it’s £1,601 more expensive than the Giant Propel Advanced Pro 0 AXS. You can likewise get a similarly equipped Canyon Aeroad CF SLX for £6,299 / €6,599.

Both are around 400g or so heavier than the Tarmac SL8 Pro, but it’s debatable whether that alone justifies the difference in price.

That said, the Tarmac SL8 Pro is a decent chunk cheaper than an equivalently specced Trek Madone SLR Gen 7, and offers much better value than the £12,000 / $14,000 / €14,000 S-Works Tarmac SL8 with Shimano Dura-Ace Di2 R9200. The performance gained by spending the extra £4,000 to get the pro-spec version is likely to be marginal at best.

Specialized Tarmac SL8 Pro – SRAM Force eTap AXS ride impressions

On the road, the Specialized Tarmac SL8 Pro (SRAM Force AXS) is mostly a lot of fun to ride.

Given Ashley Quinlan’s review of the S-Works version was full of praise, I went in with high expectations and I wasn’t disappointed.

Thanks to the steep angles and slightly shorter-than-usual stem, the Tarmac SL8 Pro’s handling feels lively and engaging, but doesn’t tip over into nervousness when riding at high speed.

The Roval wheelset also adds a lot of performance to the bike. I tested the Tarmac SL8 Pro over a number of wet and windy days, and never felt concerned about the effect of such deep rims on the bike’s handling.

With its low weight, aero features and high-end finishing kit, it should come as no surprise the Tarmac SL8 Pro is a fast bike, but its comfort impresses too. The slim rear end is notably compliant, even with the narrow (by modern standards) 26c tyres.

That said, I still prefer wider tyres for the improved confidence and grip they offer on rough roads. 26c tyres are aerodynamically optimal for the Roval rims, according to Specialized, but away from smooth tarmac I missed the larger 28c tyres most road bikes are now specced with.

Fortunately, with the frame and fork having room for 32mm-wide tyres, there’s plenty of scope to size up if you want to.

The updated shifter shape is the most notable improvement to SRAM’s second-tier wireless electronic groupset, but it puts in an impressive overall performance in terms of shifting and ergonomics.

There’s very little to separate it from Shimano’s Ultegra Di2 R8100 groupset, in fact, though a Tarmac SL8 Pro with Ultegra Di2 is available for the same price if you simply prefer Shimano.

The only low point was that the SRAM Paceline brake rotors were excruciatingly loud during braking whenever the roads were wet and mucky (which, in the UK in early March, was practically every day).

They honked so loudly that riding through populated areas or on shared-use paths felt like playing Untitled Goose Game.

Anti-social noise and embarrassment aside, encountering horses or other vulnerable road users required extreme caution to avoid startling them.

The brakes were perfectly quiet in dry conditions, and stopping power and feel remained excellent throughout, but the noise in wet conditions was unbearable at times.

Were this my bike, I would look to swap these rotors out for something better immediately.

Specialized Tarmac SL8 Pro – SRAM Force eTap AXS bottom line

Overall, the Specialized Tarmac SL8 Pro (SRAM Force AXS) reminds me a lot of BikeRadar’s 2023 Aero Road Bike of The Year, the Giant Propel Advanced Pro.

It’s light, fast and comfortable but, for those who live in the UK, would be improved by a switch to larger tyres.

There are similar bikes available for less money, but if you have your heart set on a Specialized Tarmac SL8, this model offers more performance than most will ever need.

Just factor in enough extra cash to replace the brake rotors if you live anywhere where it rains regularly.

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