Specialized Tarmac SL8 Expert

The Specialized Tarmac SL8 Expert is built around a stunning frameset and quality components. Well, almost – the tyres are a bit naff on a bike of this quality, but change them out for something more befitting and you’ll have a package that rides brilliantly and delivers on stiffness and performance, and at a decent weight too.

Specialized SL8 Expert: Ride

When the S-Works version of the Tarmac SL8 was released back in 2023 Jamie described it in his review as ‘narrowing in on perfection – this is the new race bike benchmark’, and after spending a couple of months aboard this non-S-Works Expert model I can see why. Except for the tyres – they’re a bit ‘meh’.

Let’s address that straight away. The Expert comes with a pair of S-Works Turbo tyres in a 26mm width fitted to some Roval C38 carbon wheels, and on my first ride I could feel some conflict between the ride quality of the frameset and the feeling from the tyres. The SL8 was noticeably comfortable, but there was a sense of harshness and deadness to the ride from the part of the bike furthest away from me.

I could tell it was from the tyres; they had a budget, not very supple feel to them, so on my next ride I fitted my current go-to aero wheels (Scribe’s Core Superlight 60-D) with a pair of 28mm Michelin Pro 5s, and the overall ride was instantly transformed.

Using the deep-section wheels also highlighted that no matter how aero the SL8 is claimed to be (and how much more aero it is than the SL7 was), it’s rim depth that gives the notable, real-world benefits.

Anyway, back to the tyres…

Swapping those Michelin Pro 5s onto the Specialized wheels from the Turbos and inflating them to a like-for-like pressure made the SL8 Expert finally feel like a complete package. Now I could finally feel the full extent of the quality of the SL8’s frameset, and what an awesome-feeling setup it is.

For a high-performance road bike it has an incredibly smooth ride feel, and it’s very ‘talkative’ in terms of feedback. It is, as you’d expect, stiff where it needs to be and compliant in other places, but it’s the transition between the two where the biggest benefits are felt. The carbon layup has obviously been well designed and Specialized’s designers haven’t focused on all-out performance to the detriment of comfort.

The SL8 is efficient by its design, and made even more so by being a very pleasant place to be. I could ride this bike flat out for a long time without getting battered about from road imperfections and vibrations.

At 7.2kg on our scales the Expert isn’t going to bother the UCI, but it is still real-world light, which means it’s responsive, whether from a standing start or accelerating when rolling, and is certainly no slouch on the climbs.

In fact, I didn’t really find anywhere the SL8 Expert wasn’t impressive. I used it for commuting occasionally and the quick handling which plays a blinder on technical descents wasn’t tricky to deal with when filtering through traffic in the city.

Review bikes often come with more spacers than necessary so that they can fit multiple riders as they do the circuit, as the Expert has here. I’d probably knock 20mm off the height if it was my own bike, but set up like this, I could ride it for longer, steadier rides without issue.

From a ride point of view, I really can’t fault the quality or behaviour of the SL8. For a race bike, it’s got the ability to be a bit of an all-rounder without sacrificing any speed or performance.

Specialized SL8 Expert: Frame & fork

Specialized’s carbon fibre framesets are given number grades. They mean little in comparison to other frames on the market, but generally the higher the number (followed by an R), the higher up the pecking order it is in Specialized’s line-up.

For clarity, the top-of-the-range S-Works models use 12R, while this Expert version uses 10R. What that means is this frame is about 100g heavier than the S-Works model, but it’s still light at sub-800g.

For the SL7 and the SL8 Specialized has focused on aerodynamics to create what it considers a great all-rounder. In fact, it dropped the Venge from the line-up quite a few years back, as an aero bike was no longer needed in the catalogue.

The SL8 has a new aero head tube/nose cone which Specialized calls the Speed Sniffer – it says it means this frame would be 16.6 seconds faster over 40km than an identically equipped SL7 under the same conditions.

With the 38mm wheels fitted as standard to this Expert model it’s a quick bike, but I wouldn’t say it feels especially slippery. In the real world it’s not noticeably faster than my 2022 Giant TCR, for instance – so all of this is very marginal.

We’re not done with the stats yet either. Spesh says that the SL8 delivers a 33% improvement in terms of stiffness to weight versus the SL7, while being 6% smoother in the saddle.

As I said above, this is a light, stiff, comfortable and efficient bike, so while I can’t verify the numbers, it’s certainly an impressive bit of kit.

Keeping the aero theme, Specialized has run the brake hoses fully internally, and any wires for the gearing system are also hidden away.

The seat tube is aero shaped with a slight cutout for the rear wheel, and the seatpost clamp design is smooth and largely internal too.

There are three bottle cage bosses on the down tube to give a little bit of adjustment on where to position your bottle, while the seat tube has the standard two.

You also get a choice of three colours for the Expert. This Satin Champagne/Black Pearl is rather striking in the sun, while the other options are Gloss White/Black Metallic or Gloss Deep Lake Metallic/Green Pearl Over Seafoam – which is a long-winded way of saying blue, but it also looks good in my eyes.

Specialized has gone with a BSA threaded bottom bracket system, and has allowed for 32mm tyres.

It says there can be more differences between two people of the same gender than between two riders of differing genders, so it doesn’t make gender-specific bikes.

Specialized SL8 Expert: Geometry

The SL8 is available in seven sizes ranging from a 44 to a 61 to cover pretty much anyone who rides a bike, I would have thought.

The smallest two bikes (44 and 49) come with 165mm cranks, which is good to see as many brands don’t go below 170mm. The larger sizes get 170/172.5/175mm depending on frame size. The 56 has 172.5cm cranks.

Stem lengths and handlebar widths are determined according to size, too, with the 44 getting a 70mm stem and a 360mm handlebar, for instance, while the 61 gets a 110mm stem and 44cm handlebar. I generally get on fine with off-the-shelf builds’ component sizing, but if you don’t you might need to factor in replacing some things.

The 56 I’m riding here uses a 100mm stem and 42cm handlebar.

The frame has a head tube length of 157mm, top tube (horizontal) of 563mm, and a seat tube of 494mm. Specialized gives stack and reach figures measured to the stem to include the bearing top cap, which come out as 573mm and 393mm respectively.

The wheelbase is 991mm, which is what gives the SL8 its nimble, flickable feel, and the fork has an offset of 44mm.

Angles-wise, we’re looking at 73.5 degrees for both the seat tube and head tube.

Specialized SL8 Expert: Groupset

As I mentioned earlier, the SL8 comes in two frame designs, the FACT 10R or the FACT 12R S-Works. The latter costs £12k with either Shimano Dura-Ace Di2 or SRAM Red AXS, and if you have a little more cash burning a hole in your pocket and you want a bike to ‘give you wiiiiiiings’ then the Red Bull 2025 TdF build is a cool £13,499!

Of the FACT 10R-framed bikes, the SL8 Pro is £8,250 with Shimano Ultegra Di2 or SRAM Force AXS, and has a one-piece carbon cockpit and deep-section wheels, while the SL8 Expert sits below it, with a SRAM Rival AXS build for £5,500 or the Shimano Ultegra Di2 option that we have here for £6,000.

Ultegra Di2 R8170 needs no introduction as it has been out a few years now (or you can read our review if you aren’t up to speed), but to sum things up: the shifting is now very light, very precise and has exceptional battery life.

Specialized has gone with a 52/36-tooth chainset and a 12-speed 11-30T cassette here, which gives an overall gear range of something befitting a performance road bike of this ilk.

For the braking there’s a 160mm rotor at the front and a 140mm at the rear, which is spot on from my point of view, giving loads of braking power mated to Ultegra’s impressive feel and modulation at the levers.

Specialized hasn’t deviated from the group either, to save a bit of cash, with an Ultegra chain used and a Shimano bottom bracket.

Specialized SL8 Expert: Finishing kit

Cockpit-wise, the Expert has a two-piece setup incorporating a Tarmac integrated stem sitting at 6 degrees and an Expert Shallow Drop alloy handlebar. I’m rather surprised not to see a carbon bar, considering the £6k price point, but this one is comfortable and does a good job all round.

It’s wrapped in Supacaz’s Super Sticky Kush bar tape, which is one of my faves.

The seatpost is carbon – Specialized’s S-Works model, which has a 15mm offset, and on top is a Body Geometry Power Expert saddle which I found comfortable. I get on well with all of Specialized’s saddles, so no surprise there.

Specialized SL8 Expert: Wheels & tyres

Roval is Specialized’s in-house wheel brand, and the C38s here have a 38mm-deep carbon rim with a 21mm internal width and can be set up to run tubeless.

It’s a good general set of wheels for all kinds of riding, as long as aerodynamics and speed aren’t your main goal. The performance is decent, though, as is the weight, and the quality seems to be very high. I had no issues with any out-of-true shenanigans and the hubs ran smoothly throughout the review period. Lateral stiffness is also good, with no flex rearing its head.

Specialized supplies the bike with its Turbo Ultralight inner tubes and those S-Works Turbo tyres I talked about earlier. The grip is above average but the ride quality is poor, and they aren’t the quickest rolling either.

Swap them the first chance you get, especially if it’s the summer, and treat yourself to something befitting a bike of this calibre. I’m not talking super high end either – the Michelins I used are about £60 a tyre at RRP.

Specialized SL8 Expert: Value

How does the SL8 Expert compare with the competition?

Earlier in the year I rode the Scott Addict RC Pro and thought it was amazing, describing it as a showcase of what’s achievable in road bike design in terms of weight, performance and quality. This Shimano Dura-Ace Di2-equipped model, with its £8,599 price tag, weighed just 6.58kg on our scales!

It’s not Scott’s aero bike – that’s left to the Foil – but real-world conditions meant it was fast and efficient pretty much everywhere, so similar to the SL8.

The Addict RC 20 uses the same RC HMX frame and fork of the Pro model but with an Ultegra Di2 groupset, 40mm-deep carbon wheels, and a mix of carbon and alloy components, coming in cheaper at £5,899.

The Addict Pro has the slightly better all-round ride feel, but we are talking the marginalist of margins here, and I would be hard pushed to choose between the Scott and Specialized.

Giant also has an aero bike and a lightweight race bike, rather than amalgamating them like Specialized has, but I’d choose the latter, the TCR, as a comparison to the SL8. At £6,499 the Ultegra Di2-equipped version of the TCR Advanced Pro 0 model Mat tested and was impressed with last year is a bit pricier than the SL8 Expert, although it comes with a similar build, including 40mm-deep own-brand carbon wheels.

Aaron was also impressed with the Reacto 9000, Merida’s aero road bike. It’s heavier than the Specialized by around 400g but you are getting larger section tubing and a set of 60mm-deep carbon wheels. It’s an impressive build for £6,250 with those wheels and the full-carbon cockpit, both from Vision.

If you are looking for something a step to the side from the big mainstream brands then I’d highly recommend the A1R0evo, an aero road bike from UK brand Handsling, with a frameset created from its own moulds. I was massively impressed by the way it rode, and it is priced very competitively too. An Ultegra Di2 build with full-carbon one-piece cockpit, Parcours Alta 36mm carbon wheels and Schwalbe One tyres will set you back ‘just’ £5,599.99.

For more options, check out our guides to the best road bikes and the best aero road bikes.

Specialized SL8 Expert: Conclusion

So, should you consider the SL8? Yes, definitely. There is a lot of very good quality competition at this price point, but the SL8 does have an excellent frameset and an exceptional ride quality once you ditch the standard tyres, so it definitely gets my recommendation.

Verdict

Stunning frameset and ride quality, hampered by the tyre choice

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