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Specialized Tarmac SL4 Sport review

2 Nov 2017

Great looking and responsive, the Tarmac SL4 Sport is a decent all-rounder with a competitive edge

Cyclist Rating: 

The 2018 Tarmac is Specialized’s ‘everything’ bike, aiming to be as compliant while climbing a mountain as it is on a Sunday group ride.

The SL4 Sport’s steering geometry and wheelbase are identical to the firm’s decidedly pricier higher-end Tarmacs, which have won the biggest races in the world under the likes of Peter Sagan.

This model represents the second rung on the nine-bike Tarmac ladder.


The Tarmac’s FACT carbon frameset contributes to an overall package just north of 8kg, which is not only respectable for this money, but also good enough to base an entire build or raft of upgrades around.

The bike’s oversized down tube and boxy (if sleekly finished) chainstays speak volumes about the Tarmac’s stiffness.

As does the squat 120mm head tube, which joins with the front of the down tube and curving top tube to create a tankard-sized expanse of carbon.

Given the low front end, there is potential to get Caleb Ewan-low over the bars should you fancy a sprint to the line.

Monocoque carbon forks enforce the feeling of stiffness and direct steering, while a steering geometry identical to Specialized’s race-winning S-Works Tarmac model provides an agile platform.

It’s also worth noting that the American firm’s quoted seat and head angles correlate almost exactly with our digital measurements – something of a rarity in our experience of most bike manufacturers.

Cabling is entirely internal, with inline adjusters for the front and rear mech in the cockpit area.

In brief, it doesn’t get the same complete overhaul as the higher-end Tarmacs for 2018, but for us is still a remarkably good platform for a keenly priced build.


The equipment adorning the Tarmac is largely from Shimano’s mid-range 105 groupset, famed for and proven in its affordable price, ease of use and long life.

There are 105 shifters/brake levers, front and rear derailleurs and 11-28 cassette. The chainset, however, is a Praxis 50/34 set-up, the conventional rim brake calipers are unspecified Axis units and the Specialized runs an 11-speed KMC chain.

Finishing kit

Specialized’s Body Geometry finishing kit is put to good use here, with 420mm alloy shallow-drop handlebars and a 90mm alloy stem providing exceptionally quick leverage for fast direction changes.

A 27.2mm carbon seatpost dials out road vibes while a Toupe Sport saddle is one of our all-time favourite places to sit for a long ride.


The DT Swiss R460 wheelset is a basic alloy set-up, and as you might expect, not the lightest.

However, they’re perfectly capable, and much better equipped for the changeable road surfaces of certainly most UK sportives, as they’ll roll with the knocks.

Featuring an 18mm internal diameter, they might be wearing 23c tyres on our test bikes, but can run anything up to 32c, for added cornering confidence and bump absorption.

Specialized’s own-brand Espoir tyres offer good puncture resistance, more than adequate grip and low rolling resistance – they’re a very good £30 tyre.

On the road

Speaking of Sagan, the ‘Sagan Superstar’ paintjob on this 2018-model SL4 Sport is the obvious first thing you fixate on when you meet this bike.

Deep black paint replete with metal flake finish, a gold Specialized head tube logo and down tube graphics are simply stunning.

Once we’re actually on the bike, the relative lack of weight is instantly noticeable and while compliance could be better, its responsiveness more than makes up for it. 

Even wearing what are effectively everyday training wheels, the Specialized is eager to respond to short, sharp accelerations on flat and rolling roads, and more than happy to gain altitude at pace, either with you seated or out of the saddle.

Once you do lever yourself off the exceptionally comfortable Toupe Sport seat, the stiffness of the frameset beneath you ensures there is absolutely no flex as you put the power down on a climb.

For unremarkable brakes, the Axis callipers do a good job of hauling the bike up on the descents; finessed modulation isn’t their forté, but they’re certainly able to stop you in short order.

Beyond the clear performance benefits of this bike, the way in which it quietly gets on with propelling you at speed makes it worthy of consideration for anyone with a stack of sportives booked for next spring.

Although its front end is solid, a simple upgrade to 25 or even 28c tyres (there’s frame clearance for it) would tone down the occasional jarring we did experience, and turn a great bike into a fantastic one.

The range of gears available here, with a smallest option of 34x28, and a largest of 50x11, is perfect for any terrain you’re likely to encounter on an organised ride, too.


We’re big fans of the Specialized Roubaix – it’s a very good option if you’re looking for a long-distance bike that’ll cover miles in comfort.

But while the Tarmac doesn’t feature its stablemate’s vibration-damping tech, it’s almost as cosy a place to be.

Plus – and it’s a big plus – it has the power to excite, thanks to a wheelbase that’s almost 2cm shorter, and more aggressive steering geometry.

Yes, the Tarmac can corner with the best of them, and with a much greater level of feedback than a lot of bikes at this price.

Downhill corners are carved through, and small adjustments to your line in sweeping turns is made easy by the leverage afforded by a 90mm stem.

This short stem can make it seem a little twitchy at times, but would easily be remedied by the fitment of a longer component, should it suit your body type.

We’d probably slap on a set of 25c tyres, too, for the extra cornering confidence they bring, and to dial out the final rough edges to road feedback.

However, it boils down to what you want from a sportive bike.

If you’re not made of money, and want something that’ll make you feel like Sagan, both the straight-line performance and cornering prowess of the Tarmac will make it worth your while.

Make no mistake, this is a bike that rewards commitment.


Frame: The Sagan Superstar paintjob is stunning. 8/10
Components: A good mix of 105 and Praxis components. 8/10 
Wheels: Basic but good enough for the job at hand. 8/10 
The Ride: Commitment is rewarded with performance. 8/10


Great looking and instantly responsive, the Tarmac SL4 Sport delivers decent all-round performance with a competitive edge.


Claimed Measured
Top Tube (TT) 537mm 535mm
Seat Tube (ST) 490mm 490mm
Down Tube (DT) N/A 615mm
Fork Length (FL) 368mm 368mm
Head Tube (HT) 120mm 120mm
Head Angle (HA) 73 72.9
Seat Angle (SA) 74 74
Wheelbase (WB) 970mm 972mm
BB drop (BB) 72mm 72mm


Specialized Tarmac SL4 Sport
Frame FACT 9r carbon frame, FACT carbon forks
Groupset Shimano 105
Brakes Axis
Chainset Praxis Alba M30, 50/34
Cassette Shimano 105, 11-28
Bars Specialized Shallow Drop, 6061 alloy
Stem Specialized, 3D forged alloy
Seatpost Specialized Comp, carbon
Wheels DT Swiss R460
Saddle Body Geometry Toupe Sport
Weight 8.10kg (size 52cm)

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