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Specialized Tarmac vs Roubaix: The best Specialized road bike for you in 2024
The Specialized Tarmac and Roubaix are, along with the lightweight Aethos, the giant American brand’s carbon fibre road bikes. Both the Tarmac and Roubaix had a makeover in 2023, with the latest upgrades designated SL8.
They’re both available in a range of specs, with the top spec S-Works models priced the same for both. The Roubaix range is deeper, with a lower-priced entry-level model, while unlike the Roubaix, the Tarmac offers both Shimano and SRAM options in its higher-priced bikes.
While the Tarmac is an all-out race bike, the Roubaix is endurance-oriented, with a range of features to add ride comfort and a more stability-focussed geometry. The latest Roubaix stretches into the all-road category, allowing you to head onto light gravel too. Here, we’ll compare the features of the Specialized Tarmac and Roubaix bikes, then lay out all the specs offered in the UK for each, finally providing some advice on how to choose between the two.
Specialized Tarmac SL8 vs Roubaix SL8: Key features at a glance
Specialized Tarmac SL8
- Pure race bike
- Aggressive geometry
- Aero tube profiles
- Integrated cables
- 32mm tyre clearance
Specialized Roubaix SL8
- Endurance geometry
- Future Shock suspension headset
- External cable routing
- Mudguard, top tube bag and third bottle cage mounts
- 40mm tyre clearance
Specialized Tarmac vs Roubaix: comfort and weight
The Specialized Tarmac SL8 has been designed to increase ride comfort, when compared to its predecessor, without sacrificing performance. The change has largely been achieved by designing a slimmer seat tube and seatpost relative to the Tarmac SL7. That’s allowed Specialized to reduce bike weight, so that top spec S-Works bikes have a claimed weight below the UCI 6.8kg weight limit, although once pedals and bottle cages are added, they sit right on 6.8kg.
In contrast, the Roubaix prioritises comfort over low weight, so the top spec bike cedes a couple of hundred grams to the Tarmac at 7.2kg.
That’s in large part due to the Roubaix’s more complex Future Shock headset system, which provides up to 20mm of vertical travel to help smooth the road. It includes a spring between the top of the head tube and the stem, which deforms to absorb road vibrations and also helps keep the tyre in greater contact with the road surface.
There are three grades of Future Shock. The highest spec bikes are equipped with a Future Shock 3.3 headset. This is hydraulically damped to control vertical displacement. There are three spring options to suit the rider and the road surface. You can also add pre-load washers and alter the setting from the headset cap while riding.
Next down is the Future Shock 3.2. This has similar hydraulic damping and pre-load adjustment, but can’t be tuned while riding.
Finally, the lower Roubaix specs have a Future Shock 3.1 design, which is undamped but can still be adjusted at home.
There’s a comfort-enhancing design at the rear of the Roubaix too, called After Shock, where the seatpost clamp is moved down the seat tube to offer 20mm of fore and aft flex.
Specialized Tarmac vs Roubaix: aerodynamics
The Tarmac SL8’s aerodynamics have been improved by a claimed 16.6 seconds over 40km at 45kmh from its predecessor Tarmac SL7. That’s in part due to the ‘Speed Sniffer’ forward protrusion on the head tube, resulting in a deeper profile that’s claimed to improve airflow.
The newer bike’s narrower seat tube is also claimed to make it faster, as well as aiding comfort, while the S-Works Tarmac SL8 has a one-piece Roval Rapide Cockpit bar/stem rather than the SL7’s separate bar and stem.
The Roubaix, meanwhile, is not designed around aero as much as compliance, although it is still claimed to be 11 seconds faster over 100km than its predecessor. The Future Shock head tube prevents integrated cabling, so the bike is unusual among high spec modern road bikes in still having external cables – or rather hoses – that run into the down tube. But the head tube itself is now more aero and the seatpost has a truncated kamm-tail section.
Specialized Tarmac vs Roubaix: geometry
As you’d expect, the race-oriented Tarmac is more aggressive than the endurance-focussed Roubaix.
That’s reflected in the size 56 Tarmac frame’s 565mm stack and 395mm reach, as against the Roubaix’s 605mm and 389mm. The Roubaix’s 73 degree head tube angle is half a degree slacker than the Tarmac, although its head tube is actually shorter by 17mm to accommodate the Future Shock system.
The Roubaix’s bottom bracket drop at 78mm is 6mm greater than the Tarmac’s, its 420mm chainstays are 10mm longer than the Tarmac’s and its 1012mm wheelbase is longer than the Tarmac’s 991mm by 21mm.
All the above indicate the Roubaix’s emphasis on stability rather than the Tarmac’s more racy ride. Its 40mm tyre clearance provides the space to set it up for all-road riding, while the Tarmac SL8’s 32mm clearance confines it principally to metalled roads, although it’s not averse to a little gravel or the cobbles when raced by the pros.
For the first time, the latest iteration of the Roubaix has mudguard fittings, a useful addition to an endurance bike. You don’t get them with the Tarmac though, but maybe you’ll be saving your Tarmac for best?
Specialized Tarmac vs Roubaix: frame grades
As is common among bike brands, Specialized sells its road bikes with the same frame geometry but made in different grades of carbon fibre.
Both the Tarmac and the Roubaix are available at S-Works level with the highest grade FACT 12r carbon fibre, which lowers weight. In the case of the Tarmac SL8, there’s a 280g claimed frame weight advantage for the FACT 12r frame over the FACT 10r frame, with the former weighing 1.37kg in size 56.
The Roubaix is only available made in FACT 12r and FACT 10r carbon. The Tarmac SL8 also has these two grades, plus it adds a third FACT 9r carbon grade in the older SL7 frameset.
Specialized Tarmac vs Roubaix: sizing
There’s a good range of sizes for both the Tarmac and the Roubaix, with both bikes offering seven frame sizes: 44cm, 49cm, 52cm, 54cm, 56cm, 58cm and 61cm, so shorter and taller riders are well catered for.
For some specs, the full range of sizes may not be available in all colours though.
Specialized Tarmac SL8 vs Roubaix SL8: groupsets
Specialized sells the Tarmac SL8 with a choice of either SRAM or Shimano groupsets, with similar pricing for each at the Red AXS/Dura-Ace and Ultegra/Force levels. The lowest priced Expert build on the Tarmac SL8 frame is fitted with SRAM Rival. All the above are equipped with a power meter, either from SRAM or 4iiii.
There are also Shimano 105 Di2 and mechanical 105 options for the Tarmac, although these are on the older SL7 platform rather than the SL8 and are not equipped with a power meter.
In contrast, higher spec Roubaix bikes are all equipped with SRAM groupsets with a power meter. It’s only the lowest two specs that have Shimano groupsets, either 105 12-speed mechanical or Tiagra 10-speed, and omit the power meter.
Specialized Tarmac vs Roubaix: wheels and tyres
While the Tarmac has road-focussed wheelsets, the Roubaix’s wheels are more all-road oriented.
The S-Works Tarmac SL8, for example, is fitted with 51mm front/60mm rear depth Roval Rapide CLX II wheels with a claimed weight of 1,520g and a width of 35mm external and 21mm internal. The S-Works Roubaix has Roval Terra CLX II wheels, which are lighter at 1,250g and wider with a 25mm internal width, but shallower at 32mm deep. Both wheelsets retail for the same £2,500 price if bought separately.
That difference in wheel dimensions is reflected in the fitted tyres: 26mm on the Tarmac and 32mm in the Roubaix.
Further down the price levels, in both the Tarmac and the Roubaix there are lower spec carbon wheels, before the lowest priced bikes swap to alloy wheelsets.
A note on the Specialized Allez range
Sitting below Specialized’s carbon bikes, the Allez is its entry-level alloy road bike. The latest Allez, launched in 2023, isn’t quite as entry-level as the previous bike. It now includes disc brakes and tyre clearance has been increased, so that although the Allez comes equipped with 30mm tyres, you can increase that to 35mm.
While Specialized’s higher spec bike models are, well, specialised for racing, endurance or, in the case of the Aethos, low weight, the Allez aims to be much more of an all-rounder. The Allez range does include the racier Allez Sprint though, a favourite for criterium racers.
Specialized Tarmac vs Roubaix: ranges compared
Next, we’ll run through the entire ranges for each of Specialized’s road bikes, from the most expensive to the entry spec for each, with a brief spec run-down.
While the Tarmac is available with the older SL7 frame on lower spec bikes, as well as the newer SL8, the Roubaix is only available as the latest SL8 variant. Both bikes offer a frameset-only option as well as full builds.
Specialized Tarmac bike range
S-Works Tarmac SL8 LTD
Toppling the Dura-Ace spec as the most expensive Tarmac SL8, the LTD spec is kitted out with the second generation SRAM Red AXS groupset and the same Roval wheels as the Dura-Ace bike. You do get a Hammerhead computer thrown in.
- Frame/fork: S-Works Tarmac SL8 FACT 12r
- Handlebars: Roval Rapide Cockpit one-piece
- Groupset: SRAM Red AXS 48/35, 10-33t 12-speed
- Power meter: SRAM Red AXS double sided
- Wheels: Roval Rapide CLX II
- Saddle: S-Works Power with Mirror
- Claimed weight: 6.78kg, size 56
- Price: £12,500
S-Works Tarmac SL8 Shimano Dura-Ace Di2
The Dura-Ace spec has a pro-level build with a mid-compact 52/36t crankset and a 4iiii power meter rather than the in-series Shimano one. There’s a slightly less flashy S-Works saddle without a 3D printed Mirror top.
- Frame/fork: S-Works Tarmac SL8 FACT 12r
- Handlebars: Roval Rapide Cockpit one-piece
- Groupset: Shimano Dura-Ace Di2 52/36, 11-30t 12-speed
- Power meter: 4iiii Precision 3 Pro double sided
- Wheels: Roval Rapide CLX II
- Saddle: BG S-Works Power
- Claimed weight: 6.62kg, size 56
- Price: £12,000
S-Works Tarmac SL8 SRAM Red AXS
As well as the LTD spec, you can also buy the S-Works Tarmac SL8 with the second generation SRAM Red AXS groupset and the same Roval wheels and Mirror saddle but without a computer at a slightly lower price.
You can still buy the bike equipped with ‘old’ SRAM Red in some sizes at the same £12,000 price.
- Frame/fork: S-Works Tarmac SL8 FACT 12r
- Handlebars: Roval Rapide Cockpit one-piece
- Groupset: SRAM Red AXS 48/35, 10-33t 12-speed
- Power meter: SRAM Red AXS double sided
- Wheels: Roval Rapide CLX II
- Saddle: S-Works Power with Mirror
- Claimed weight: 6.66kg, size 56
- Price: £12,000
Specialized Tarmac SL8 Pro Ultegra Di2
Move down to the Pro spec Tarmacs and the frame and fork grade drops from FACT 12r to FACT 10r. Other changes include a two-piece bar and stem and a wheel change, while the 4iiii power meter is single sided.
- Frame/fork: Tarmac SL8 FACT 10r
- Handlebars: Roval Rapide carbon on Tarmac integrated stem
- Groupset: Shimano Ultegra Di2 52/36, 11-30t 12-speed
- Power meter: 4iiii Precision 3 single sided
- Wheels: Roval Rapide CL II
- Saddle: BG Power Pro
- Claimed weight: 7.16kg, size 56
- Price: £8,000
Specialized Tarmac SL8 Pro SRAM Force AXS
The same Pro level bike is also available equipped with SRAM Force AXS. There’s a 280g claimed weight increase, although you do get a double-sided in-series SRAM Force power meter.
- Frame/fork: Tarmac SL8 FACT 10r
- Handlebars: Roval Rapide carbon on Tarmac integrated stem
- Groupset: SRAM Force AXS 48/35, 10-33t 12-speed
- Power meter: SRAM Force double sided
- Wheels: Roval Rapide CL II
- Saddle: BG Power Pro
- Claimed weight: 7.44kg, size 56
- Price: £8,000
Specialized Tarmac SL8 Expert
The final Tarmac SL8 bike spec is the Expert. This has the same frame as the Pro, but swaps to alloy bars and a lower spec Power saddle. The SRAM Rival groupset adds more range, with a 10-36t cassette replacing the 10-33t on the Pro. It includes the Rival single-sided power meter. The Roval C38 wheelset is still carbon rather than alloy.
- Frame/fork: Tarmac SL8 FACT 10r
- Handlebars: Specialized Expert Shallow Drop alloy on Tarmac integrated stem
- Groupset: SRAM Rival AXS 48/35, 10-36t 12-speed
- Power meter: SRAM Rival single sided
- Wheels: Roval C38 carbon
- Saddle: BG Power Expert
- Claimed weight: 7.77kg, size 56
- Price: £6,000
Specialized Tarmac SL7 Comp
Lower priced Tarmac bikes swap to the SL7 frame, which was originally launched in 2021, and FACT 9r carbon fibre. There are corresponding spec drops for the wheels and other components.
- Frame/fork: Tarmac FACT 9r
- Handlebars: Specialized Shallow Drop alloy on Tarmac integrated stem
- Groupset: Shimano 105 Di2 52/36, 11-34t 12-speed
- Power meter: None
- Wheels: DT Swiss R470 alloy
- Saddle: BG Power Sport
- Claimed weight: 8.10kg, size 56
- Price: £4,250
Specialized Tarmac SL7 Sport
The entry-level Tarmac is the SL7 frameset and is equipped with mechanical Shimano 105. It’s the only Tarmac without electronic shifting, but otherwise shares its spec with the Tarmac SL7 Comp above.
- Frame/fork: Tarmac FACT 9r
- Handlebars: Specialized Shallow Drop alloy on Tarmac integrated stem
- Groupset: Shimano 105 52/36, 11-34t 12-speed
- Power meter: None
- Wheels: DT Swiss R470 alloy
- Saddle: BG Power Sport
- Claimed weight: 8.10kg, size 56
- Price: £3,250
Specialized Tarmac SL8 frameset
You can buy the S-Works Tarmac SL8 as a FACT 12r carbon frameset in a range of colours, priced at £4,750 and with a claimed 1.41kg weight for a size 56 or unpainted, when the claimed weight drops to 1.37kg.
There’s also a FACT 10r frameset available, priced at £3,500 and with a claimed weight of 1.69kg for a size 56.
Specialized Roubaix SL8 bike range
While Specialized sells the Tarmac with both the SL8 and the older SL7 frame design, the Roubaix is only available with the latest SL8 frameset. The Roubaix specs are also SRAM-heavy, with only the lower spec bikes equipped with Shimano groupsets, 105 and Tiagra mechanical.
S-Works Roubaix SL8 SRAM Red AXS
The top spec of the Roubaix is equipped with the latest SRAM Red AXS groupset – there’s no Dura-Ace option. While the S-Works Tarmac SL8 has the 48/35t crankset with a 10-33t cassette, the Roubaix SL8 has the less racy 46/33t crankset with the wider range 10-36t cassette. Tyres are also wider at 32mm rather than the Tarmac’s 26mm.
As with the Tarmac, you can still buy the bike equipped with ‘old’ SRAM Red in some sizes at the same £12,000 price.
- Frame/fork: S-Works Roubaix SL8 FACT 12r
- Handlebars: S-Works Carbon Hover carbon on S-Works Future Stem and Future Shock 3.3 headset
- Groupset: SRAM Red AXS 46/33, 10-36t 12-speed
- Power meter: SRAM Red AXS double sided
- Wheels: Roval Terra CLX II
- Saddle: S-Works Power with Mirror
- Claimed weight: 7.20kg, size 56
- Price: £12,000
Specialized Roubaix SL8 Pro
The frame of the Pro level bike takes a step down to FACT 10r carbon from FACT 12r. The Future Shock suspension stem remains the same as on the S-Works bike. It’s equipped with SRAM Force AXS with the in-series double sided power meter.
- Frame/fork: Roubaix SL8 FACT 10r
- Handlebars: S-Works Carbon Hover carbon on Future Stem Pro and Future Shock 3.3 headset
- Groupset: SRAM Force AXS 46/33, 10-36t 12-speed
- Power meter: SRAM Force double sided
- Wheels: Roval Terra CL II
- Saddle: BG Power Pro
- Claimed weight: 8.10kg, size 56
- Price: £8,000
Specialized Roubaix SL8 Expert
The Expert spec uses the same frame as the Pro, but with the Future Shock 3.2 headset rather than the 3.3. The groupset is SRAM Rival, with a single sided power meter.
- Frame/fork: Roubaix SL8 FACT 10r
- Handlebars: Specialized Hover Expert alloy on Future Stem Pro and Future Shock 3.2 headset
- Groupset: SRAM Rival AXS 46/33, 10-36t 12-speed
- Power meter: SRAM Rival single sided
- Wheels: Roval Terra C carbon
- Saddle: BG Power Expert
- Claimed weight: 8.62kg, size 56
- Price: £6,000
Specialized Roubaix SL8 Comp
The Comp spec has mechanical Shimano 105 with a compact crankset and alloy wheels in place of carbon.
- Frame/fork: Roubaix SL8 FACT 10r
- Handlebars: Specialized Hover Comp alloy on Future Stem Comp and Future Shock 3.2 headset
- Groupset: Shimano 105 50/34, 11-36t 12-speed
- Power meter: None
- Wheels: DT Swiss G540 alloy
- Saddle: BG Power Sport
- Claimed weight: 8.97kg, size 56
- Price: £5,000
Specialized Roubaix SL8 Sport Apex
Specialized offers a SRAM Apex AXS electronic single ring groupset option on the Sport, in addition to the 105 spec below, giving you the option of electronic or mechanical shifting at this level. The headset suspension system is the Future Shock 3.1 in place of 3.2.
- Frame/fork: Roubaix SL8 FACT 10r
- Handlebars: Specialized Hover Comp alloy on Future Stem Comp and Future Shock 3.1 headset
- Groupset: SRAM Apex AXS 42, 11-44t 12-speed
- Power meter: SRAM Rival single sided
- Wheels: DT Swiss G540 alloy
- Saddle: BG Power Sport
- Claimed weight: 8.93kg, size 56
- Price: £3,250
Specialized Roubaix SL8 Sport 105
The Roubaix Sport is also available equipped with Shimano 105, in an otherwise similar spec.
- Frame/fork: Roubaix SL8 FACT 10r
- Handlebars: Specialized Hover Comp alloy on Future Stem Comp and Future Shock 3.1 headset
- Groupset: Shimano 105 50/34, 11-36t 12-speed
- Power meter: None
- Wheels: DT Swiss G540 alloy
- Saddle: BG Power Sport
- Claimed weight: 9.07kg, size 56
- Price: £3,000
Specialized Roubaix SL8
While all the above bikes are 12-speed, the entry-level Roubaix SL8 has a 10-speed Shimano Tiagra groupset. The gear spread is also slightly lower than the 105 spec, with an 11-34t cassette replacing the 11-36t and the wheels are in-house Axis Elite rather than from DT Swiss.
- Frame/fork: Roubaix SL8 FACT 10r
- Handlebars: Specialized Hover Comp alloy on Future Stem Comp and Future Shock 3.1 headset
- Groupset: Shimano Tiagra 50/34, 11-34t 12-speed
- Power meter: None
- Wheels: Axis Elite alloy
- Saddle: BG Power Sport
- Claimed weight: 9.46kg, size 56
- Price: £2,500
S-Works Roubaix SL8 frameset
You can buy the S-Works Roubaix SL8 as a FACT 12r carbon frameset with a Future Shock 3.3 headset, priced at £4,750 and with a claimed 2.11kg weight. Whereas there’s a range of colours available for the Tarmac SL8 frameset, there’s only one colour option for the Roubaix.
Specialized Tarmac vs Roubaix: which should you choose?
There’s a clear difference in intent between the Specialized Tarmac and the Roubaix.
If you’re into racing and faster riding, you’re likely to prefer the Tarmac. It’s more aero, has faster handling and, let’s face it, looks more pro with its integrated cabling, even in its lower specs.
In contrast, the Roubaix’s more relaxed ride position, greater stability and comfort-enhancing design features are likely to appeal to riders who want to go longer, or who just appreciate a less all-in ride position. Its looks are a little old-fashioned now though, particularly due to its external cables.
With its 40mm tyre clearance, extra mounting points and suspension, the Roubaix is edging into all-road territory, so it’s also the better option if you like to mix in some light gravel with your road riding. The option to fit full length mudguards means that it’s also going to be nicer to ride when the weather takes a turn for the worse.
Read our full reviews of the S-Works Tarmac SL8 and Specialized Roubaix SL8 Expert for more info and our ride reports.
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