What is the ultimate road superbike in 2023? Specialized S-Works Tarmac SL8 vs Cannondale SuperSix EVO LAB71

If you had an unlimited amount of money, the desire to go as fast as possible and the necessary will and flexibility to copy the pros, what bike would you get? Two likely candidates are the new range-topping Specialized S-Works Tarmac SL8 and Cannondale LAB71 Supersix Evo 4, but what are the differences and which one would we have? Let's find out!

> Is Aaron's new Cannondale Supersix Evo LAB71 the nicest bike in the office?

If you’re Aaron, then the answer to that question is the fourth-generation Cannondale SuperSix Evo, the top-of-the-range Lab71 model in fact. It's certainly a very nice bike, and you can check out his full custom build using the link above. However, did Aaron jump the gun, and should he have waited for the release of the latest Tarmac SL8? It certainly boasts a boatload of impressive figures.

In many ways, both the Lab71 Supersix and SL8 Tarmac are very similar. They’re both designed to be very light, they’ve both got big aero claims, they’re both horrendously expensive, they even look quite similar… and we reckon they represent the very pinnacle in do-it-all race bikes. 

Which one is preferable? Well, first we’re going to compare the weights, the aero claims, the builds, the geometry, the prices and the ride quality, before trying to choose a favourite... 

5 things that are similar

• Both bikes have BSA threaded bottom brackets
• Both top-of-the-range bikes come with one-piece cockpits
• Both bikes are disc brake only
• Both of the bikes are currently being used in the World Tour peloton
• Both bikes ship with own-brand components (wheels/bar/seatpost)

5 differences

• The SuperSix has 30mm tyre clearance vs 32mm on the SL8
• The steerer tube on the Cannondale is D-shaped
• The Di2 battery is accessed from the BB on the SuperSix, and the seatpost on the SL8
• Specialized-sponsored teams only use the SL8, whereas Cannondale riders also have the option of the SystemSix aero bike.
• The thru-axle end is covered on the Cannondale

Weight

> The lightest road bike frames and components in the world

Let’s kick off with weight, as despite my belief that it’s a secondary factor in any bike purchasing decision (other than hill climb bikes) both brands have made quite a lot of noise about their gram savings.

The Cannondale LAB71 Series 0 carbon layup uses a special fibre and nano-resin composite to shed 40 grams over the Himod version of the SuperSix frame, resulting in a weight of 770g for a painted 56cm frameset. As such, a fully built Lab71 will tip the scales at the UCI minimum weight limit of 6.8kg. That’s some 500g lighter than the SuperSix Evo 3.

As impressive as that is, it's an area where the SL8 can do one better. An S-Works frame like the one we've been riding weighs in at just 680g for a 56cm frame in its lightest colourways. The Ghost White Pearl version I've been riding is approximately 730g.

> Lightweight v aero: which is best?

Obviously, an entire bike is more useful. Aaron's full build without pedals is 6.9kg with SRAM Red AXS and lightweight Zipp 353 NSW wheels, the same as the SL8 in it's current setup with deeper Roval Rapide CLX II wheels and butyl inner tubes.

It's safe to say that either bike is well capable of tickling the UCI weight limit, but if you're looking for the lightest out of the box then a Dura Ace S-Works SL8 has a claimed weight of 6.6kg.

Round 1: Specialized Tarmac SL8

Builds and prices

It is worth noting that while we’ve both got the top-of-the-range models here, both Specialized and Cannondale do offer the SL8 and SuperSix respectively at lower price points (slightly lower, that is). Neither are going to break any records for being light on the wallet, though. 

> Best road bikes under £2000

The Tarmac range is pretty simple. You’ve got two frame tiers, S-Works being the higher one and the Fact 10R frame (780 grams) being the second. Then you’ve got three models: the S-Works with either Dura-Ace or SRAM Red AXS at the top, the SL8 Pro with Ultegra or Force AXS, and the Expert with shallower wheels and SRAM Rival AXS.

The SuperSix, meanwhile, is split into three frame tiers: the LAB71 sits at the top of the tree, then you’ve got the Hi-Mod which adds 40 grams for an 810g frame weight, and finally the regular SuperSix Evo with a weight of 930 grams.

> Cannondale launches new aero-optimised SuperSix Evo 4

Once again, there are multiple builds of each: the Lab71 with Shimano Dura-Ace, the Hi-Mod with either SRAM Red AXS or Ultegra Di2, and the regular Evo with SRAM Force AXS, Shimano Ultegra Di2 or the cheapest with Shimano 105 Di2.

As far as pricing is concerned, well it depends on which tier you want really! The S-Works and LAB71 frames both cost £4,750, but the Hi-Mod Supersix frameset is £3,750 whereas the SL8 is £3,000. From a frameset point of view, the Tarmac SL8 is the cheaper of the two.

If you wanted to purchase the top-tier complete bikes, then the S-Works SL8 at £12,000 comes in £500 cheaper than the Dura-Ace LAB71 Supersix. With the SL8, you also benefit from the choice of either SRAM or Shimano. Of course, you could always build up a frameset with whichever components you wish.

That’s where the good news for the Tarmac ends, though. In full bike builds the latest SuperSix offers a far lower price of entry with the Evo 3 (105 Di2 is shown above) starting at £4,000 compared to £6,000 for the Expert Tarmac with SRAM Rival AXS (albeit that is a higher spec build with carbon wheels). 

> 8 things you didn't know about the new Specialized Tarmac SL8

From a price to performance point of view, the ones to go for in our eyes would be the Fact 10R Specialized Tarmac Pro with Roval Rapide wheels and either 12-speed Force AXS or Ultegra Di2 (shown above) which is £8,000, or the Cannondale Supersix Evo 1 for £6,250.

Round 2: draw

Aero/speed

Without a wind tunnel, it's rather hard to quantify the speed of both bikes, but they certainly do feel fast. Both Aaron and I have put in plenty of miles on both bikes to be confident that they're some of the fastest out there - however, trying to determine which bike is faster in the real world is like trying to split hairs, and there are certainly only a few watts in it if any at all.

The SL8 is claimed to be 8 watts faster than the SL7 Tarmac thanks to a slimmer seat post and seat tube, 'Speed Sniffer' head tube and integrated bar and stem. The Cannondale engineers are keen to point out that despite being a lot lighter than the SystemSix out-and-out aero bike, the SuperSix with deep wheels comes very close to beating it in terms of drag figures.

> Has aero gone too far? 

If the rumours on forums combined with manufacturer claims are to be believed, then the SL8 could be around two watts faster than the SuperSix at 45kph - but we have no way of validating these figures and, to be honest, even if we could it's unlikely that such a difference could be concrete given margins of error in testing. 

On the road, Aaron and I are happy to admit that neither bike gave us an aero advantage and that clothing choice, wheel choice and body position are exponentially more important than trying to determine a minuscule difference in drag between the frames.

Round 3: draw

Geometry

> Should I buy a race bike or an endurance bike?

As we mentioned earlier, the two bikes are designed for racing, and as such they are both pretty aggressive machines. That means they’ve got low front ends - even with spacers - and plenty of reach so that you’re in as aero position as possible.

Both bikes are available in seven sizes from 44cm to 61cm, although there are a few minor differences at the smaller end of the scale.

Frame sizes

Specialized Tarmac SL8: 44, 49, 52, 54, 56, 58, 61

Cannondale Supersix Evo 4: 44, 48, 51, 54, 56, 58, 61

> How to read a bike geometry table

In terms of actual pure geometry, the two steeds are very similar as you might expect. We’ve plugged the 56cm bikes into geometry geeks to see what differences, if any, there might be, and if anything it's the Tarmac which is slightly more aggressive.

The reach and stack a little bit longer and lower on the Tarmac, but it really is marginal with only a tiny difference. The seat tube is shorter on the Tarmac, which leaves more exposed seatpost which, in turn, could contribute to greater rear-end compliance. The chainstay lengths, trail and seat tube angles are all but identical which results in bikes that handle very similarly.

Round 4: Specialized Tarmac SL8 (but only just)

Ride feel

The overriding sensation when riding both bikes back-to-back is that these really are do-it-all bikes. They both feel at home whether on the flats, the climbs, a perfectly surfaced race track or your less-than-perfect average UK road.

The bikes are of course integrated, but they're less hassle to live with than previous generations of aero bikes. For example, I owned the Venge ViAS which was very quick on the flat, but the extra weight and lack of maintainability ultimately were the reasons for its sale.

Secondly, compliance. It's a word that I dislike seeing in press releases because although it's very welcome even on race bikes, it does seem to be chucked around all too often. I maintain that you can tune the rear-end compliance of most modern bikes by opting for wider rims and tyres with lower pressures. That said, I'm thankful that bike development is now at a point where even the fastest bikes on the market can be ridden for six hours in relative, none-bone-shaking comfort.

The near-identical geometry results in bikes that handle very similarly. They both feel agile, sure-footed when descending and ready to race. That should come as little surprise, as it's a formula that has been used for the last several generations of these bikes. It's one that works.

As we mentioned previously, the aero gains/losses from the frames are minuscule, so I highly doubt that anyone could notice a few watts of difference out on the road. The weight is also very close. Even on a long mountain, 90g is nearly impossible to distinguish.

Round 5: draw

Which one would we choose?

It sounds like a cop out, but there is no clear winner here. To say that one of the bikes will help you beat your riding buddies over the other would be absurd.

As a feat of engineering, I have to say that the S-Works SL8 is, in my mind, the most impressive. How Specialized has reached the claimed aero levels, stiffness and compliance while producing a frame that is 90g lighter than Cannondale's best efforts is quite astonishing. Unfortunately for Specialized, in the real world this doesn't make the foggiest bit of difference.

In conclusion, if you do have the money and want to ride one of the latest and greatest super road race bikes. then either will serve you very well. Choose whichever one you prefer the aesthetics of, the paint job that excites you most or the brand you align to best.

Before buying either though, ask yourself: would an endurance bike suit me better? And do I really want to spend £6k more for one of these top-of-the-range models when 99% of the performance can be had for around half of that price?

PS: Aaron is keeping the SuperSix (no regrets, he says), while I will be sticking to my SL7. You can read why here. 

Which (if either) would you go for? Let us know in the comments section below and subscribe to the road.cc YouTube channel for lots more bike comparisons!