Specialized Tarmac SL8 - The World’s Best Race Bike

Specialized Tarmac SL8 - The World’s Best Race Bike

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It seems like only yesterday the Tarmac SL7 came out, replacing both the SL6 and the Venge in Specialized's lineup, creating both an aero and lightweight race bike in one fell swoop. Well, the new Tarmac SL8 trumps both of those bikes, furthering their redundancy and replacing them with one truly epic race-ready road bike.

The Tarmac SL8 takes some aero inspiration from the Venge, lightweight learnings from the Aethos, and combines them to create the world's fastest race bike. The development of the new Tarmac was a technical exercise in weight reduction, aerodynamics and improvements in frame stiffness and compliance, culminating in a bike that's the best of all worlds with massive performance gains. The SL8 is 15% lighter than the SL7, 33% improved stiffness-to-weight ratio, 6% smoother and 16.6s faster over 40km. Impressive stats.

Tarmac SL8

Race Winning Pedigree 

The Tarmac SL7 has been the most winning bike on the World Tour over the last four years and it's hard to improve on something like that, but the folks at Specialized are not ones to rest on their laurels. Instead the obvious next step was to design a bike that blew the SL7 out of the water. Besides, when you've got race-winning athletes riding your bike day in and day out, it's hard not to find something to improve upon. Since the SL7 did a lot of things just right, the SL8 retains practically identical geometry and 32mm tire clearance, retaining the versatility that higher volume tires allow for.

Tarmac SL8


The new Tarmac SL8 builds on the aerodynamic elements of the SL7; Specialized engineers used the Win Tunnel to design and test their designs to improve aerodynamic efficiency on the Tarmac SL8 where it matters most. Taking a different approach to other brands though, their end goal was not the most aerodynamic bike, but aero where it matters, and building in stiffness and weight savings where it doesn't. This results in a front end and seat tube with incredibly aerodynamic properties that balance weight and stiffness, but a rear triangle, down tube and top tube that are focussed entirely on optimal weight and stiffness. This results in a bike that's both fast and handles incredibly.

Focussing on leading-edge areas with the most drag, Specialized honed in on three key areas; the cockpit, head tube and seat tube. Starting with the cockpit, they utilized the new Roval Rapide cockpit on S-Works models (also available aftermarket) shaving 4 watts of drag over the already fast 2-piece bar and stem by eliminating the cluster of bolts in that area. At the head tube, Specialized engineers moved the steerer tube back, giving more freedom to create an aerodynamic shape up front resulting in the 'speed sniffer' nosecone shape, creating more clean air behind it. Lastly the seat tube is the thinnest, most aero seat tube Specialized have ever designed, with the same tube profile as the SL7's seatpost, leaving the seatpost on the SL8 to be thinner and build in more compliance for rider comfort.

Tarmac SL8

Weight Saving

Taking what they learned from the Aethos; the lightest production road frame in the world, Specialized applied the same carbon layup techniques to the SL8 that allowed them to remove unnecessary weight while using tube shapes that build in stiffness or compliance where needed. The result is a 685g (56cm FACT 12r) frame that saves 15% or 115g over the previous SL7 frame and 275g over the Venge. The lower level FACT 100r weighs in at 780g, still 20g lighter than the previous S-Works frame. A strict diet on the rest of the frame components and pieces makes for a whopping 500g weight saving on the complete bike; a fact that would be breaking news in itself, and is mind blowing when combined with increased stiffness and aerodynamics. 

Tarmac SL8

Stiffness and Compliance

The Tarmac SL8 has a 33% improved stiffness-to-weight ratio over the SL7, which considering it's dropped 15% in weight, is pretty damn impressive that it's also stiffer. A stiffer frame means better power transfer and efficiency - because every watt counts when you're battling for fractions of a second. Not only this, but the SL8 is 6% smoother, helping with fatigue on longer rides, because fatigue matters when it comes to big days in the saddle.


The Tarmac SL8 is the fastest bike Specialized have ever made. Designed to be the fastest bike in the peloton and on the top step of the podium it combines incredible speed with a more comfortable ride, low weight and aero efficiency. When put head to head with the SL7 and Venge it came out ahead every time no matter the scenario. The SL8 is the bike to have if you're looking for raw speed, racing or a high performance bike for your day to day riding. Because performance isn't just for the pros.

Tarmac SL8 Dura Ace


Starting at the Expert spec with the FACT 10r frame and fork, riders still get the S-Works seatpost, an integrated bar and stem, Power Expert saddle and a Sram Rival eTap AXS wireless 12 speed groupset rolling on Roval C38 wheels and weighing in at 7.77kg (17lb 2.1oz) in a 56cm.

Next up is the Pro spec still with the FACT 10r frame, upgrading to a carbon Roval Rapide handlebar and Rapide CL II wheels on 350 hubs, Power Pro saddle with ti rails and available with either a Sram Force eTap AXS (7.44kg, 16lbs 6.4oz) or Shimano Ultegra Di2 12sp groupset (7.16kg, 15lbs 12.6oz) both with integrated power meters. 

At the top end of things are the S-Works builds in either Dura-Ace or Sram Red build kits. These come with the Roval Rapide cockpit, lightweight FACT 10r frame and fork, carbon S-Works Power saddle, Rapide CLX II wheels and of course either a Sram Red (6.85kg, 15lbs 1.6oz) or Shimano Dura Ace (6.62kg, 14lbs 9.5oz) groupset.

Finally there are two frame-only options, both are the S-Works FACT 12r frames and come with seatpost, ready for the build of your dreams. One is painted and ready to go weighing in at (1.41kg) 3lbs 1.7oz including fork, headset, seat clamp, seatpost etc. The other is a ready-for-paint frame that can be painted or run as-is at a super-light 1.37kg (3lbs 0.3oz).

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Tarmac SL8