The hotly anticipated Specialized Tarmac SL8 focuses on low weight, compliance, stiffness and speed to make it the “fastest bike [it has] ever produced”.
Specialized has largely stuck with the winning ingredients of the Tarmac SL7 but set out to increase compliance and improve aerodynamics, primarily through the use of its elongated Speed Sniffer head tube and a new integrated bar-stem.
The brand has also trimmed the fat, resulting in a feathery 685g claimed frame weight for a size 56cm.
The second-tier FACT 10r frames have undergone a revamp too, with a 780g claimed frame weight (also in a size 56cm), 20g lighter than the SL7.
Tarmac SL7 meets Aethos?
The Specialized Tarmac SL8 is the latest iteration of the brand’s all-rounder race bike.
The S-Works Tarmac SL8 continues to be constructed from what Specialized calls its FACT 12r carbon fibre.
Specialized says it has overhauled the bike’s 'leading edges', with the brand claiming the SL8 is 16.6 seconds faster than the third-generation Venge aero bike at 45km/h.
The SL8’s tube profiles are marginally rounder and more svelte than the SL7’s, which makes them lighter and enables them to bear the load of the rider more efficiently, according to Specialized.
The Aethos-inspired tube shapes are said to improve compliance, with Specialized claiming a 6 per cent increase in comfort through the saddle over the SL7.
Specialized has also stiffened up the bottom bracket, head tube and fork, claiming a 33 per cent stiffness-to-weight ratio gain.
The head tube, dubbed the Speed Sniffer, is said to improve aerodynamics thanks to its pronounced leading edge that almost hangs over the fork.
Also claimed to improve aerodynamics is the revised seat tube, which sports a narrower profile and houses a new proprietary seatpost.
Tyre clearance remains at 32mm and the bike uses a BSA threaded bottom bracket standard.
Specialized says it has preserved the geometry and handling characteristics of the Tarmac SL7 for the new race bike, but with the stack increased by 10mm to account for the new Roval Rapide cockpit.
The Roval Rapide integrated bar-stem replaces the two-piece setup of the SL7. Specialized claims the new design saves 4 watts. There are 15 options to choose from, with bar widths ranging from 38cm to 44cm and stem lengths of 75mm to 135mm.
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A heady spec for a heady price
We’ve got the all-bells-and-whistles S-Works Tarmac SL8 Dura-Ace Di2 in for testing, which retails for £12,000/$14,000/€14,000/AU$19,900.
There’s also a SRAM Red eTap AXS equivalent build for the same price.
An S-Works frameset retails for £4,750/$5,500/€5,500/AU$8,900, while the FACT 10r carbon variant will set you back £3,000/$3,500/€4,000/AU$5,600.
The model we have features a Satin Fog Tint/Green Ghost Pearl/Red Ghost Pearl Fade paintjob – essentially a pearlescent matt white that glimmers in the sun.
As the model name suggests, our test bike comes with Shimano Dura-Ace Di2 R9200. The electronic groupset pairs a race-oriented 52/36t chainring with an 11-30t cassette and also includes a 4iii Precision Pro dual-sided power meter.
Specialized’s in-house components brand Roval provides the Rapide CLX II wheelset. These 60mm-deep hooked carbon rims have a 21mm internal rim width, and the front and rear wheels have distinctly different shapes to reduce drag and increase stability, according to Specialized.
The AeroFlange hubs feature ceramic bearings and DT Swiss Ratchet EXP freehub internals, laced to the rim with DT Swiss Aerolite spokes.
Specialized’s S-Works Turbo RapidAir 2BR tyres are installed onto the rims in a rather narrow 26mm width.
Elsewhere, an S-Works Power saddle with carbon rails is fitted to the proprietary 15mm-offset seatpost.
The Roval Rapide cockpit is wrapped in Supacaz Super Sticky Kush handlebar tape.
On the BikeRadar scales, our size 56cm Tarmac SL8 weighs in at 6.76kg, without pedals. That’s a smidgen under the UCI weight limit, however once fitted with a set of the best road bike pedals and two bottle cages, it will likely hover around the 7kg mark.
Senior technical editor Ashley Quinlan took a first ride on the bike in Glasgow, Scotland and will be bringing you his full verdict after further testing.
