With the 2026 Paris-Roubaix behind us, let’s head all the way back to the 2012 edition of this legendary race and check out the then-new Specialized S-Works Roubaix SL4 that Belgium’s Tom Boonen rode to victory, complete with rim brakes, mechanical shifting, and Zertz inserts that were said to smooth the ride.
To say that the former World Road Race Champion Tom Boonen was successful over the cobbles really doesn’t cover it; he was a monster over the rough stuff. Of the most prestigious cobbled races, Boonen won E3 Harelbeke five times, Gent-Wevelgem and the Tour of Flanders three times each, and Paris-Roubaix a record-equalling four times. He won all four of these races in 2012, the only rider ever to do so in a single year.
The picture above is from Paris-Roubaix with Boonen aboard the yet-to-be-released Specialized S-Works Roubaix SL4.
Specialized introduced the Roubaix in 2004 and Boonen rode the second incarnation, the SL2, to back-to-back Paris-Roubaix victories in 2008 and 2009. The SL3 was released in 2010, and then we first saw the SL4 model when Boonen rode it in 2012 before its introduction into the 2013 range.
Specialized said that the goal with the Roubaix SL4 was to tune the level of frame compliance with the Zertz located in the fork and in the seatstays.
Zertz? That’s the name Specialized gave to the viscoelastic inserts it included on the Roubaix at the time, said to soak up irregularities and smooth the ride, and keep the bike planted on rough roads, rather than skittering and jumping. In truth, the damping was actually down to the shaping and layup of the carbon, and the Zertz just filled the space, but that’s not such a good PR story, is it? Specialized stopped using Zertz inserts with the introduction of the 5th generation Roubaix, introduced in late 2016 for the 2017 model year, replacing them with the Future Shock suspension system built into the head tube.
For the SL4, though, Specialized altered the placement of the Zertz. Whereas they were previously positioned in a hole in the middle of the fork leg and seatstay, they were moved to a gap on the edge of each. In other words, rather than being fully contained within the carbon structures, the Zertz were enclosed on only three sides.
Specialized said that it wanted to provide the Roubaix SL4 with a sharper and more focused ride feel than previously, bringing it a little closer to the race-focused Tarmac while still offering the extra comfort for which it was well known.
With that in mind, the Roubaix SL4 borrowed some of the Tarmac’s frame construction features. The bottom bracket and asymmetric chainstays were a one-piece module, for example. The seatstays were wider and straighter than before, making for a stiffer frame, Specialized said, without sacrificing too much comfort.
The fork and head tube were tapered, the idea being to provide torsional stiffness with a degree of compliance, while the tubes and layups were independently designed for each frame size. The aim was to create uniform performance across the range. The steerer tubes were size-specific, for example, so Specialized had to design three new forks for the Roubaix.
As well as Zertz inserts in the frame, the Roubaix SL4 came with a new Cobl Gobl-R seatpost, although Boonen didn’t use it for his Paris-Roubaix win. The Cobl Gobl-R (shortened to C-GR) used a leaf spring design with a Zertz insert sandwiched in the gap, with the aim of doubling the amount of compliance on offer, according to Specialized. The idea was that it didn’t flex vertically during normal pedalling, but it did respond to bigger hits.
When we rode a disc-brake version of the Roubaix SL4 at Eurobike in 2013, we said, “The CG-R post is actually more solid than it looks. It doesn’t flex as soon as you sit in the saddle, but you can feel that it’s quite active as you ride along. Specialized reckons it will provide up to 18mm of movement if push comes to shove.”
> First Ride: Specialized S-Works Roubaix SL4 Red Disc
As mentioned, though, Boonen didn’t make use of this design, sticking with a more traditional – non-kinked – seatpost from Zipp.
Specialized was keen to point out that Boonen had had his position tweaked as a result of the brand’s Body Geometry FIT (Fit Integration Technology) system, which it was keen to promote, working with fit technicians and specialist fitting tools. His handlebar width went from 46cm to 44cm for better aerodynamics, for instance, and he raised his saddle height slightly too. Bear in mind that Boonen had been one of the world’s most successful pro riders for a decade at this point.
Boonen’s Omega Pharma-Quick Step team used SRAM’s top-end Red groupset with mechanical shifting (SRAM didn’t announce its first Red eTap wireless groupset until 2015), and he rode Zipp 303 wheels.
Naturally, Boonen used rim brakes for his 2012 Paris-Roubaix win. Disc brakes weren’t permitted in the pro peloton at the time. Boonen did switch to disc brakes on the road later in his career, but he rode a Specialized Roubaix with rim brakes for his last-ever Tour of Flanders in 2017, by which time the production version was available only with discs. How come? Specialized said it was because of the increased possibility of a puncture over the cobbles, and the faster speed at which a rim brake wheel could be swapped.
> Check out Tom Boonen’s 2017 Specialized LTD Roubaix – with rim brakes and not discs
The Roubaix has changed hugely since 2012, the latest versions coming with Specialized’s Future Shock suspension technology – either the 3.2 or 3.3 version, depending on the model you go for – and clearance for tyres up to 40mm wide. Find out all about it here.
> Read our review of the Specialized Roubaix SL8 Expert
Tom Boonen retired from racing in 2017, although he has been involved in many projects in the world of cycling since then, including supporting Classified’s Powershift drivetrain.
