Remember Zertz? Check out Tom Boonen’s 2012 Specialized S-Works Roubaix SL4

We’re heading all the way back to 2012 for this edition of Bike at Bedtime and the super-interesting Specialized S-Works Roubaix SL4 that Tom Boonen rode to victory in Paris-Roubaix.

Belgium’s Boonen had a stellar season in 2012. As well as his Paris-Roubaix win, he took victory at races including E3 Harelbeke, Gent-Wevelgem, and the Tour of Flanders. The picture above is from Paris-Roubaix with Boonen aboard the yet-to-be-released Specialized S-Works Roubaix SL4 (he won Gent-Wevelgem aboard an S-Works + McLaren Venge and was on an S-Works Tarmac for the Tour of Flanders).

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 introduced 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 compliance the frame provided with the Zertz located in the fork and in the seatstays.

Zertz? That’s the name that Specialized gave to the viscoelastic inserts it included on the Roubaix at the time, designed 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?

For the SL4, 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 that had always been the Roubaix’s key feature.

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 of the comfort. 

The fork and head tube were tapered, the idea being to balance torsional stiffness with a degree of compliance, while the tubes and layups were independently designed for each frame size. The aim was to get a uniform level of 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 one for his Paris-Roubaix win. The Cobl Gobl-R (C-GR) used a leaf spring design with a Zertz insert sandwiched in the gap, the idea being to double the amount of compliance on offer. 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 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, 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.

Boonen’s Omega Pharma-Quick Step team used SRAM's top-end Red groupset, and he rode Zipp 303 wheels. 

Of course, 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? It was simply because of the increased possibility of a puncture over the cobbles, and the faster speed at which a rim brake wheel could be swapped, according to Specialized. 

> Pro Bike: Tom Boonen’s Specialized LTD Roubaix - with rim brakes and not discs

The Roubaix has changed hugely since 2012, the latest version coming with Specialized’s Future Shock 3.0 suspension technology and clearance for tyres up to a whopping 40mm wide. Find out all about it here.

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.

Check out loads more Bikes at Bedtime here.