Specialized S-Works Roubaix SL4 Disc Di2

The Roubaix SL4 had one hell of a debut when Tom Boonen rode it to a solo victory in Paris-Roubaix. But that was in 2012. Specialized has breathed new life into the platform with hydraulic discs that let the Roubaix stop the way it rides: on any road, in any conditions, in a WorldTour-worthy package.

In fact, where other manufacturers have jumped into the endurance category by doubling down on comfort, Specialized actually stiffened up the Roubaix SL4 over the previous generation. This is a race bike that just happens to be a bit more upright and relaxed (190-millimeter, 72.5-degree head tube) than pure racers, and with better vibration damping.

As always for the Roubaix, Specialized has built elastomer Zertz inserts into the fork and seat stays to help tame vibrations. And certainly the 26-millimeter S-Works Turbo tires helped enhance comfort. (There’s clearance for 28-millimeter tires.) But beyond delivering comfort through geometry and those now-familiar component choices, the Roubaix also features Specialized’s CG-R seat post. In addition to providing some compliance via its narrow (27.2-millimeter) dimensions, the post has an ungainly kink at the top that houses yet another Zertz insert. The reason is obvious: a bit of suspension right where you need it most. I’m not a fan of single-bolt seatposts, especially on a bike that’s intended to be ridden on rougher surfaces, but the CG-R does seem to take some of the sting out.

Those extra concessions to comfort are likely necessary to preserve the Roubaix’s characteristic forgiving ride quality, given the ways Specialized has stiffened up the frame. It’s still no pure racer — the lab data is great for the category but falls short of what you’d want in a sprint — but the frame does have more snap than in the past. If previous incarnations of this bike favored comfort over performance, those two qualities now receive equal billing. You get a long wheelbase but also a race-worthy bottom bracket. There’s a cushy seat post but also deep-section Roval Rapid carbon clinchers built around Ceramic Speed bearings. It’s impossible to have the best of both worlds when those two worlds are speed and comfort. But the Roubaix balances them superbly.

Component Highlights: Shimano Dura-Ace Di2 drivetrain with 11-28 cassette; Specialized S-Works FACT carbon 50/34 crankset; Roval Rapide CLX 40 carbon disc wheels