Cervélo thinks their new aero disc brake S3 Disc will be a workhorse racer

Cervélo says that they wait to introduce a new bike until they can see really significant performance gains to be made. So they had been working and working on bringing disc brakes to their World Championship winning S3. And now they are ready; the new S3 Disc is said to surpass the current rim-brake aero bike in both overall stiffness and a bit surprisingly aerodynamics. Building on the lightweight tech they grew out of their Project California shop, Cervélo sees the disc brake S3 Disc developing as their new everyday workhorse race bike, and they expect to see it put riders on the podium, as soon as the UCI will allow…

Cervélo claim to have taken every element that made the S3 fast and such a successful race machine and taken it up a notch for the new disc brake version. At first glance the new S3Disc looks strikingly similar to its predecessor, with similar tubing shapes throughout.

A lot of what sets the bike apart happened inside of the mold. Cervélo tell us that the lessons they’ve learned on their superlight bikes produced in California have enabled them to better refine their mix of carbon fiber plies and really develop layups that can improve stiffness in almost any shape tube, without adding weight. That has let them essentially keep the same aero tube profiles that they had developed throughout the lifetime of their S-series bikes, which balance both vertical compliance for long race comfort and predictable handling in a wide range of crosswind conditions.

They say the addition of disc brakes and the improved stiffness make this a bike that will offer a lot more versatility than the current S3. And they expect it to be ridden as much as an everyday road bike by amateurs, as it will be raced for sprint finishes.

The performance improvements are real and show the true progressing of their carbon design and construction. Compared to the rim brake S3 the new S3 Disc claims to be two watts faster, 9% stiffer, and 40g lighter. Sure those are all fairly incremental changes, but when everyone was talking about putting disc brakes on road bikes just a year ago, it was always about compromise. This Cervélo S3 Disc is the latest reminder that good engineering can lead to improvements, not just in better braking, but in pretty much every metric of evaluating frame design.

While it seems small, mounting the rear brake on a chainstay flat mount helped clean up rear brake routing, bringing it all internal from the head tube. The same thing happens in the fork, with much less exposed housing below the headtube. The use of electronic groupsets never hurts the aero setup either, and the S3 Disc’s top Ultegra Di2 build does a good job of limiting cables out in the wind.

The frame redesign is pretty minor, other than using a rear triangle and dropouts that take more inspiration from the Rca frame than the S3. There it gets a new full carbon 12mm thru-axle dropout that delivers light weight and measurably increased stiffness, for overall improved handling through the corners. Where the new chainstays hit the asymmetric 79mm wide BBRight bottom bracket, they’ve also reworked the carbon layup to boost power transfer stiffness.

Pulling a solution from the S5, the new S3 Disc gets the same internal Di2 battery location inside the downtube, that has easy access via the semi-external BB cable guide.

It gets the same low slung and flattened rear edge of the downtube  that lends stiffness and a smoother transition over the water bottles. It does get updated cable routing that is more modular to deal with all types of drivetrains and brake systems. (Remember that both wireless and hydraulic disc brake drivetrains are due any day!) Cervélo calls it improved tire clearance, but they still see this as a speed-oriented race bike, which means it keeps the rim-brake version’s max 25mm tire width.

While the frame shapes are mostly the same, including the carry over rear wheel cutout, the fork does get a new revised airfoil profile to its legs. And it is there that they claim most of the aero improvement with a 19g drag reduction. Pulling brakes away from the fork crown also allowed the engineers to add more open space above the tire, and at the same time the spread the legs open a bit, both of which helped to clean up airflow around the fork.

Geometry wise, the S3 Disc gets an identical fit to the current S3 for classic quick road handling. The S3 Disc uses a new 2-position seatpost to get either a standard or more forward position on the bike a 0mm offset seatpost on the two smallest frame sizes and a 25mm offset on the rest. Two complete Ultegra bike builds will be available with either Di2 or mechanical 785/685 shifting and hydraulic 805 braking for both. The S3 Disc will come in either a white/flouro paint job or a more brand traditional red & blue.

Cervelo.com