Cervelo S5 Disc launched - disc brakes and new V-shaped stem

Cervelo has today launched the brand new S5 Disc, a complete redesign of its flagship aero race bike, in the process giving it the disc brake treatment. The company claims the new bike is "42 grams faster than its predecessor - that’s the equivalent of 5.5 watts*."

The previous S5 has regularly been held up as one of the fastest aero bikes but it’s been four years since it was last updated, after being first unveiled in 2011. Cervelo has been a fading light at the cutting-edge of the sport for the last few years as its rivals, not helped by the departure of founder Gerard Vroomen and engineer Damon Rinard.

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So the new S5 Disc is an important bike for the company, especially as it has also been revealed it’ll be replacing Giant as bike sponsor for Team Sunweb.

“The S5 is an aerodynamic road bike built for the fastest sprinters in the world. It is stiffer and more aerodynamic than ever before while offering excellent comfort and ride quality. If you live for the exhilaration of going fast, the S5 will give you every possible advantage,” describes Cervelo of the new bike.

At first glance, the frame looks startlingly similar to the previous model, but look closer at the front-end and you’ll notice a radical redesign of the fork and stem.

Frontal surface area is hugely important to improving aerodynamics, and to this end, Cervelo has developed a V-shaped stem integrated into a new full-length external fork.  The V-shaped stem reduces drag by, according to Cervelo, allowing unimpeded airflow along the top tube and routing all the cables and houses inside.

There’s also a redesigned handlebar with an airfoil shape that has been twisted from centre to edge which Cervelo says improves airflow.

That’s not the first time we’ve seen this approach. The original Factor Vis Vires (still one of the fastest bikes I’ve ever ridden) used the same concept. And more recently there’s the BMC TimeMachine time trial bike which also has an external fork with a V-shaped stem.

The Cervelo stem arrangement allows a reasonably wide range of fit adjustment. You can choose from five stem lengths, four bar widths, 5-degree of handlebar rotation adjustment and 32.5mm of stem spacers.

Moving to the rest of the frame, there’s an aero shaped downtube that now sits very close to the front wheel, so close in fact they’ve had to shape the downtube to wrap around. The seat tube still follows the shape of the rear wheel but it’s a much smaller profile than before, with a slimmer straight section of seatpost. All cables are internally routed and there’s a choice of two bottle cage positions on the downtube, the lower one promising lower drag.

What you can’t see in the photos is the revised geometry. Cervelo has made the new S5 longer and lower, just as it did with the R5 actually, which was in response to feedback from the professional riders using its bikes. The stack has been reduced, lowering the handlebar height, and the reach is longer too.

The bottom bracket has also been dropped to lower the rider’s centre of gravity and provide better stability at high speed. Also contributing to greater stability is increased fork trail up to 57mm.

There are five sizes to choose from, a size 56cm has a 565mm stack and 392mm reach, a 73.5-degree head angle, 155mm head tube length, 70mm bottom bracket drop and a 982mm wheelbase.

Aerodynamics are obviously important for going fast, but you know the pros love a stiff frame right? It won’t surprise you to learn that Cervelo is claiming the new S5 Disc is 25% stiffer around the bottom bracket - where it’s still using its BBRight standard - and 13% at the head tube.

Comfort isn’t a huge concern to racers, but the new bike will take up to 28mm tyres and layup and shape of the rear stays has been refined to offer a small amount of bump absorption.

The new Cervelo S5 Disc will be available in four builds priced from £4,899 with an Ultegra groupset up to £9,699 with Dura-Ace Di2.

Wondering where the new Cervelo S5 rim brake bike is? There isn’t one I’m afraid.

*compared to Cervelo’s generation 2 S5 with its AB04 aero handlebar.

The above photo shows the evolution of the Cervelo S5.

More at www.cervelo.com