Aero with Cervélo: The New S5

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Out in the northeast corner of Tucson, AZ, Saguaro National Park is a place of rolling hills ripe with the flora of its namesake. The park has an eight-mile loop that winds through its acreage. For the Cervélo S5 — a best-in-class aero-road bike that just upped its own ante — it’s a playground built for speed. The bike, in all its wind-tunnel-tested fluidity and lab-engineered stiffness, rips through the open fields like it’s made to breathe this arid land’s air.

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Understanding the new Cervélo S5 requires a look at its forebearer. The first iteration was born of Cervélo’s interest in adapting the speed of their time trial bikes into the stiffness and lightness of their road bikes. It became a best seller. But Cervélo engineers weren’t satisfied. They sat down and filled three white boards with improvements. They narrowed to “31 Things”, tweaks and details, some know-how pulled from their work on the RCA project, some from rider feedback, and some things they just knew could be better.

The Route to Ride
While the eight-mile Saguaro loop highlighted the S5’s best characteristics — snappy sprints and stable handling — it is the Mt. Lemmon climb that allows the bike to differentiate itself. The ascent is 21.5 miles of a straight uphill, and the road’s a Tucson tradition. It rewards with ample views and changing landscape — you’ll know you’re about halfway when the cacti stop and the high-desert pines come into view.

Here are a few things that changed: the stack height dropped (15mm lower on a 56cm frame); the downtube is closer to the front wheel (reducing drag); the front fork allows for full rotation; the carbon aero handlebar was designed from the ground up; the bond joints on the seat stays are lower; the integrated cables are future proof designed (allowing for hydraulic, mechanical and electric iterations). The list goes on — but to really appreciate the changes, you need to ride the thing.

The Saguaro loop is a showroom for the S5’s abilities, with small kickers, smooth curves, fast flats, and one short climb. The bike rips through the course at full throttle, and that’s what it wants most: to go fast. But speed requires stability, and perhaps the most impressive part of the S5 is its assurance that the bike is in control. The handling is steady, almost eerily stable for a bike this quick.

In the drops or on the saddle, the bike is stiff and snappy underfoot. Graham Shrive, the S5 Project Manager, noted that “to improve the S5, it’s got to be stiffer.” Stiffer it is, with 35 percent higher headtube stiffness and 17 percent higher fork lateral stiffness. The team accomplished those increases without adding weight.

The S5 Di2 Dura Ace edition comes equipped with HED Jet 6 Plus SCT wheels and a Fizik Antares seat. Paired with the frame, they offer a smooth ride that responded to the road without being jostled by it. The bike feels (and is) light, trumping the hallmark claim of performance road bikes, and the aero design puts nothing in the way of acceleration save the rider’s own legs. It’s quick, and has a ton of torque on the top end.

In wind tunnel testing, Cervélo noted that 30 percent of total drag on most bike frames comes from handlebar assembly (next most significant drag was 16 percent front wheel and 16 percent frame). So they set out to improve it. Their new Cervélo All Carbon Aero Handlebar is manufactured in house, and is built to increase the aerodynamic potential of the bike. The flat bar has the look of an airplane wing, and directs air around the bar rather than blocking its path. It keeps the stem mount streamlined, with a small gap in the middle of the bar. The only drawback is for an out-front computer mount, which currently doesnt’ have a place on the bar.

Of course an aero bike will go fast on the flats and small spins through an eight-mile loop — but the real challenge comes on a climb. Thus, we head to Mt. Lemmon, a 21.5-mile climb that ascends with a steady and unrelenting 5-6 percent grade. Here the bike proved it can climb, and neither of the typical trump cards a performance bike holds over an aero frame — heavy weight and sluggishness on the climbs — applies.

The S5 is an overachiever. Of course, you won’t buy this bike as a climber (look to the R5 or RCA if you’re only hitting hills) but, for the sprinter or rider looking to lead the pack without having his frame hang him on the hills, the bike outperforms.

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