Canadian frame builder Cervélo, the bike sponsor of the Garmin-Cervélo team, has launched the new S5 frame, which claims significant aerodynamic advantages over the S3, its existing top aero frame. The new bike will be ridden by the team in the Tour de France, which starts on the Passage du Gois, on France’s west coast, this coming Saturday.
Even at first sight, there are considerable differences to the S3, with probably the most obvious being the extended cutout to the seat tube, whose lines follow the rear wheel in a way reminiscent of Cervélo’s S3 and S4 time trial frames. This feature smoothes the airflow from the frame to the wheel, helping it to cut through the air more efficiently.
The down tube has been dropped on the S5, compared to the S3, which is another measure designed to smooth the flow of air across the frame; the measure is also claimed to minimise turbulence behind the fork crown. At the rear end the seat stays have been deliberately engineered to shield the brake calliper, which, unlike many aero frames, stays at the top where they join the seat tube instead of moving down to the bottom bracket area.
To keep the frame as stiff as possible, the S5 uses Cervélo’s oversized BBright system at the bottom bracket. The asymmetric shape, along with the oversized down tube, seat tube and chain stay join, creates what the company says is an ultra light and stiff pedalling platform.
Lastly, the frame is what Cervélo calls built for bottles, with the down tube shielding the cages in their traditional places; allowing the air to flow more smoothly over the area, whether using one bottle or two.
Cervélo has calculated that the S5 will save 36.8 seconds over 40km over the S3, which it considered to be the ultimate aero road frame. This equates to 0.92 seconds per kilometre, or 92 grams of drag, which gives a power saving of
9.2 watts.
The S5 is also 12% stiffer than the S3 and around 80g lighter, with a frame weighing as little as 990 grams, including paint and metal parts.
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