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Tuesday, July 5, 2011
The Cervelo S5 The Fastest Road Bike – In The World
Since 2001, when Cervelo introduced their first aerodynamic road bike, the aluminum "Solo," their aero road bike designs have been considered the industry standard. The fastest frame in the world in its day, the Solo was the first road bike with airfoil shapes specifically tuned for the speeds and wind angles cyclists experience. In 2005, Cervelo released the Soloist Carbon, which was showered with awards and rave reviews for its aerodynamic prowess, as well as its handling, stiffness, and ride quality. That design has remained relatively unchanged, with only minor tweaks and improvements through the S3, which was introduced in 2008. Despite the arrival of competitors in the aero road bike market, Cervelo held that the S3 remained top dog in the wind tunnel...until now.
This is not merely another iteration of the S3, but a completely new frame, with new features never seen before on a road bike. The S3 has been dethroned.
Overview
The S5 combines many of the best features of the P4 TT bike and the R-series lightweight bikes, giving rise to a road frame with all new geometry. The result, according to Cervelo, is a bike that has 12% better stiffness, better aerodynamics, and the comfort of the S3, and also weighs 80 grams less. At 25mph the S5 will save a rider 9 watts compared to the S3. And compared to many round-tube, non-aero frames, the S5 can save up to a whopping 32 watts at 25mph. Even in a pack, where aerodynamic drag is reduced by 25 to 30 percent, a rider would still be saving between 6 and 20 watts. Anyone who owns a power meter should be familiar with how much of an advantage that can be. But the S5 isn't just slippery, it is also stiff and light and displaying amazing handling acumen under the guidance of Thor Hushovd in the 2011 Tour de France. Stiff and light enough for 180lbs of Thor to climb the Pyrenees, nimble enough to chase climbers down on rainy descents.
The S5 features deep, airfoil seat stays which are very similar to those found on Cervelo's top TT bike, the P4. The shape is especially complex where it attaches to the seat tube, which serves to improve aerodynamics, shield the rear brake caliper, and provide extra vertical compliance for comfort on bumpy roads.
The S5 features a seat tube that is currently unique among road bikes. No other road bike has such a large extent of rear wheel coverage, and keeps the rear wheel in such close proximity to the seat tube cutout. This shields the rear wheel from the air, reducing aerodynamic drag. As the dropouts remain vertical for easy wheel swaps, this will limit tire size options somewhat. Cervelo reports that 23mm tires will fit, as will some models of 25mm wide tires.
There is more to a road bike than aerodynamics. Road races often involve steep mountains where weight matters too. Cyclists sprint, attack, and corner at the limit, and stiffness is important for solid handling and power transfer. While the S3 has proven stiff and light enough for powerful riders like world champion Thor Hushovd, the S5 improves on the S3 by 12% in stiffness and 80 grams in weight. Part of this is achieved with the BBright system, first featured on the R-series frames. The asymmetric bottom bracket and chain stay design allow for a bottom bracket/crankset system that can be lighter and/or stiffer than a standard setup.
Another feature reminiscent of the P4 is the dropped down tube. Cervelo combines an integrated fork that fits neatly into the frame and a dropped down tube that hugs closely to the front wheel. The design maintains an airfoil leading edge along this curve around the front wheel, rather than a cutout, which would add drag whenever the wheel is not pointed exactly straight ahead.
A common point of skepticism about aero frames for bike racers is whether it is worth paying for sculpted aero down tubes and seat tubes if you are going to load them up with water bottles anyway. While Cervelo has maintained that aero tubes are faster than round ones even with bottles in front of and behind them, the S5 offers two features to improve on water bottle equipped performance. The first is a feature also found on the latest Lightspeed aero road bikes – a widened trailing edge on the down tube to shield the bottles from the air. Cervelo takes this water bottle philosophy a step further by offering two mounting positions for the down tube bottles. There is a low position to be used when carrying a single bottle, which reduces the gap between the bottle and the seat tube, smoothing airflow. When using two bottles, a higher mounting point is used that positions the two bottles close to each other to optimize airflow. This is another feature unique on the market right now.
Specs, Pricing, Availability - Update: ATC has S5s in stock and ready to ride!
The S5 model is a bit of a departure from previous Cervelo frames in that it will be offered in 3 levels of carbon fiber. The shape and stiffness of each offering are identical, with the only change being a reduction in weight as you move up the scale. The great news is that the S5 is not just going to be an expensive superbike like the R5ca. In fact, the entry level S5 comes in cheaper than the S3. For the weight weenies and people who simply want the best, you can pay more to have your cake and eat it too. The standard and team frames will be available at Austin Tri-Cyclist starting this August with the super light VWD frames available starting in January 2012. The S5 trim levels are as follows:
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