Cervelo P4

CERVELO P4

A Cervelo P4 entra no mercado em 2009 como a bike mais rápida do mundo, segundo avaliações em tuneis de vento! A P4 tem como novidades as formas dos tubos mais aerodinamicas ainda, garfo customizado integrado praticamente sem espaços entre o head tube e o down tube, o freio traseiro acoplado no quadro e o sistema de hidratação acoplado no quadro (sem necessidades de caramanholas).

Simplesmente fantástica!

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Introduction
The P4 is the eagerly anticipated successor to the current time trial standard, the Cervélo P3. As the P3 is still the fastest bike available three years after its introduction, it is clear that creating its successor was no easy task. After millions in research & development and over two months of intensive testing at the San Diego Low Speed Wind Tunnel, the P4 is the fastest bike ever in the wind tunnel, including both UCI-legal and illegal bikes.

“The P4 is the biggest leap we have ever made in aero bike technology,” said Phil White, co-founder of Cervélo. “The P series has evolved significantly over the last decade, making it a real challenge to keep finding improvements. With the P4, the mandate was to make it significantly faster than the P3 while achieving equivalent or better performance relative to stiffness, power transmission, low weight and comfort. I’m pleased to report that we have met those goals.”

The strengths of the P4 are found in its many fine details, some of which are quite visible but others are difficult to detect at first glance. The key to the performance of the P4 lies in the frameset’s integrated design. This System Engineering approach, which considers the frame, components, wheels, hydration and the rider together, generates substantially reduced drag values in virtual (CFD) and physical wind tunnel testing. Highlights of the P4 system include:


Optimized Aero Tube Shapes
The aero profiles of the P4’s tubes are completely new, improving airflow attachment and reducing turbulence relative to other designs. In addition, the new asymmetric aero chain stays generate very low drag values, particularly in cross-wind environments, compared with chain stay designs from earlier P-series and competitor models. Finally, the seat stays are pitched forward to reduce frontal surface area and their joints with the seat tube are optimized for maximum aerodynamic efficiency.


Fork
The custom fork, developed by vroomen.white.design, is integrated seamlessly into the head tube and downtube. This feature was first conceived by Cervélo in 1995 and comes to fruition now on the P4. Cervélo also invested significantly to optimize the spacing between the tires and wheels, the frame and the fork. This is a very complex area aerodynamically and our engineers tested over seventy-five different designs during the development process. The result is a significant reduction in drag values generated in this section of the bike.


Front wheel cutout
We invented the front wheel cutout back in 1995, but in subsequent testing we have found it not to be the fastest design. So despite current trends the P4 does not have a front wheel cutout, as we have never seen one that works. While front wheel cutouts can show good drag values in the tunnel, this is only the case because there, the front wheel is perfectly in line with the downtube. In reality, the rider constantly makes small steering adjustments, which stalls the airflow onto the downtube and increases the drag.


Rear Brake
The P4’s custom rear brake is fully integrated into the frame design. The brake, fully designed and developed by vroomen.white.design, is recessed into an alcove immediately behind the bottom bracket. By using a recess instead of placing the brake above or underneath the chainstays as is commonly done, the brake is not only invisible to the eyes but, more importantly, to the wind. Thanks to the structural carbon brake booster, the brake has the same power and modulation as a Dura Ace brake while being 30% lighter. The brake booster is easy to remove for full brake service and allows access to the brake mechanism for quick adjustments on the road.


Hydration
Hydration has long been a challenge on aero bikes, with traditional bottle shapes corrupting the efficiencies of proper airfoil tubes. The 570 ml water bottle on the P4 smoothly integrates the down tube, seat tube and bottom bracket in a single aero form. The design reduces the drag typically associated with bottles mounted on the down tube, seat tube or behind the saddle and in fact, the P4 is faster with the bottle than without.

The bottle is the same for all frame sizes, is easy to grab, easy to drink from and refillable on the go. P4 owners have the option to replace the bottle with a utility box (handy for Dura Ace 7900 batteries, spare tubes, CO2 and tools) or a structural stiffener.


Summary & Availability
While the features described above are significant contributors to the P4’s overall performance, the greatest gains have been made in the dozens of small details. Look for more detailed information in the near future. The P4 will be available as a frameset in late December 2008.


Geometry

Cervélos fit better. In the end that is the main reason why they have become the most popular time trial & triathlon bike in history. Of course we have unparalleled aerodynamic know-how, and the frames offer great power transfer and handling. But the most important reason why people are comfortable and fast on Cervélos is that they fit properly.

Cervélo geometry offers two large benefits:

1) It puts the handlebars and saddle in the right position relative to the bottom bracket very easily in its standard set-up, making it easy to find a fast and comfortable position.
2) It offers a very wide range of positioning option thanks to the seatpost design and the different headtube lengths between the P1/P2 and the P3/P4. This allows our customers with a not-so-standard fit to take advantage of Cervélo’s superb aerodynamic and handling performance without any need to go custom.


Fonte: http://www.cervelo.com/bikes.aspx?bike=P42009