World's most aero frameset
What the P3 was to the world of individual cycling events against the clock (contre le montre, as the French say) was nothing short of a revolution. The P3 took what the extraordinary and model-range-defining Cervelo P2 did to a previously almost backwards industry and went further than anyone could have foreseen. Then, while the rest of the industry still labored to catch up with the P2, Cervelo struck hard at the competition and surged forward with the P3C. In no uncertain terms, the P3C became the singular defining (UCI legal) time trial / triathlon frameset of all time.
In the 1970's Triumph developed the TR7 whose wedge-shaped body was called "the shape of things to come." It's too bad the TR7, a design that did come, but also went, secured forever that catchy phrase for if there were any justice in the world of advertizing no phrase would have been more readily attributed to any product than Cervelo's P3C. The P3C has been copied, emulated, and duplicated so much that, for the untrained eye, it's nearly impossible to tell which bikes among the professional peloton are Cervelo's and which are, well, everyone else's.
But if imitation is a form of flattery, then well flattered the P3C is. The P3C was not just a stunning engineering and aesthetic feat. Pick up a P3C and then pick up one of its knock-off analogues and even the uninitiated will instantly notice one thing: the copies are heavier. A lot heavier. That the brains at Cervelo were able to create the aspect ratios they did on the P3C's narrow and super-aero tube sections and still maintain low weight, high strength and phenomenal power transfer is nothing short of a miracle. Those who have tried to copy Cervelo come up short in this respect: their bikes are either aero, but substantially heavier, or they're just plain not aero. If they do get them light and aero, they don't transfer power because they're simply not stiff enough.
So, again, the world chases Cervelo. And while they do, and try to get shapes as like the P3C as possible (it had, after all, the lowest coefficient of drag of any available TT frameset), Cervelo strikes again with their latest incarnation of the world's most superior aerodynamic bike frame shape: the highly anticipated and hotly desired Cervelo P4!
Cervelo spent over one million dollars in wind-tunnel time alone in the development of the P4. In addition to this, they used new fluid dynamics computer modeling so sophisticated it required 5 computers working 24/7 to masterfully design tube shapes so aerodynamic that the new P4 creates over 100 grams less drag that the next fastest TT bike in the pro peloton (and a whopping 60 grams less than the P3C!). And if that means little to you, this will mean a lot to you TTers and triathletes: 20 grams of drag reduction means 10 seconds at 25 mph over 40 kilometers. In short: the P4 is 50 seconds faster than the next fastest aero frameset over 40 km at a very manageable 25 mph, and 30 seconds faster than the P3C!
So where were the improvements made? Primarily, Cervelo was able to incrementally reduced drag in six areas: (1) fork, (2) head tube, (3) front wheel positioning, (4) rear stays, (5) rear brake placement, and (6) refinement of the P3C's tube shapes.
While Cervelo played with various (1) fork configurations, including the popular "bi-plane" design, their engineers found that small alterations in the shape of the existing 3T Funda fork, most notably at (2) the head tube junction, made the biggest improvements. In fact, despite the theoretical advantages of the bi-plane fork design, Cervelo learned that this design provides no real advantage, and in some cases creates additional drag, unless the bike is moving at speeds far exceeding those possible on a human-propelled bicycle. Cervelo also did not integrate the brake calipers into the fork as so many had speculated (although this does appear at the back of the bike (5)), and claims that the structural integrity of the fork could not be engineered with this kind of braking mechanism.
The position of the front wheel (3) has been moved closer to the down tube to create a more uniform airfoil configuration from the wheel through the main triangle. Again, Cervelo experimented with down tube cut-outs to neatly "tuck" the front wheel, but found that, while this provides some aerodynamic advantage if 0-degree wind angles prevail whilst the cyclist is traveling in a dead-straight line, it nevertheless provides a virtual wall for on-coming air at wind angles greater than 0-degrees (namely, 90% of real world conditions) or when the front wheel is being adjusted or steered (again, about 90% of the time).
The (4) rear seat stays have also been considerably lowered on the down tube to reduce drag created by turbulence behind the rider's body, and, in addition, the flair of both the seat stays and chain stays has been improved to allow "trapped" air to exhaust from the bike more freely so as to not create additional turbulence around the rear wheel. The result of this is that the new Cervelo P4 will accommodate standard lenticular discs and the new Zipp Sub-9 disc, but the tolerances are extremely tight!
As Phil White is very fond of saying, there are two things crucial for making an object aerodynamically efficient: shape and frontal area. While many bike manufacturers are placing brake calipers in sundry locations to ostensibly hide them from the wind (i.e., reduce frontal area), the benefit to date has proven lackluster. The reason for this is that, on current designs anyway, the brakes' calipers are not hidden: they're just relocated. Witness the rear brake caliper placement on any of the new time trial designs: it's certainly hidden to the eye, but it's hardly hidden from the wind. The same is true of front calipers mounted behind the fork: the body of caliper may be out of sight to the wind, but the outermost ends of the calipers still create as much drag as if they were front mounted.
Cervelo's new rear brake design in entirely novel: using a proprietary braking system, Cervelo has actually recessed individual calipers into the chain stays behind the bottom bracket shell. To smooth airflow across the bottom of the bike and to effectively hide the brake calipers, Cervelo ingeniously created a removable carbon cover for the braking mechanism. Unlike designs with rearward braking systems that are nearly impossible to work on, Cervelo's clever concept makes your local mechanic's life much, much easier.
At the end of the day, Gerard Vroomen's aphorism shines: "It's easy to create something new; it's very hard to create something better." Is the P4 better than the P3? The data bears out that it creates about 100 grams less drag than the next best testing pro-peloton TT frameset; again, that's 50 seconds over 40 km at 25 mph. If your idea of a "better" TT bike is one which goes faster than the competition, then yes, the P4 is substantially better. The new P4 frameset will SRP at $4,800. Initial production runs will be for the size 54 only, and these should see delivery during first quarter of 2009. Additional sizes will trickle into stores throughout 2009.