Competitive Cyclist

CERVÉLO R5CA

Originally referred to as "Project California", the frameset now known as the Cervélo R5ca is laid up by hand then molded at Cervélo's test lab in California. In some respects, this is the old way of doing things, where the frame is built by the designer. The 21st-century twist is that the designers are a team of engineers and the framebuilding consists of using the latest space-age technology and techniques to turn some 350 pre-preg carbon fiber sheets into frame gold.

The result is a frame that's ridiculously light (700g claimed weight for size 56cm) yet ridiculously stiff (22-39% stiffer depending on the area of the frame compared to the baseline of the R3) and more than strong enough to handle racing on pavé (higher impact resistance) and should fit just about everybody well (new sizing). As you know, such a boast means nothing if the bike doesn't ride well and isn't durable enough to stand up to the rigors of racing. So we'll point out that this frame was put through its paces by the Cervélo Test Team, first in training and then at the 2010 Tour of California. Think of it as light enough for Carlos Sastre and stiff enough for Thor Hushovd and comfortable enough for Heinrich Haussler to ride his in an all-day solo breakaway and fits all equally well. The one difference is that these guys need to race with solid steel rods inserted into the seat tube to meet the UCI minimum weight requirements, so the design advances which save weight aren’t for them. Since you’re not riding the ProTour, you don't have to suffer that fate. Though the R5ca is designed to perform for them, it's intended to be ridden by you.

In order to make "Project California" a reality, Cervélo engaged an impressive braintrust. Leading the effort is Don Guichard, their director of technology and manufacturing. He's been working in composites for over 20 years, including a stint developing the GT Superbike II for the 1996 US Olympic Team and several other rocket scientist types who ride and love bicycles. That's one end of the braintrust; they work at the Project California facility. Making communication between the engineers at Project California and the Cervélo Test team happen is Damon Rinard, Cervélo's race engineer. He's also a bike geek extraordinaire, who before hooking up with Cervélo, was working in the aviation industry. The other is the Cervélo Test Team, which first gets the bikes for training and evaluation, and when that's successful, they get them for racing and evaluation, for a feedback loop that is second to none. When the loop is all in agreement, Cervélo knows they have a great product.

Even though Cervélo uses molds for the frames, they broke the mold with the work that led up to the creation of the R5ca. There are plenty of computer modeling programs that inform bike design, but Cervélo decided to toss out old assumptions. For starters, they put strain gauges on a bike and rode it to see if they could learn more. Among other things, they found that there are much higher bending loads on the seat tube than is commonly assumed (they found that loads from a seated rider are more significant than standard frame torsion tests postulate). But that's just one of many valuable results. Possibly most importantly, they used the data gathered from their strain gauge bike to create more realistic tests to push any frame design up against, which resulted in new lay-up designs and creating more advanced tools to help make that lay-up a reality.

Project California has also resulted in a new kind of mold machining of frames. This results in Cervélo being able to fabricate more complex molds that can produce a more precise frame that needs less finish work. The simplicity here means less sanding of the frame that can result in a more reliable, stronger frame thanks to reducing the possibility of structural layers getting sanded off in the finishing process.

And for those who worry that carbon-fiber frames are great for riding but a tad delicate when crashed, the R5ca will surprise here as well. The frame exceeds European safety standards by a minimum of 20 percent. It also beats front-end impact standards by 150%. In terms of the fatigue life of the bottom bracket, Cervélo has designed the R5ca to exceed the fatigue baseline of their older designs by 150%. They do this by mixing plies of lower-modulus carbon-fiber with plies of higher-modulus carbon-fiber. High-modulus carbon-fiber makes for better copy, but the stuff is brittle, so mixing plies is the smart way to make the frame stronger.

Design and production details, that's like getting obsessed over engine internals, only the obsessive dig on it. Regardless of who you are, you should pay attention to the results of this work. For example, the seat and down tubes look off-center and the water bottle bolts look like they're mis-aligned. They're not. What you're seeing is a result of Cervélo optimizing the seat and down tubes to better resist bending forces. Likewise, the left side of the bottom bracket shell and the start of the left chain stay look larger and thicker than the right. It is. Since the right side of the bottom bracket and the right chainstay is limited by the drivetrain, Cervélo explored making the frame stiffer by making the left side of the frame larger. It worked. They also found that by placing very thin walls inside the frame tubes by the bottom bracket shell, walls called bulkheads, they could further stiffen the bottom bracket without adding weight. These design improvements wouldn't be possible without even more design work, particularly the new bottom bracket they've debuted with the R5ca, BBright. Basically, it's very similar to the Pressfit 30 standard and uses the Pressfit 30 oversize bearings on either side of the bottom bracket shell, but they found that if they extended the shell on the left by 11mm and changed the dimensions of the left crankarm a bit, the result is a stiffer, stronger, smoother-running bottom bracket with no increase in q-factor. They've also gotten their team component suppliers, SRAM and Rotor, behind this, as well as FSA and Zipp, all with dedicated cranks. Campagnolo supports it with an adapter for their Ultra-Torque cranks and the system also works with Shimano.

Rather than having to worry about finding cranks to meet this new standard, Cervélo supplies a set of BBright Rotor 3D 30 cranks and BBright bottom bracket with the R5ca frame and fork. They're very similar to the standard 3D cranks. The Trinity drilling is done from the spindle end of the crankarms and removes material to save weight, yet the design leaves the cranks plenty stiff. The 30mm hollow alloy spindle is permanently affixed to the left crankarm. The right crankarm has a splined interface and is affixed and removed by a self-extracting 8mm bolt. Sitting between the left arm and the BBright shell is a locking adjustment ring, very similar to what you find on Shimano XTR cranks, which you use to adjust the bearing preload once the cranks are properly torqued into place. Overall, the Rotor 3D 30 system saves you 30g over the "standard" 3D road crankset and bottom bracket. The crank is supplied with 53/39 round Rotor rings. However, if your preference is for 50/34 and/or Rotor's elliptical Q-rings, we're happy to make that change at no cost.

Cervélo doesn't include a seatpost with the R5ca frame, but they designed the frame to work with a 27.2mm zero-setback post like the team-issue 3T Dorico LTD seatpost. And this brings up another interesting advance Cervélo has initiated with Project California; they've slackened the seat tube angle slightly. While they certainly did lots of measuring of people and positions to come to this conclusion, they're advancing a theory that Keith Bontrager put forth years ago; seat angles don't matter so long as the cyclist can get in the right position relative to the bottom bracket. They expect just about everyone to fit this frame with a zero-setback post as they found that a 73-degree seat angle with a setback (or offset) post works for most everybody and simplifying the post to a zero-setback is another way to reduce system weight.

In rethinking the bike, Project California also addressed the fork and head tube juncture. While they found that the 1-1/8" diameter lower bearing is not quite stiff enough for the materials they're using, they also found that the 1.5" diameter lower is actually too stiff and transmits too much force to the frame, so they determined that 1-3/8" was the diameter that worked best with the needs of the frame and rider. So they chose the Cane Creek AER headset lower race, with a 1-3/8" lower bearing for the bottom half of the headset. To further reduce weight, the fork crown race is molded into the fork. For the upper race of the headset, they're forgoing a headset race entirely; in its stead, they've got a Teflon bushing between the head and steerer tubes. This kind of upper race is making inroads in frame design, and Cervélo is supporting it completely; they're stocking the bushings.

The fork is not built in-house. It's a Cervélo-designed FK 30 SL fork with carbon-fiber tips. The fork is designed to be laterally stiffer and more vertically compliant than the current team-standard 3T Funda Team carbon-fiber fork.

With Project California, Cervélo also decided to revisit frame-sizing conventions. Yes, describing a frame size by the length of the seat tube is fast-disappearing. But as many are finding out, using the virtual top tube length as the sizing convention also has limitations; it doesn't take into effect head tube height, which can affect position in a profound way. Cervélo has taken a good look at the sizing conventions and size runs of their older designs as well as some frames from other manufacturers to develop a more consistent sizing configuration. With the R5ca and other frames going forward, they want to use a measuring convention called "stack and reach." Stack is the distance from the centerline of the bottom bracket drawn vertically to the top of the centerline of the head tube. Reach is the horizontal distance drawn at a right angle from that line to the center of the head tube. Starting from the smallest size and working larger, each frame has a taller stack and longer reach, and these dimensions will progress in a linear fashion through the size run. This might seem elementary, but many manufacturers don't shorten the reach on their smallest sizes, they just steepen the seat tube angle. One result of this is that the R5ca won't have any women's-specific frames; this new sizing eliminates the need. Another is that people with long or short torsos relative to their height will have an easier time sizing. Another is that you'll have an easier time comparing one frame of one maker to another.

They also looked at all the little things on the frame and found ways to improve just about all of them. The dropouts are carbon fiber, with a newly-designed replaceable aluminum derailleur hanger that attaches via bolts from the inside of the right dropout, passing through the dropout stub and threads into the hanger itself. This results in a lighter dropout as well as a stronger grip on the hanger, and it's easier to replace. The front derailleur mounts on an aluminum mount that is bonded and riveted. The cable stops are carbon fiber and molded to the frame rather than riveted. The bottom bracket redesign gave Cervélo a reason to design their own bottom bracket cable guides for smother cable routing. Atop the seat tube is Cervélo's own aluminum seatpost collar with a titanium bolt and aluminum nut that goes over a unique three-slotted opening that eliminates the dreaded carbon-fiber seat post slip by evenly increasing pressure around the seat post rather than by pinching it in one spot.

 Share this Page

2011 Cervélo R5ca Pricing