New Gear: Cannondale's Fast XC 26ers and 29ers

Published September 2, 2010 05:00PM

When you ride a super stiff and responsive full-suspension cross-country bike that weighs under 19 pounds, even in an XL size, and has 80mm of rear travel, you can get pretty spoiled. And that’s exactly what the 2011 Scalpel Ultimate did — spoil me riding it on the amazing Mid Mountain Trail at Park City, Utah.

The trail traverses more than 40km of wonderful, flowing singletrack hovering around 8,000 feet of altitude from the mid-mountain Silver Lake Village at upscale Deer Valley Resort across Park City Mountain Resort and The Canyons resort. Considering the scenery, almost any bike would be fun on this trail. But it’s a blast on a bike like the Scalple Ultimate that is light, torsionally stiff, remotely locks out front and rear, gets up the climbs quickly and negotiates the twists with aplomb.

Strong Pedigree

The Scalpel’s racing pedigree is exhaustive, with four world championships and two World Cup overall titles to its name, along with countless World Cup and national championship victories to boot. It has no main pivot near the bottom bracket, and it achieves its three inches of travel through the flexing of its horizontally-flattened carbon chainstays.

Scalpels used to have 100mm of travel, but Cannondale decided that was overkill for its purposes as a race bike. Along with the travel reduction came an increase in lateral rigidity through changes in design and layup of the chainstays.

Like on the SuperSix road bike, the chainstays and bottom bracket shell (73mm-wide BB30) are molded in a single piece. But the front end is built in a tube-to-tube construction. The Scalpel no longer has a chainstay bridge or an aluminum bottom bracket shell, and the old option of an aluminum front triangle no longer exists, either.

The new Scalpel has no rider weight limit, even though all of the chainstays and seatstays are the same on bikes of all sizes. However, the layup of the front triangle is size-specific, and Cannondale claims to have tested this bike just as hard in its state-of-the-art test facility as its long-travel bikes. Company tests, as well as those by an independent test lab, are claimed to have demonstrated that this frame has by far the highest stiffness-to-weight ratio of any full-suspension frame. Cannondale further claims that it is lighter than any other full-suspension frame, and when compared without the shock is more than 600 grams lighter than its lightest competitor.

The front section of the top tube is lined up directly with the rear shock to keep the carbon fibers in only tension and compression, and extra layers are concentrated at the bend in the tube where the shock mounts. The 60mm-diameter down tube and oversized head tube area grants lots of stiffness, as does the flared-out seat tube, which is afforded that shape by use of a direct-mount front derailleur attachment. The double-sided rear derailleur hanger sandwiches the dropout and is far stiffer than a standard single-sided one.

Flash and Flash 29

Weighing in at 950 grams for the Flash (26er) and 1050 grams for the Flash 29, this carbon hardtail has been making a mark in races for some time. It is made of the same military-technology ballistic carbon as the new Jekyll. Its wide top tube meeting the 1.5-inch headset blends straight into the seatstays for lateral rigidity. The SAVE rear stays have a flattened sections to allow flex, which Cannondale measures at 7mm of vertical travel. Furthermore, it claims that the flattened SAVE section of the seatpost provides 40mm of vertical travel!

The Flash 29 comes equipped with a Lefty fork designed for 26ers with 120mm of travel. However, its travel has been limited to 80mm to prevent the tire from crashing into the crown.

Lefty

Still the only brand with a single-sided suspension fork, Cannondale has remained committed to the Lefty throughout a number of rough patches for the company as a whole. Lefty forks are a mainstay of its high-end short- to intermediate-travel bikes.

The Lefty offers some features that two-legged forks cannot match; Cannondale can (and does) argue that the Lefty is stronger, stiffer, smoother and lighter than any other fork. Indeed, the heaviest Lefty is lighter than any other company’s lightest cross-country racing fork.

Smoothness of movement is probably unmatched in the industry as well. And like on a motorcycle fork (or on a human body or body of any other animal or insect), it is designed with the fattest part being at the center of force, while the appendages become progressively skinnier the farther they are from the body. This is the opposite of most bicycle suspension forks. And it’s the only fork that makes possible Jeremiah Bishop’s trash can for energy bar wrappers!

The Lefty’s sliding inner fork leg rides on 88 internal needle bearings, and it has no bushings to wear out like most forks or suspension seatposts. These bearings combined with not having a second leg means that there is no binding under side loads, and Cannondale has a portable demo station that provides a tactile experience of this. The demo stand has unbranded two-legged forks of competitors and Lefty forks held rigidly horizontally by their steering tubes with the spring and damping removed.

When pushing straight on the fork dropouts, all of the forks slide smoothly, although none moreso than the Lefty. But when leaning down on the horizontal fork, thus putting a force perpendicular to the legs on it while also pushing in the direction to compress it, the two-legged forks bind up and are very resistant to moving, while the Lefty just keeps moving smoothly.

This can be a real safety feature if a rider gets caught overcooking a turn under full braking. The Lefty can still be active and prevent the washout that most certainly would occur in this instance with a fork fully bound-up from the braking and side-loading.

The straight head tube with pressed-in 1.5-inch headset bearings that Cannondale pioneered with the Headshok has become an industry standard, and it affords the rigidity that the Lefty depends on.

Leftys for the Scalpel and Flash offer 100mm of travel and are fully integrated with the SRAM XLoc hydraulic bar-mount lockout button. The upper-end Lefty Speed Carbon model has a carbon upper (outer) leg, and the aluminum lower leg (and upper leg on the Lefty Speed) is made of 3D forged aluminum, rather than the multiple pieces of the past. Similarly, the 2011 one-piece OPI stem/head tube is forged in a single piece.

With all of this metal forming, the Lefty stem/head tube system went from seven parts down to an impressive three parts. The new stem/steerer has adjustable stem height via threads atop the steerer, which the user rotates with a bottom-bracket-cup wrench after loosening the fork clamps. And it is with this System Integration, as Cannondale calls it, that it claims the 600-gram weight advantage over its lightest competitors when comparing the frame, fork, crank and stem.

Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn.