Cannondale unveils redesigned F-Si hardtail and radical Lefty Ocho suspension fork

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Who says high-end cross-country hardtails are dead? While lightweight full-suspension rigs are becoming more common on the World Cup circuit, they still can’t match a good hardtail for pure climbing speed, and Cannondale has just announced the second generation of its F-Si carbon thoroughbred.

Claimed weight on the top-end Hi-Mod version drops to a staggering 900g — 80g lighter than its predecessor — while the standard-modulus version is still just 1,100g for a medium size. The new F-Si is supposedly more durable, too, and now uses proportional tubing diameters for a more consistent ride quality across the size range. The seatstays have also gotten smaller, the chainstays are now more tapered, and the newly internal seatpost binder creates longer effective seatpost extensions for a given saddle height, all of which promise a smoother ride as well (for a hardtail, that is). Cannondale has even gone with a road-specific flat-mount rear disc-brake caliper so the seatstay has more freedom to move.

Carrying over is Cannondale’s unusual Ai asymmetric frame design, which offsets the chainring and the entire Boost 148 rear wheel 3mm to the driveside. According to Cannondale, this allows the frame to fit tires up to 2.35″-wide while still maintaining ultra-short 427mm chainstays — 3mm shorter than Specialized’s latest Epic Hardtail. The proprietary layout will invariably give some people fits, but the design is at least compatible with most standard 148mm-wide Boost rear wheels, and the readjusted dish will actually make for more symmetrical spoke angles.

Frame geometry has been more drastically changed, with longer front-centers and slacker head tube angles for more confident high-speed descending, while increased fork offsets keep the trail dimensions reasonable to maintain good low-speed agility — not unlike what has long been happening with trail and enduro bikes in recent years.

Fork travel is pegged at an XC-friendly 100mm courtesy of Cannondale’s radical new Lefty Ocho fork, which uses the same unusual single-sided design of other Leftys, but now sports a single crown. Cannondale hasn’t gone after the lightweight title with the Lefty Ocho, and indeed, at 1,446g for the carbon version, and 1,735g for the aluminum one, it’s at least 100g or so heavier than a RockShox SID World Cup or Fox 32 Step-Cast. Instead, the Lefty Ocho supposedly offers superior fore-aft and lateral rigidity despite the missing leg, along with the much-improved small-bump sensitivity that comes with the fork’s three-sided needle-bearing internal design in lieu of conventional solid bushings.

Inside the fork is a new OppO air spring with self-adjusting positive and negative chambers for a more supple feel and easier setup, and adjustable air volume for tunable spring rate progression. Nestled inline with the OppO is a new Chamber oil damper, with adjustable low-speed compression and rebound adjustments, plus a remote lockout. Easing the hassle of initial setup are printed-on air pressure recommendations and sag markers on the back of the plastic stanchion guard.

A new quick-release disc-brake mount will make it easier to get the front wheel off than before, too, and the F-Si’s rear dropouts switch to Mavic’s SpeedRelease design for faster wheel changes back there, too.

Cannondale will offer the new F-Si in seven complete builds, ranging from US$2,200 to US$9,000, and more detailed information can be found at We’ve got a test sample inbound, so stay tuned for an in-depth review.

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