I’ve always had a soft spot for Cannondale. The first “real” bike I purchased in college was a Cannondale CAAD9, and I’ve owned several more Cannondale bikes in the last 15 years. Yeah, Cannondale bikes can sometimes be super weird, but sometimes, weird actually works. That’s exactly how I feel about the final generation of the Cannondale F-Si and its Lefty Ocho fork.
In 2019, Cannondale released special F-Si “Throwback” frames with retro paint jobs harkening back to the legendary Volvo Cannondale race team of the 90s. I loved these Throwback frames so much that I actually bought one for myself. Now, years later, I still think that the F-Si is one of the best XC hardtails I’ve ridden, and that the Throwback Editions are among the most beautiful XC bikes ever made.
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The Cannondale F-Si: For Those With Serious Issues
I love this ad photo for the F-Si. Not only is it goofy, but it features Nick Cai, who is actually responsible for a lot of the design work you see on the TPC website!
It’s not necessarily official, but F-Si supposedly stands for: “For those with serious issues.” It’s a joke, but it gets to the core of what the F-Si is all about. Many XC racers love to obsess over having the lightest and most efficient race bike possible (I’m one of them). For many XC courses, you can’t beat the weight and efficiency of a good carbon hardtail like the F-Si.
Manuel Fumic raced World Cup XCOs on the F-Si Throwback Edition. Photo: Cannondale.
When the last version of the F-Si was released in 2018, the top-spec Hi-Mod frame had a claimed weight of just 900 grams, making it the lightest mountain bike frame Cannondale had ever made. Of course, XC nerds will know that the Specialized S-Works Epic Hardtail frame that came out in 2020 is lighter (790 grams), but the F-Si is still no pig, especially for a frame designed to handle the rigors of World Cup-level XC racing.
The example I'm featuring today is an X-Large, and admittedly, it has a pretty unspectacular build with a SRAM GX Eagle drivetrain, SUNringle alloy wheels, and an alloy bar, stem, and seatpost. But it still comes in at a super respectable 22 pounds 11 ounces.
My personal F-Si was a medium frame with SRAM XX1 Eagle, Hollowgram 25 carbon wheels, and a 120mm KS Lev Ci dropper post. It was 21.5 pounds with pedals and cages installed.
But the F-Si wasn’t just light. What really impressed me was the amazing combination of stiffness, compliance, and handling that it possessed. The lateral stiffness was extremely good and it was paired with Cannondale’s Ai-offset rear end, which created a stiffer rear wheel by allowing even spoke angles and tension.
When you hammered on the pedals, the response felt instant, launching the bike forward without wasting a single watt. It felt so efficient and fast that it actually convinced me to trade in my old titanium gravel bike for a more modern carbon bike because I wanted something that had the same impressive pop.
Despite the stiffness, however, the rear end never felt punishing. The thin seat stays and tapered chainstays did a good job smoothing out vibrations and impacts. I regularly rode the F-Si down super rocky trails and could comfortably stay in the saddle on many rough climbs.
While the geometry isn’t progressive by current standards (it had a 69-degree head angle and the reach is quite short), it was exactly what I wanted in a quick and agile XC bike. I rode my medium F-Si with 760mm bars, a 60mm stem, and a dropper, and I felt like I could absolutely shred (relative to XC hardtails) on this bike. However, the biggest reason the F-Si inspired so direct and confidence-inspiring was probably the fork.
The Lefty Ocho Carbon Fork
Of course, we can’t talk about the F-Si without touching on the bike’s party piece: the Lefty Ocho. The single-sided Lefty fork is probably the most iconic Cannondale product ever, and its divisive looks have inspired more trailside questions, comments, and jokes than any other piece of gear I’ve ever ridden.
I won’t dive too deep into all the tech behind the Lefty (I have a long post explaining Lefty forks if you want all the nerdy details) but I’ll cover the basics. Many riders think that the intention behind the single-sided design is to save weight, but that’s actually not the ultimate goal. At 1,446 grams, it’s comparable to the Fox 32 Step-Cast (1,443 grams) and heavier than the RockShox SID SL Ultimate (1,352 grams).
The Lefty has two main advantages over its competitors: greater rigidity and lower stiction. There are a couple of reasons for this. First, the fork leg is upside down, meaning the stanchion is at the bottom, and the fork upper, which is significantly thicker and stiffer, is mounted to the bike at the head tube where the forces are the highest and stiffness matters most.
To keep the single stanchion in place, it’s “keyed.” While the stanchion looks round, inside the upper, it actually has three flat sides that prevent it from spinning. This keyed shape also provides greater fore-aft and torsional stiffness than a round stanchion of the same travel and weight.
Strips of needle bearings move on the flat sides of the stanchion. In the Lefty Ocho, the three-sided bearing strip is called the "Delta Cage." Photo: Cannondale.
Extra stiffness reduces fork stiction, making Lefties feel more plush. But the thing that really takes the plushness to the next level is the use of needle bearings instead of traditional bushings. Bushings have more stiction, or static friction, that needs to be overcome before the fork moves into its travel. Compared to bushings, needle bearings feel nearly frictionless and allow the Lefty to quickly and easily move into its travel.
So while the Lefty Ocho weighs around the same as other top XC forks, it’s nowhere near as spindly. To me, the rigidity makes it feel and handle more like a stiffer Fox 34 or RockShox Pike, and I feel like this stiffness allows me to push it much harder. The super low stiction keeps things comfortable on rough terrain and helps traction in fast and loose situations.
So what are the downsides? The biggest one is serviceability. Servicing or rebuilding a Lefty usually requires a Cannondale dealer or approved service center (we service Lefty forks at TPC!) which can be expensive and annoying.
Because Lefties are single-sided, they also require a front wheel built with a proprietary Lefty-compatible front hub. This adds complication if you ever need a spare or want to upgrade. Then there’s perhaps the biggest downside of them all — enduring the endless jokes other riders like to make about “missing half your fork.”
The Throwback Paint Hits Different
The F-Si was one of my dream bikes for a long time. It all started with the classic video of Peter Sagan riding with Olympic Bronze medalist Marco Fontana, which perfectly captured how I dreamed my own riding could look:
Then, when Cannondale released the F-Si Throwback Editions in 2019. I instantly knew that it was the perfect bike for me because I had grown up idolizing Tinker Juarez in the late 90s.
Without a doubt, the 90s were the heyday of American mountain biking, with legends like Tinker, John Tomac, and Ned Overend duking it out at the NORBA national races. Tinker was always my favorite rider. To me, as a person of color competing and winning in a predominantly white sport, he was a true pioneer.
When you watched old races, it was impossible to miss the curly mess of dreadlocks flowing out from under his helmet or the dark tanned skin stretched over his skinny sinewy legs. And with a brilliant nickname like Tinker, he felt like a comic book superhero come to life.
I'm such a fanboy, when I got my F-Si Throwback Edition, I immediately ordered a set of Tinker's signature ODI Dread Lock grips, just to add some extra mojo.
Volvo Cannondale. Photo: Zapata Espinoza
In the the 90s, Tinker raced for the biggest and baddest team of the era, Volvo Cannondale, which competed from 1994-2002 and featured legends and world champions like Alison Sydor, Missy Giove, and Myles Rockwell.
The F-Si Throwback Edition framesets and the vintage Cannondale F frames they are based on. Check out those Headshok forks!
The 2019 F-Si Throwback Edition was released to celebrate the 25th anniversary of when Volvo Cannondale was founded. It was available as a frameset only, with a color-matched Lefty Ocho Carbon fork. It came in two color options: Viper Red, the Volvo Cannondale colors from 1994-1997, and Team Blue Gloss, which was used from 1998-2002.
For the logos and headbadges, the frames used vintage Cannondale fonts and designs. The Lefty Ocho fork even features the old Headshok logo, a call back to the original Headshok fork which was the progenitor of the Lefty.
To me, four years after it was released, the F-Si Throwback Edition is still one of the best-looking XC bikes ever made. It was a perfect combo of nostalgia and modern perfromance. The retro colorways perfectly complemented the traditional diamond frame shape and round tubes, and it all flows beautifully into the color-matched Lefty Ocho. I don’t think any mountain bike I’ve ever owned has received so many compliments out on the trail.
Sadly, I did sell my F-Si Throwback Edition in 2022 to switch to a Specialized Epic Evo. Since Throwback Edition was only offered in 2019, and it was sold in limited quantities, it will become harder to find over time. Though I do love my current XC bike, I still feel a bit of regret. I might end up always looking back at that beautiful bike, and thinking of it as the one that I let get away.
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