Development Story: Cannondale's Wild New Single-Sided, Single-Crown XC Fork

The Ocho will be available to buy on its own at some point in the future, but not for the 2019 model year. That means that if you want an Ocho soon, you'll have to get yourself Cannondale's newest F-Si cross-country bike that it's bolted to the front of. I expect that to change in the future, of course. More travel isn't on the cards, either, at least not with the current package: ''With Ocho we wanted to make the best XC fork possible, and that meant focusing on 100mm of travel only,'' Greg Jakubek, Product Developer – Suspension and Components at Cannondale, explained. ''Longer travel is not compatible with this chassis. As for what we have cooking for the future, you’ll just have to wait and see.''



I spent a few days at Cannondale's Bethel, Connecticut, headquarters earlier this year to learn all about the Lefty Ocho and also to throw some tough questions at Jeremiah Boobar, the Director of Suspension Technology Components and the project leader for the new fork.


Fair enough, Jeremiah. But while I can see the benefit to not following the same path as everyone else, I'm also willing to bet that they'd sell a load more of their own bikes if they all came with traditional forks rather than the Leftys on the front of some models. ''I totally agree, there are a lot of traditional looking forks out there. But at Cannondale, we go really far to find unique ways to give riders true benefits out on the trail. And one thing that Lefty has done that no other fork has is being excellent in what we call loaded friction,'' Boobar explained. ''When the fork is seeing loads and starting to bend, the roller bearings inside keep it from having any friction whatsoever, whereas a traditional fork with its bushings starts to get bind-y and reduces that small bump feel.''

So it's not just to be different for different's sake, he's implying, although being an oddball certainly does also have its benefits, too.




Boobar continued: ''You take a super lightweight carbon hardtail, and you could be the lightest one out there, but you put the same fork on there and it isn't really special, you know what I mean? And you put the same derailleurs on a bike; you put the same cranks on a bike... You see more and more of that, but by being unique and offering something else, it really attracts people who are looking to be their own person out there.''

''And once they understand the product, they understand that it's more than being unique and different from all your friends. It's about genuine performance and being able to ride faster out on the trail.''




The simple fact of the matter is that Cannondale's suspension division is never going to trouble the likes of Fox and RockShox when it comes to aftermarket sales or, obviously, OE spec, but that very fact also frees Cannondale up to be, well, Cannondale. ''Just like somebody loves one suspension company or another, and you're not going to convince them to go the other way. We realize that but we're also not trying to be one of the major players out there. We're trying to be Cannondale, and we're trying to be true to who we are, and we believe that our performance is going to speak for itself.''



But why a single-crown, especially after nearly twenty years of dual-crown Leftys? Most of their reasoning comes down to compatibility: The dual-crown Lefty 2.0, the Ocho's predecessor, has its crowns integrated into the upper tube in the name of weight savings and rigidity, but that also means that a bike's headtube needs to be precisely the right length for the Lefty 2.0 to fit. Even a few millimeters too long or too short means that it's a no-go.


So, can you - and do you want to - understand a single-crown, single-sided cross-country fork? It's wild looking, no doubt about that, but Boobar stressed that the Ocho's appearance is only part of the story: ''It isn't just that aesthetic. Once people get out on the Ocho, they're really going to notice the benefits out on the trail,'' he said. The fork's design, with its roller bearings and three-sided stanchion, is said to provide the advantage of no binding and exceptional rigidity, and the byproduct of the layout is that it allows Cannondale to go with the single-sided, single-crown design that's sure to turn a lot of heads and blow a few minds.




The Lefty Ocho has been under an incredible amount of secrecy during its development, with only a handful of Cannondale employees even knowing about the project. Despite the classified work being done behind closed doors, Cannondale gave us essentially unrestricted access to the Ocho, the team behind its evolution, and many of the challenges they faced while working to bring the fork to life.

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Developing the Single-Sided, Single-Crown Chassis



The Ocho doesn't share a single component with the Lefty 2.0 internally or externally, and both the carbon and aluminum models have been designed as a single-crown fork right from the get-go. And it turns out that Cannondale was experimenting with a single-crown version of the Lefty back in 1995, first by taking one of those 2.0 forks, lopping the top off of it, and manufacturing a hollow crown using the same method as they do for their lightweight and stiff Si (System Integration) cranks.


A big reason for the Ocho's low weight is its all-new stanchion and lower tube design that Extance says is the lightest that Cannondale has ever designed. If you were to strip the Ocho down, you'd find that the stanchion is three-sided rather than four-sided like on all previous Lefty forks, and its three strips of roller bearings are actually manufactured as a single, flat piece before being rolled up and clipped together to fit inside the fork. If you've ever worked on a Lefty or Head Shok, you'll know that this captured, one-piece roller bearing setup will make the fork infinitely easier to work on.

The three-sided stanchion is said to provide a few advantages over the old four-sided tube; three strips of roller bearings weigh less than four strips, of course, and there's less friction in the system for the same reason. Also, Cannondale says that it allows the stanchion to self-center, which make for more consistent action from fork to fork; a four-sided tube might have two facing sides that have tighter tolerances than the others.




The single-sided, single-crown design is obviously the big talking point here, but there's another detail that's sure to raise some eyebrows: The Ocho has a (kinda) quick-release brake mount that lets you remove the caliper by turning a single, captured 5mm Hex bolt 180-degrees.

There's no backing any bolts out only for them to roll away into the ether, and the slotted mount found on older Leftys that required loosening two bolts so you could slide the mount up to get it off the fork and allow you to remove the wheel is nowhere to be seen.





With only a single fork leg, you obviously don't need to take the wheel off to fix a puncture, but the easily removable brake mount lets riders remove the wheel off if they need to put the bike inside a car or do some mechanical work, all without needing to set up the front caliper from scratch afterward. Braking actually pushes the mount onto the fork leg, too, so there shouldn't be any possible way for it to come off. Pretty clever.

The design has two main components that make it possible: The cam itself that grabs onto a small steel post on the fork lower, and two cone-shaped extensions that ensure perfect alignment every time you re-install the mount. The 5mm hex is captured on the mount itself, with the locked and unlocked positions being clearly labeled; turning the bolt to the unlocked position rotates the cam and releases the mount, and doing the opposite locks it back down onto the fork again.





Neat, but it's not exactly like the Ocho needed something else to set it apart from the crowd, is it? Of course not, but Extance was quick to point out that the Ocho's removable brake mount has passed testing with flying colors, and the production version is as robust as anything else out there. It's also a component that saw a load of development, with many different versions being trialed, some of which even employed a locking button, before Cannondale settled on a simpler, easier to use, and more durable design. You can see it in action in the video below.

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Inside the Ocho's Chamber Damper

While the Ocho's platform is wilder than anything we've seen since, well, the Lefty 2.0 that came before it, Cannondale took the opposite approach when they designed the fork's internals. That's a very good thing, too, because, after eighteen years of sub-par damping inside previous Lefty models, this one has to be a home run. In the past, Cannondale has either made their own dampers (that weren't great) or licensed technology from other suspension companies.

The latter approach was certainly smarter but, even then, the Lefty was never on-par with whatever fork was best in class at the time.




So with the Ocho, Cannondale did two vitally important things: One, they decided to design and build a closed damper that uses a proven layout; second, they brought in Jeremiah Boobar, one of the main guys behind the Charger damper that raised the bar when it was introduced in the Pike a handful of years ago. It's no surprise that most fork manufacturers have since followed the same closed damper route, and it's even less of a surprise that Cannondale is doing the same.


''Some of the ways we got around the space constraint is that we minimized the height of everything in the damper circuit and, separately, everything in the air spring circuit.''

Job done, right? Well, it turned out to be much more involved than just shrinking everything down by as much as possible. The story of the damper's internal floating piston, usually an uninteresting and relatively simple component, highlights the lengths that Cannondale had to go to.




First, a quick refresher: The IFP is a piston that has the damping oil on one side and gas (usually air these days) on the other. There is essentially no air in the damper, so for the damper rod to compress into the cartridge, the IFP moves and compresses the gas behind it. Not only does this allow for fluid displacement, but the gas behind the IFP also provides important back-pressure to help keep the damping oil from cavitating. This is all proven stuff that's been around for years on all sorts of vehicles, both gas and human-powered.

Proven it may be, but Slaw and his team had quite the time getting the Ocho's low-profile IFP to work as required. ''The reason it has to be that way is just to fit our space constraints,'' he said of what looks a lot like a plastic top hat.




The IFP grew during testing as the larger the diameter, the less it needed to move up to allow for the same displacement. The relatively massive IFP can be so big because the upper portion of both the alloy and carbon Lefty Ochos are huge, so the room was there. Slaw used it, too, and the IFP in the Ocho's production damper has roughly a 10:1 ratio, meaning that it moves around just 1mm for every 10mm for shaft movement.

Long before anything was locked-in for production, Slaw and his team discovered that the large diameter of the IFP, along with the low height requirement, was allowing it to rock ever so slightly under heavy loads.


''There is no way we could have ended up with the same stack [height] using aluminum as we did by using Delrin,'' Slaw replied when I asked why they didn't go with metal.

The final product looks a lot like any other high-end fork damper, and that's exactly what Cannondale was going for. For a brand that's never shied away from doing things their own damn way, the damper was one area where it pays to not think too far outside the box. The way many riders look at cross-country riding and racing is changing, however, with more and more people pushing short-travel bikes harder than ever before, which surely means that many of those same riders are expecting more from their damper than someone who might not run a dropper post on their cross-country bike.




''It's really hard to balance that,'' Slaw said of the task of trying to keep everyone happy. ''I think, kind of to our advantage, most of us here ride a lot of trail bikes and then downhill on the weekends, so we understand that low-speed performance that you're looking for. We did our best to put that more in the max range and have it super compliant at anything below that.''

So while there's no three-position compression switch for on-the-fly tinkering, the Ocho's crown-mounted low-speed compression dial should provide all the range required, Slaw says. ''Between what I think is optimal for a dry day, a pumpy track, somewhere where you can really pump and generate a lot of speed through your progression; that rider should be able to find something they're interested in. Then, also, a marathon rider, or someone who's spending a ridiculous amount of time in the saddle, maybe even sloppy conditions where traction is your main concern; you can dial that low-speed [compression] back and have a super supple, well-tracking fork for that day.''
While the Ocho's low-speed compression is tuneable incrementally rather than a three-position switch, it does come with a handlebar mounted lockout remote... Whether you want it or not, at least right now. It's a two-lever RockShox unit meant to mount below the handlebar, and you can't remove it as it stands right now. So, if your bike already has a remote to control the shock, and a dropper post remote, you might end up looking for room to add a third lever if you end up considering the Ocho.




Given that it's a pure cross-country fork with race-focused intentions, the lockout makes complete sense. ''Damping was a huge priority for this project, and we felt the only way to get the right performance, the right quality that we wanted, as well as the lockout performance we wanted, was to split it up into two pistons.'' Compression damping is done on what Cannondale calls the 'Performance Piston,' which is where you'll find the shim stack and check valve, of course, while the lockout piston sits above all that and has two jobs to do. First, it needs to firm the fork up substantially while also providing a blow-off for when I forget to unlock my fork because I'm busy suffering an anaerobic death during a race; second, it needs to allow for maximum oil flow when it's not locked out, which explains the large ports machined into it.

The Ocho's air-spring chamber sits below the damper with a Schrader valve down by the axle and a self-adjusting negative spring. Progression is tuned by adding or removing volume-reducing tokens that go on over the damper rod, so you can easily tune how much ramp-up it has.

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The Little Things

While the Ocho is sure to make jaws drop from afar, a closer look reveals a few interesting details as well, including a well thought out brake hose guide that consists of three pieces. First, there's the slotted cable guide on the upper tube that's split to wrap around the hose before being locked into its home on the leg. Just below that is a stiff shroud that clips onto the hose, and it's just the right length to slot into the upper guide and rest in a groove at the top of the fork guard. The guard itself is the last component of the system; a small clamp on the backside of the guard grips the hose firmly.





If you think that setup sounds a lot like what you'd find on an inverted motorcycle fork, you'd be bang-on. It lets the fork go through its travel and displaces the hose above the slotted guide, thereby keeping it far away from your spokes and the Ocho's lone stanchion tube. You can see how the top guide works in the video below.





The sturdy looking guard itself is also quite the thing, too. It's carbon because why not, and its shape means that it's rigid to keep it from rattling around against the fork regardless of how rough the trail is.

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As wild as the Ocho looks, there are a few rather simple questions to answer here: Is the fork's three-sided stanchion and single-sided chassis torsionally rigid enough? And is the fork's air-spring and damper leaps and bounds ahead of what Cannondale has offered in the past? To find out, I've had a Lefty Ocho mounted to the front of Santa Cruz's 100mm-travel Blur for the last few months, but given that the single-crown, single-sided fork sticks out like a cross-country bandit at Crankworx, I've had to be a bit sneaky about it.

Cannondale supplied a trick, 3D-printed extension that clamped under the stem and extended down to the top of the Ocho, an add-on that, at least from a few feet away, had the Ocho looking very much like a run of the mill Lefty 2.0. It even had dials at the top that you could turn; they were obviously not attached to anything, but the stealth setup tricked more than a few passerbys.




Disguises aside, I'm guessing that you want to know how the Ocho performs. A long term review is almost complete, but for now, I can tell you that yes, the Ocho is more than torsionally rigid enough, and comparable, if a smidge stiffer, than the likes of the 32 Step Cast and the SID World Cup. I'll also tell you that the new Chamber damper is as good as anything else on the market right now, which means that it's light-years ahead of anything Cannondale has used in the past. This is also underlined by the fact that the Lefty 2.0 will be put out to pasture after this model year, with it being replaced in the catalog by the Ocho.

I'm currently putting together my final thoughts and notes on the Ocho's performance, so you can expect a long-term review in the near future.

In the meantime, tell us what you make of Cannondale's single-sided, single-crown suspension fork... Is it too different for you, or do you care what it looks like so long as the performance is there?

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