Cannondale Topstone Carbon Lefty review: Suspension makes it better

The new Cannondale Topstone Carbon Lefty is basically the same as the standard Topstone Carbon, but now with a suspension fork and a switch to 650b wheels and tires. The changes sound modest on paper but the difference you feel in the saddle is far greater than you might expect, and while that Lefty Oliver fork adds a fair bit of weight, it more than makes up for it in terms of capability and sheer fun. More importantly, it arguably makes for a more balanced and cohesive machine than the standard version.

If mixed terrain is more your style, the standard Topstone is still the better choice. But if your idea of gravel riding leans more toward the off-road end of the spectrum, this is the Topstone to get.

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It’s all about the fork

The Topstone Carbon Lefty’s defining feature is that ultra-distinctive Lefty Oliver fork. On the surface, it’s just a cut-down version of the Lefty Ocho that Cannondale uses on its F-Si range of 29er cross-country hardtails, and has just 30 mm of travel instead of 100 mm. However, according to Cannondale, the air spring and damper tuning are very different, and it’s that tuning that makes the Lefty Oliver what it is.

Mountain bike suspension forks are invariably designed to run with something called sag — basically, rider weight alone is supposed to compress the fork a little so that it can better track the terrain. Almost without fail, this is accomplished using a combination of positive springs (which work to extend the fork) and negative ones (which work to compress the fork). The Lefty Oliver uses only a positive spring, however, and doesn’t sag at all under normal riding conditions.

Moreover, the hydraulic damper that keeps all of this motion under control is built with a firmer compression and rebound tune than normal. In other words, it’s not as bouncy-feeling as a mountain bike fork with more travel, which seems appropriate here given the application. There’s also a manual lockout lever atop the single-sided crown if you really don’t want the thing to move at all (if you’re on an extended section of tarmac, say).

On paper, then, long-time mountain bike tech nerds might immediately recognize all of this as the typical hallmarks of a crummy suspension fork. But yet Cannondale obviously claims otherwise, saying the breakaway threshold for when the fork is designed to start moving is carefully engineered so that it’s still active when you actually want it to be, but without the excess movement that riders in this category would invariably dislike.

Despite the lack of sag, Cannondale says the Lefty Oliver is very sensitive on smaller bumps, too — or, at least, as sensitive as it needs to be. Helping matters along in that area (along with that careful damping and spring tuning) are three rows of needle bearings that separate the inner and outer legs of the fork, instead of the solid bushings used in every other brand of telescoping fork on the market that are more apt to bind up when encountering a bump in the (off-)road.

Suspension benefits aside, all of this hardware adds up to a lot of weight relative to the rigid carbon fork of the standard Topstone Carbon.

Cannondale makes the Lefty Oliver in two different versions: one with a forged aluminum crown and upper section (such as what’s included stock on the Topstone Carbon Lefty 3 model that I’m reviewing here), and another with a carbon fiber assembly. In either case, the lower half of the fork is made of forged aluminum, including the tapered stub-axle onto which the proprietary front hub attaches.

Claimed weight for the alloy Lefty Oliver is 1,610 grams, while the carbon one is substantially lighter at 1,340 g. In comparison, the regular Topstone Carbon fork is less than 500 g, so you’re looking at a penalty of more than 800 g, at minimum.

There are a few other neat details on the Lefty Oliver, too.

For one, the Lefty Oliver fits in the exact same tapered head tube as the standard Topstone Carbon fork, and the axle-to-crown length and rake are identical as well. As a result, there’s not only no real change in steering geometry, but current Topstone owners can also add the Lefty Oliver to their existing bikes. Clearly, some longer-term foresight was in play here.

Cannondale is only offering the Lefty Oliver in aftermarket form in the carbon version, though, so those current Topstone owners will have to feel pretty flush with discretionary income. Retail price is US$1,500, and that doesn’t include the proprietary wheel that goes with it.

Also, since Lefty front wheels slide axially off of the stub axle during removal, the disc brake caliper has to be removed as well. In the past, this was a cumbersome process that required loosening the caliper mounting bolts, but the Lefty Oliver has a nifty quick-release bracket that turns it into a rather painless operation — and since it’s self-locating, you don’t need to readjust the caliper after you put everything back together.

Smaller wheels for bigger fun

Cannondale has always touted the Topstone Carbon’s ability to run either 700c or 650b gravel wheel-and-tire setups. However, standard Topstones have all been supplied stock with 700c configurations in the interest of lower weight and faster rolling.

However, Cannondale is assuming (probably rightfully so) that riders who choose the Lefty-equipped version are not only more likely to ride on unpaved surfaces, but on tougher gravel, dirt, and trails in general. As such, all Topstone Carbon Lefty models get smaller-diameter 650b wheels wrapped in wider and more aggressively treaded tires.

In addition to providing more grip and air volume than the 700×37 mm tires that standard Topstones get, the slightly smaller overall diameter of the 650b setup also lowers the ride height for a tad more stability on rough terrain.

All in all, it’s probably a smart move.

It’s still a Topstone Carbon

Aside from the fork and wheels, the rest of the bike is wholly unchanged from the standard Topstone Carbon, with the key feature still being the Kingpin pseudo-suspension rear end.

You can read about the system in more detail in my original feature from the Topstone Carbon’s launch. But in summary, the whole setup is designed to provide up to 30 mm of claimed travel at the saddle when hitting a bump, through a clever system of flattened carbon frame sections, a single mechanical pivot at the seat tube, and a flexy 27.2 mm-diameter carbon fiber seatpost.

And while you may be skeptical (I certainly was before I rode it), it actually works.

Also carrying over is the sporty-feeling frame geometry and a panoply of controversial Cannondale-specific features required to make it that way, such as the Ai asymmetrical rear end and extra-wide BB30a press-fit bottom bracket. Cannondale says that both of those are essential to the Topstone Carbon being what it is, but they’re also more than a little controversial given their proprietary nature.

Take it or leave it.

Models and availability — and yes, there are e-versions, too

Cannondale is offering the new Topstone Carbon Lefty in just two versions, at least for now. There’s the mid-range Topstone Carbon Lefty 3 that I’m reviewing in detail here, equipped with the aluminum Lefty Oliver fork, a 1×11 Shimano GRX 800 mechanical groupset, Cannondale One crankset, and WTB aluminum rims and 47 mm-wide tires laced to generic aluminum hubs.

Retail price is US$3,750 / AU$5,500 / £3,400 / €3,800, and actual weight for my small-sized sample is 10.41 kg (22.95 lb), without pedals or accessories — hardly light, but still nearly a kilogram lighter than the Niner MCR 9 RDO we recently reviewed at our Gravel Bike Field Test.

At the upper end is the Topstone Carbon Lefty 1, fitted with the lighter-weight Lefty Oliver Carbon fork, a SRAM Force 1 AXS “mullet” drivetrain with a SRAM Eagle 10-50T 12-speed rear cassette, Cannondale Hollowgram 650b carbon wheels, a cushier-riding one-piece Cannondale SAVE carbon fiber seatpost, and a semi-integrated Cannondale SAVE SystemBar integrated bar and stem. Retail price is US$7,500 / AU$TBC / £6,500 / €7,500.

There are also several Topstone Neo Carbon Lefty models on tap, with Bosch mid-drive e-assist motors and integrated batteries. We’ll cover those in more detail in the near future.

A transformative ride

Casting aside for a moment the arguments about all of the dedicated equipment on the Topstone Carbon Lefty, the simple fact of the matter is that this bike is an outrageous amount of fun to ride. As in, so much fun that I legitimately don’t want to give it back. So much fun that I almost don’t care how much it weighs (more on that in a bit). So much fun that I think I could even live with all of that proprietary stuff if it means you get a gravel bike that is this entertaining to ride.

I’ll elaborate.

I wrote at length in my review of the standard Topstone Carbon about how well the back end works. It’s surprisingly smooth and very comfortable, but also improves performance since it allows you to stay seated and on the gas more over rough terrain, while also providing a subtle boost in drive and cornering traction. However, as is often the case with bikes that have notably cushy rear ends (the Trek Checkpoint SL is another one that immediately comes to mind), the Topstone Carbon also feels a bit unbalanced in the sense that the front end is comparatively much firmer-riding, almost to the point of being disruptive when things get bumpy.

That all changes with the addition of the Lefty Oliver fork.

Gravel front suspension features have invariably felt a little half-hearted to me. The Specialized Future Shock (even the new 2.0 version on the latest Diverge) seems a little too rudimentary and uncontrolled in my opinion, the Lauf Grit leaf-spring carbon fiber fork feels bouncier and doesn’t steer as well, the Redshift ShockStop stem changes the handlebar angle as it moves, and the Fox AX fork always feels like the repurposed obsolete mountain bike fork that it is.

Just like I found with the Kingpin rear end on the standard Topstone Carbon, though, I’ll be damned if the fork doesn’t work just as Cannondale claims it does. Simply put, this is the best gravel-centric front suspension I’ve used to date.

As promised, it hardly moves at all when you’re motoring along on smooth ground, and unless I expected to be climbing a lot out of the saddle on paved roads, I almost never bothered to engage the manual lockout. But on dirt and gravel, it doesn’t take much of an impact at all for the fork to wake up and get to work, swallowing up all sorts of impacts that you can see, but barely feel. The fork even works much better than I expected on washboard, perhaps due to the silky-smooth movement of those three rows of needle bearings.

Cannondale’s engineers easily could have just tossed their hands in the air and not bothered to spend much time on the air spring and damper tuning since there’s so little travel on hand. However, I’ve always adhered to the philosophy that the quality of your suspension is more important than the quantity, and that approach definitely applies here.

I found that the fork does have a very narrow window of air pressure where it all feels just right, but it’s worth spending the time to experiment. The air spring is suitably progressive so that bigger impacts are handled with far more composure than you’d expect given the modest amount of travel, and the damping seems perfectly tuned such that rocks and roots are essentially leveled.

Throughout it all, the front end doesn’t seem overly isolating and numb, and the steering precision is just as good as with a rigid carbon fork with the same flickable and playful nature that I so enjoyed on the standard Topstone Carbon.

Especially when combined with the bigger footprint of the 650b tires, what you get as a result is a gravel bike that’s arguably faster overall than the lighter unsuspended version on which it’s based, and a strong argument for the merits of suspension in gravel in general — at least when it’s done this well.

As good as it is, though, you can’t completely ignore that additional mass, especially on the alloy version, which adds more than a full kilogram right up front. It feels fine on flatter or rolling terrain, but it’s more cumbersome on longer climbs or steeper pitches when you’re really trying to make a big acceleration. If the idea of quality gravel bike front suspension speaks to you, my advice would be to pony up for the nicer carbon version (assuming you can afford it).

There are also the same annoyances present and accounted for here as on the regular Topstone.

While I can appreciate the packaging benefits the asymmetrical rear end affords — that 415 mm-long rear end really is pretty fantastic — the resultant compatibility issues will be a dealbreaker for many potential buyers.

Although many standard rear wheels can be adapted to fit, that won’t be the case for all of them, and it’ll be a hassle nonetheless. And although I didn’t experience any creaking from the BB30a press-fit bottom bracket on my test bike, Cannondale doesn’t exactly have the best track record here. And yes, the hidden wedge-type seatpost binder still looks very neat and clean. But yes, it’s also prone to slipping without generous applications of friction paste, and is just generally kind of a pain.

Spec notes

In terms of the build, this Topstone Carbon Lefty 3 is mostly pretty unremarkable.

We’ve written at length about the merits of Shimano’s GRX mechanical groupset, and nothing has changed since. It’s basically the gravel equivalent of Ultegra, which is to say that it’s brilliant stuff. Shifts are impeccably smooth, the hydraulic disc brakes are strong and highly controllable (albeit also prone to howling when wet), and the lever ergonomics are spot-on.

That said, this 1x variant has a curious quirk in that the left-hand shift lever is locked out, but still moves a little. It’s not an issue functionally, but it still feels a little wonky.

Cannondale also substitutes in its solid-forged One aluminum crankset in lieu of the standard GRX unit. It works fine — there’s not much to a 1x crankset, after all — but some might be bothered by the slightly wider Q-factor. YMMV.

The tire selection is brilliant. WTB offers a remarkably broad range of gravel tires, and the 47 mm-wide Venture used here is very well suited for the task. It’s a bit slower-rolling than the 700×37 mm WTB Riddlers that come on the standard Topstone Carbon, but the fine paddle-like center tread offers more reliable grip on loose-over-hardpack surfaces, while the more aggressive shoulder blocks provide more free reign for recklessly throwing yourself into corners.

My particular test bike came with those Ventures front and rear, but production bikes are supposedly equipped with a faster-rolling WTB Byway out back. Personally, I think the Ventures make more sense.

Those tires are mounted to 23 mm-wide WTB i23 aluminum rims, which set up tubeless and have generally held up alright based on previous experience. The rear hub is woefully generic, though, and doesn’t even bear Cannondale’s own logo. Engagement speed is slow, and long-term durability for that part will be anyone’s guess.

Finally, the flared aluminum bar and forged aluminum stem get the job done just fine. Likewise, the stock Fabric Scoop saddle is one that’s quite popular and generally well-liked. However, the midsection is quite narrow and the nose rather long, so most riders will find themselves most comfortable perched more toward the rear end. That’s not a problem in and of itself, but Cannondale has mounted that saddle atop a setback seatpost, and the combination feels further rearward than you might expect.

The seatpost itself is also a massive pain to adjust since the Allen head fitting on the forward bolt isn’t accessible without a cutout in the saddle, and there’s so much Loctite on the threads that the knob that’s supposed to allow for tool-free spinning is worthless, too.

A riotously good time

If you’ve gotten the impression that I really like this thing, then the message has come across as intended. This bike is not only exceptionally entertaining, but a strong testament to the benefits of suspension for gravel riding when it’s done well.

Would I like it to be lighter? Sure. Is it weird to look at? Definitely. And would I be happier without all the proprietary Cannondale goofiness? Absolutely.

But holy crap, do I have a big, silly grin on my face every time I ride this thing.

www.cannondale.com