Six years on from the launch of the radical Slate gravel, Cannondale has added a suspension fork to its latest gravel bike to create the Topstone Carbon Lefty.
With 30mm of bounce front and back thanks to the Kingpin soft-tail and new Lefty Oliver fork, the Topstone Carbon Lefty is a full-suspension gravel bike likely to divide opinion as much as the original Slate.
The Slate was introduced for 2016 and, while the bike is no more, it’s a machine that deserves high praise, bringing suspension to a gravel bike at a time when gravel bikes were just a seed in the minds of the bike industry. It was a bike before its time.
After reviewing the original Slate I took it on as a long-term test bike and, when time was up on that, I knew it was a bike I had to own, so it has stayed in my (admittedly overstocked) personal bike collection. Is N+11 a thing?
Following on from my Giant TCR Battle of the Bikes, I fancied pitting the new full-suspension Topstone Carbon Lefty bike against a bike that was, in its day, arguably even more more radical than the 2021 machine. Before we get started, you can read all about the new Topstone Carbon Lefty here.
When the original Topstone Carbon launched last year I mooted here, and to anyone who would listen at Cannondale, that this bike should get a Lefty, just like the Slate, to make it truly unique (nobody else had a full production, full-suspension gravel bike on the market at the time).
Since then, of course, the coronavirus pandemic has taken hold. We’ve paused our testing programme for the time being, so that means a proper head-to-head test isn’t on the cards – but it has given me the chance to paw over every last detail of the new Cannondale Topstone Carbon Lefty and compare it directly with my venerable Slate.
This is my own comparison based on my time owning the Slate, and the Topstone Carbon Lefty 1 as it appears out of the box. It’s based purely on my own opinion, so whether you agree or disagree, let me know what you think in the comments.
The look of any bike is so subjective. When the Slate launched in 2016 it divided opinion; some loved its rugged aluminium frame and that oh-so-imposing twin-crowned Lefty fork, while others thought it looked like a 650b hardtail mountain bike wearing a drop bar disguise.
I was firmly in the former camp and still think this bike looks killer today. The understated battleship grey paint with that massively manipulated aluminium tubing, with the massive head tube and fork, make it stand out.
The Topstone’s carbon frame, on the other hand, is much more subtle. The rear suspension may be new but it’s nearly hidden and the Lefty fork is less imposing with its single-crown design, based on the Ocho mountain bike fork.
The details, along with the gorgeous metallic paint and subtle Cannondale graphics make the Topstone Lefty look like a bike that was built by serious engineers, with serious industrial designers, and serious graphic design considerations for an air of total professionalism.
The Slate, on the other hand, looks like a bunch of folk at Cannondale put something together that they just fancied riding… but I still love it.
Winner: 2016 Cannondale Slate (we all love an underdog)
2. Frame details
The Slate showcases everything good about Cannondale’s manipulation of aluminium. Look at the way in which those seat and chainstays are flattened and broadened to add comfort.
The Smartform frame (it’s not given any CAAD nomenclature) mixes traditional manipulation, hydroforming, burly welds and oversizing to create a purposeful and tough-looking machine.
The Topstone and Slate both have internally-routed cables, though the Lefty 1 here only has the hydraulic hoses for the brakes because it comes with SRAM’s wireless AXS components.
The Topstone’s tube shapes are superbly realised and details such as the size-specific seat tube diameter for tuning comfort and stiffness are also impressive.
The rear dropout is a Speed Release thru-axle with a fast, double-line thread as opposed to the standard 142 x 12mm thru-axle found on the Slate. So wheel removal should be quicker and the axle remains in the hub rather than needing to be removed and placed on filthy ground.
We’ll come on to weight later, but Cannondale claimed the aluminium Slate frame weighed 1,250g, while the carbon Topstone is much lighter at a claimed 1,100g.
Winner: 2021 Topstone Carbon Lefty 1
The Slate has mounts on the stays, like the Topstone, to fit a ‘guard/fender (with a removable seatstay bridge), and the Lefty fork has a few options for fenders, all in mountain bike dimensions, but with only two bottle mounts.
The Slate lacks mounts for true bikepacker appeal and it’s got the hugely oversized head tube that denotes the last gen Lefty design, meaning you are pretty much stuck with the stem it comes with.
On the other hand, the Topstone gets a removable mudguard/fender bridge like the Slate, but also has additional mounting options on the down tube bottle bosses, and on the top tube for a bento box.
As for wheels and tyres, the Slate is designed as a 650b bike. Yep, you ‘could’ go 700c if you had a wheelset built, but the slender back-end would limit tyre width to road-sized tyres. Official tyre clearance (which we’ll come on to) was 42mm with 650b wheels.
Originally, the Slate came with fat slicks, but I found them really fragile so settled on mildly-treaded Specialized Sawtooth tyres, to give it a bit of all-road versatility.
The Topstone Lefty comes with 650b wheels and a set of 45mm tyres (the regular, non-Lefty Topstone gets 700 x 37mm rolling stock out of the box), with a maximum stated clearance of 47mm. With 700c wheels you can go up to 45mm.
The geometry of the Topstone is based around the Synapse endurance bike, whereas the Slate is a little more aggressive.
The non-Lefty Topstone has all the makings of a one-bike-for-all machine, with good on road manners, whereas this new bike has much more of a dirt focus.
That said, the geo numbers remain the same as the regular Topstone and the fork has a lock-out, so it should in theory ride as well as its two-legged sibling on the road and way beyond off. So the Topstone has the edge again.
Winner: 2021 Topstone Carbon Lefty 1
4. That fork!
The original Lefty Oliver Carbon on the Slate is, in my opinion at least, a great-looking thing. The length, diameter, fittings and fixings all make it stand out as something different and very special.
The anodised parts and woven carbon checkerboard finish on the legs also help. I love the look of the lock-out, with its contrasting, dual-ring anodised pieces and etched ‘lock to climb’ markings. The outer ring also offers a bit of on-the-fly rebound adjustment and, because it’s at the top of the long fork leg, it’s easy to reach as you ride.
As for weight, the Slate’s original Lefty Oliver comes in at a claimed 1,170g, which is impressive when you consider the sheer size of it!
The new Lefty Oliver is based on Cannondale’s Ocho mountain bike fork and is apparently stiffer, with faster bump reaction performance and better steering precision.
The whole brake assembly can now be quick-released to make wheel removal simple – on the old Oliver you had to undo the brake’s hex bolt mounts manually. The lock-out also includes a clever blow-off function should you hit something, which is handy because the lever is down on the lower crown so a bit harder to reach when riding.
The rebound is now isolated from compression and Cannondale claims it offers a 60 per cent improvement in rebound range over the 2016 bike.
Surprisingly, however, the new Oliver weighs more than the original at 1,340g, but that’s significantly less than the mountain bike Ocho fork in its lightest guise.
The new fork looks smaller overall (though the crown is broader, as is the tyre clearance) and Cannondale of course claims the revamped design outshines the original both on paper and in terms of performance. It’s also available in an alloy version, as well as carbon, to reduce the cost.
But I still have a soft spot for the mad looks of the original, even if it means you have to have a specific frame design and a specific stem. I love that the old Lefty has a bit more anodised bling and it shows off its carbon design, whereas the new Lefty is all painted black.
Controversial, maybe, but until I’ve ridden the new Lefty Oliver fork I’m going with my heart and sticking with the Slate.
Winner: 2016 Cannondale Slate Ultegra
5. Tyre clearance
In hindsight, Cannondale must have been kicking itself over the Slate’s relative paucity in tyre clearance.
In 2016, 42mm with 650b wheels was generous but not exceptional, and not in the same league as the likes of Open’s UP, which could run 2in tyres. I’ve squeezed slightly broader 45mm tyres into my Slate, but that leaves almost no clearance, so I wouldn’t recommend it.
It’s the one bugbear I have with the Slate, especially because gravel wheels are getting broader and tyre options are expanding at the same time. So, it is now, without doubt, quite limited.
The Topstone, on the other hand, has space for 45mm with 700c wheels and 47mm in 650b. That’s not as wide as the likes of the new Specialized Diverge (47mm for 700c, 2.1in for 650b), but if you do need to go bigger there’s always a mountain bike…
Winner: 2021 Topstone Carbon Lefty 1