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.
1. Looks
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.
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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.
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Winner: 2021 Topstone Carbon Lefty 1
3. Versatility
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.
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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.
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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...
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Winner: 2021 Topstone Carbon Lefty 1
6. Bottom bracket shell
I’m not going to get into the relative merits or otherwise of press fit bottom brackets here, but both the Slate and Topstone use Cannondale’s BB30a, the update to the original BB30 standard. (For what it's worth, I’ve had zero issues on the Slate, despite using and abusing it for the best part of four years in all weathers).
Instead, I’m going to talk about how they look and how the shell integrates into the frame.
The Topstone does the latter very well. The carbon is shaped and smoothed to avoid any dirt getting trapped in nooks, and the stays smoothly integrate to create generous space for big tyres.
The flattening seat tube and boxy down tube all flow into the BB shell very organically – this thing has been styled and smoothed to the nth degree.
As for the Slate... well it’s, errr, generously sized, and has some rather large, but very even fish scale welds that join the oversized down tube and boxy chainstays to the ovalised and flattened seat tube.
The chainstay yoke creates a shelf behind the seat tube, with the front mech cable piercing through its centre, and this makes for quite the mud trap in my experience.
It’s all nicely old-school in its execution, but in aesthetic terms alone it’s outgunned by the Topstone.
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Winner: 2021 Topstone Carbon Lefty 1
7. Drivetrain
The Slate came along when gravel gearing was in its infancy; SRAM had 1x but Shimano hadn’t even thought of GRX yet.
So the Slate Ultegra effectively has road gearing, and high-performance road gearing at that with a 52/36t chainset and an 11-28t cassette out back. That’s why this bike is such a demon on the road – it’s got the gearing for it.
To be fair, it’s been pretty decent off-road too, but when things get steep or technical the Slate is clearly going to struggle with its lowest 36/28 gear. I have ended up bike-hiking the Slate on occasion, and it’s something I’ve been meaning to address pretty much since I’ve had the bike.
However, my Slate does sport Ultegra, so has proved to be reliably robust, and I’ve always liked Cannondale’s Spidering-equipped chainset.
The Topstone, of course, is bang up-to-date in terms of gearing (it’s a 2021 model and we’re only in May).
The flagship bike’s drivetrain combines Force AXS shifters, from SRAM’s road group, with the gravel-specific Force carbon chainset and its single 40t chainring.
Out back there’s an Eagle X0 AXS derailleur matched to the machining marvel that is SRAM’s Eagle 10-50t 12-speed cassette. That gives a bottom gear of 40/50, low enough to climb a wall.
This mullet drivetrain (short at the front, long at the back) is where the gravel cutting-edge is right now and, as this is a gravel bike shootout, the Topstone proves its worth again.
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Winner: 2021 Topstone Carbon Lefty 1
8. Components
The battle is a little off-kilter here because my Slate wasn’t the range-topping bike (it sat second in line), so it’s not a like-for-like comparison. However, in the spirit of this Top Trumps-style Battle of the Bikes, it’s worth taking a closer look at both specs.
The Slate Ultegra was priced at £2,799 – no doubt that’s pretty expensive in relative terms for an aluminium-framed bike. The fork was the big expense at around £1,500 alone – the new Lefty will be $1,500 as an aftermarket upgrade when available.
My Slate came with mechanical Shimano Ultegra but with Cannondale’s own Si chainset and the cool-looking eight-arm Spiderring. Now I’ve had it a few years I’ve also made a number of changes to the spec.
I upgraded the tyres almost immediately (£84 a pair) and switched out the fairly basic alloy back wheel for a carbon unit (£400).
I also changed the saddle to a Fizik Aliante VSX (£99.99) and put on a super-flared Ritchey Venture Max WCS bar (£88) because the original was a standard alloy Cannondale C2 bar with no concession for gravel.
Finally, I added a HideMyBell Garmin mount – I think gravel bikes should have a bell to warn other trail and track users.
Again, I'm not comparing apples with apples here, but, with upgrades included, you could say my Slate would be around £3,500 as seen.
The new Lefty 1 I’ve got here is the flagship Topstone, with a collection of top-grade parts, but it will set you back £6,600. The spec list includes SRAM’s AXS Eagle and Force drivetrain components, carbon Hollowgram wheels and premium WTB tyres.
The drivetrain is wireless, as I’ve already mentioned, and offers gravel-friendly gearing, while the Hollowgram wheels are in line with modern trends at 23mm internally, with a claimed weight of less than 1,400g.
The tyres are well thought out with a WTB Byway out back matched to a grippier WTB Venture up front. The saddle is Fabric’s classic Scoop with fancy titanium rails.
The cockpit is the SAVE carbon/alloy bar and stem found on the top-spec, five-star SuperSix EVO race bike we reviewed recently, with the two-piece aero design that looks integrated but still offers adjustability.
On paper there’s nothing I’d look to change or upgrade, it looks the business and exactly what you want from a bike that costs £6,500. An easy win… if you’ve got deep enough pockets.
If the veteran Slate does take your fancy, there are bargains out there if you’re prepared to look around. Providing you’re also prepared to live with a few of its quirks, there’s still a huge amount of fun to be had.
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Winner: 2021 Topstone Carbon Lefty 1
9. Weight
Bike weight always needs a little context but everything here has been weighed on my scales.
The new Topstone Carbon Lefty 1 in its out-of-the-box specification weighs in at 10kg on the nose for a large (58cm) frame. In riding trim, which means a pair of steel bottle cages and a set of Shimano XT mountain bike pedals, that nudges up to 10.7kg.
Meanwhile, the Slate surprised the scales by coming in at 10.6kg in a size XL (a 58cm equivalent), with a set of Ritchey WCS Trail pedals, two plastic cages and a HideMyBell mount.
The Slate takes the win by 100g – or about the weight of six chocolate chip cookies or four AA batteries...
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Winner: 2016 Cannondale Slate Ultegra
The winner… 6-3 to the 2021 Topstone Carbon Lefty
Cannondale’s new Topstone Carbon Lefty beats out the veteran Slate in a fairly comprehensive 6-3 victory.
This, of course, isn’t a comprehensive test – and is subjective on my part – but I’m looking forward to seeing how the two bikes compare out on the road/trails.
I’ve been a big fan of the non-Lefty Topstone Carbon since it arrived last year and, in launching this latest version, Cannondale looks to have a boundary-stretching gravel bike to replace the Slate.
Full specs and weights
Cannondale Slate Ultegra (with upgrades)
- Weight: 10.6kg (XL frame, including pedals and cages)
- Frame: Smartform 6069 Alloy
- Fork: Carbon Lefty Oliver with 30mm travel, 45mm offset
- Gears: Shimano Ultegra (52/36t, 11-28t)
- Chainset: Cannondale Si chainset with 52/36 Spidering
- Wheels: Slate 650b disc, with Lefty front hub, rear 650b Roval CLX
- Brakes: Shimano BR-RS805 hydraulic disc
- Tyres: Specialized Sawtooth 2Bliss 42mm tyres
- Seatpost: Cannondale C2 seatpost
- Handlebar: Ritchey VentureMax WCS bar
- Stem: Cannondale C1 stem
- Pedals: Ritchey WCS Trail pedals
- Saddle: Fizik Aliante VSX saddle
- Extras: HideMyBell Garmin mount, two RaceOne plastic bottle cages
Cannondale Topstone Lefty 1
- Weight: 10.7kg (L, including pedals and cages)
- Frame: Ballistec Carbon frame, Kingpin suspension
- Fork: Lefty Oliver Carbon, 30mm travel, 55mm offset
- Gears: SRAM Force shifters, Eagle X0 AXS rear derailleur, Eagle 10-50t cassette
- Chainset: SRAM Force AXS, dub spindle, 40t
- Wheels: Cannondale Hollowgram 23 Carbon
- Brakes: SRAM Force hydraulic disc
- Tyres: WTB Venture (front), WTB Byway (rear)
- Seatpost: Hollowgram SAVE carbon
- Handlebar: Hollowgram SAVE carbon system bar
- Stem: Hollowgram SAVE stem
- Pedals: Shimano XT
- Saddle: Fabric Scoop Shallow Race Ti
- Extras: Hollowgram out-front mount, two Elite steel bottle cages
