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Cannondale’s path in gravel started with the aluminium Slate, a ground-breaking bike that featured a take on its lefty suspension fork – the single-legged design that’s been a staple of Cannondale’s off-road offerings for more than a decade.
The carbon lefty fork (called the ‘Oliver’) is an impressive bit of tech and works superbly, but its prohibitive cost (in excess of £1,000) meant the Slate came up as a pretty expensive gravel option, especially one that ‘only’ had an alloy frame.
Later, the original value-packed Topstone alloy arrived, and now we have the all-new carbon Topstone (which bears no resemblance to its alloy namesake) bringing back the innovation that sets Cannondale apart.
The Topstone Carbon Ultegra RX has a suspended rear-end that cleverly forgoes a shock unit to keep weight (and costs) down. Yet, with the pivoted rear end and flexibility in the stays, it gives up to an impressive 30mm of suspension travel at the saddle.
Bike of the Year 2020
The Cannondale Topstone Carbon Ultegra RX is part of our annual Bike of the Year test.
Cannondale’s leaf-spring design is proportional to the size of the bike.David Caudery / Immediate Media
The absolute key feature of the Topstone is its back-end, using what Cannondale is calling its ‘Kingpin’ suspension system.
The design maximises compliance in the seat tube with the pivot design and, of that 30mm suspension total, only 25 per cent (7.5mm) is at the rear axle.
That means the seat tube effectively acts as a leaf spring combining with flex zones in the seat and chainstays and that maintenance-free pivot point holds everything together.
Cannondale claims a frame weight of around 1,100g – pretty impressive stuff for a bike with 30mm of travel at the rear.
Pivot-less rear suspension isn’t a new thing for Cannondale, its 2017 Scalpel mountain bike features a back-end with no linkage at the rear axle, instead relying on SAVE carbon to activate the shock. And it’s clever carbon innovations such as this that have allowed for a design like the Topstone.
The clever thing with the leaf-spring design is that it’s proportional to the size of the bike, and, when you compare the width of the thinnest section of the seat tube on the small with that of the extra-large, the difference is marked – 16mm on the small and 28mm on the XL.
The frame offers dual wheel size compatibility with tyre clearance of 40c in 700c and 48c in 650b.David Caudery / Immediate Media
The tube cross-sections change according to size, and the laminate design also changes by size, meaning stiffness is scaled to deliver a consistent experience whatever size the rider.
The frame also offers dual wheel size compatibility with tyre clearance of 40c in 700c and a large 48c in 650b, so whatever terrain you’re looking to ride, getting the right tyre option shouldn’t be a problem.
Cannondale Topstone Carbon Ultegra RX kit
The ‘adventure’ 2x gearing with a smaller 46/30 chainring pairing and 11-34 cassettes, could give the impression of being a bit too ‘spinny’ on the road and even under-geared. Yes, to a certain extent it does require a higher cadence if you’re riding on the road with others on road-specific bikes, so you end up with a more ‘aerobic’ ride experience than relying on sheer power.
Off road, the gearing is a must to keep you riding when the surface deteriorates or the gradient steepens.
Cannondale uses mechanical Ultegra with the RX clutch mech at the rear to control chain bounce – a necessary upgrade for riding in the rough. And its uses its own Hollowgram chainset with the one-piece machined Spider-ring in tow, a good-looking (and lighter) alternative to Ultegra.
Fabric Scoop saddle on a Save carbon post.David Caudery / Immediate Media
It also supplies its own wheels in the form of lightweight Hollowgram 22 carbon units. These shallow (22mm deep) hoops have a very broad 25mm internal diameter, are tubeless-ready and tip the scales at around a kilo and a half – helping keep the Topstone down to a scant 9kg in a size large with big 37c off-road tyres fitted.
The Topstone does, however, need to be run tubeless (it came set up with tubes) because, like the GT Grade with the same Riddler tyres, it proved prone to punctures – after converting the bike to tubeless the problem was solved (and a little weight saved).
Shimano Ultegra hydro disc brakes with 160mm rotor.Russell Burton
If you’re venturing onto gravel, then venture to tubeless at the same time – you won’t regret it.
On longer rides, the Topstone showed its mettle on the tarmac, it’s a bike that feels fast, powerful and superbly composed, stable even.
The Topstone performs well on and off road.Russell Burton
When you head off-road it’s a similar feeling – the Topstone on straight gravel roads is blisteringly quick, the rear-end’s compliance is subtle and superb, and it never gave the suggestion of ‘bobbing’, even when powering along seated or in the drops giving it the full beans.
The back-end’s smoothness is a good match for the Topstone’s front end too – firm, but never harsh. It only adds to the overall impression the Topstone gives.
If you’re looking to compete in a gravel race, the Topstone is worth considering.Russell Burton
It’s a bike built to go fast, so if your idea of a gravel day out is a competitive event, then the Topstone is worthy of some serious consideration.
If you venture further off-road it’s not quite the match for the playful GT when it comes to tight technical stuff – it has more in common with Cervélo’s Aspero in that respect – though it does come with an added layer of compliance from the oh-so-clever back-end.
Cannondale Topstone Carbon Ultegra RX bottom line
A gravel bike that can cut it on the road with the best.Russell Burton
As good as the Topstone is off-road, it’s on the road where it really shined. The geometry on my size large test bike of 610mm stack and 394mm reach is pretty much the same as a Synapse (bar a millimetre in reach), so it feels every inch the rapid endurance bike.
With a set of road tyres it’s a wonderful weapon against the UK’s poor winter roads, the back-end providing incredible compliance yet feeling fast and surefooted with it.
The Topstone – like the Cervélo Aspero and GT Grade – offers compelling reasons for the ‘one bike for all’ argument. If you’re looking to declutter your bike stable then the Topstone could be what you are looking for.
Approaching two decades of testing bikes, Warren can be found on a daily basis riding and exploring the road and off roads of Wiltshire’s Salisbury Plain in the UK. That’s when he’s not travelling the world to test the latest kit, components and bikes.