Cannondale’s Topstone gravel bike gets shockless leaf-sprung rear suspension

The new carbon Cannondale Topstone features an all-new, ultra-light Kingpin suspension system

Cannondale has today launched the Topstone, a radical carbon do-it-all gravel bike with a unique shockless leaf sprung rear suspension system that relies on the flex of the rear end to provide damping in rough terrain.

Cannondale got into the gravel-market pretty early on with the radical Slate, and while the Slate has certainly earned a lot of fans (including me, I own one), it was a little limited on tyre and wheel size (650b only), not to mention expensive for an aluminium bike — that full-carbon Lefty suspension fork doesn’t come cheap.

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The Slate was followed by last year’s Topstone aluminium range, which has proved a big success at the more affordable end of the gravel bike market, and it’s now completed by the premium Topstone carbon with prices ranging from £2,099.99 / $2,700 up to £4,799.99 / $6,500.

Product director, David Devine, gave us the background on the Topstone’s development: “We aimed to make the most comfortable, capable gravel bike available. To that effect, the fit is more endurance biased, like the Synapse. It has our highest stack progression (taller and shorter) and it shares the position with the Synapse.

“At the other end of the spectrum you have the SystemSix, our lowest and longest bike, and the Evo sits in the middle. The goal [with the Topstone] is to be upright enough for comfort and confident off-road riding yet still low enough to make for a fast road bike.”

Simply sprung

Red black road bike
We’ve been out testing the Topstone Force AXS
Warren Rossiter/Immediate media

The key feature of the Topstone’s frame design is the back-end, using what Cannondale is calling its ‘Kingpin’ suspension system.

The man behind the design is Darius Shekari, Cannondale’s lead engineer for suspension. He tells us that “the new Kingpin suspension offers 30mm of travel at the saddle, with around 25 percent of that (7.5mm) at the rear axle. We’ve engineered the seat tube to work as a leaf-spring, with flex zones in the chainstays and top tube.

“The pivot at the top of the seatstays runs on a maintenance-free bearing allowing this level of movement without the complexity or additional weight of a shock unit and linkages.”

To this end, the frame weight is claimed to be around 1,100g, which is pretty impressive stuff for a bike with 30mm of travel at the rear.

Seatstay on red black road bike
The Kingpin rear-end pivots around this seatstay mounted bearing
Warren Rossiter/Immediate media

Now, pivotless rear suspension isn’t a new thing for Cannondale. Its 2017 Scalpel XC bike featured a back-end with no linkage at the rear axle, again relying on the flex of the carbon rear end.

I asked Devine and Shekari if the jump-off point for the Topstone’s back-end was the Scalpel, and Devine says that they “tried pretty much every configuration we could think of, but one of the key elements had to be that the Topstone wasn’t compromised weight-wise by the design.

“So the many, many months of investigation, experimentation and testing all came to the combination of developments on our SAVE carbon technology and the back-end configuration.”

The leaf spring design is proportional to the size of the bike, and when you compare the width of the thinnest-section of the seat tube on the small to the extra-large, the difference is marked: 16mm on the small and 28mm on the extra-large.

The tube cross-sections change according to size and the laminate design also changes by size, which means stiffness is scaled to deliver a consistent experience whatever size the rider.

The front of the bike uses a new out-front geometry design where the dedicated carbon fork is running a 55mm offset. For comparison, the Synapse uses a 45mm offset.

Cannondale claims this keeps the steering feel light and agile, even with big volume tyres, while adding stability in the rough with the added benefit of reducing the chances of toe-overlap, which is where the rear of the tyre hits your foot when turning tightly.

Seatstay wheel clearance
Tyre clearance at the rear is generous in both 700 and 650b wheel sizes
Warren Rossiter/Immediate media

The bike is compatible with both 700c and 650b wheels with a generous tyre allowance, and Cannondale has achieved this without having to lengthen the chainstays or offset them to allow for clearance or chainline.

This has been done by using the BB30 Ai standard, as found on the Super-X, Scalpel F-Si, and Habit. By using the 6mm offset and matching crank, which is also on the Super-X, it means the Topstone has plenty of clearance and a super-short back end, being even shorter than the Super-X.

Like Cannondale’s Super-X cyclocross bike, to account for Cannondale’s BB30 Ai standard, it does mean that the Topstone uses wheels with a slightly different dish to standard, which is more symmetric and claimed to be stiffer than a traditional wheel. This differs slightly from off-the-peg wheelsets with a 6mm offset towards the non-driveside.

A bike for all seasons

The new Topstone looks to have all the bases covered when it comes to fixtures and fittings, with three bottle mounts, mounts for a front rack and mudguards, a rear guard and rack, and a bento box mount on the top tube.

The internal ‘direct-line’ cable routing — where all internal cable routing has moulded-in channels — includes internal routing for a dropper post (27.2mm). The bike is designed to allow for up to a 40mm-wide tyre on 700c wheels and 48mm in 650b.

Alongside the new chassis, Cannondale has also developed a new stem and bar, as well as a new carbon wheelset.

Removable fender bridge on road bike
Alongside a wealth of mounts the Topstone also features a removable fender bridge
Cannondale

The stem is a new Hollowgram SAVE unit, which follows the design principles of the stem that debuted on the Synapse but made full production on the SystemSix. The stem eschews a traditional clamp in favour of a cradle that the bar sits on (the bolts thread through the bar), which offers 8 degrees of pitch adjustment.

The stem comes in 80 to 120mm lengths, and Cannondale dealers should have a stock of different lengths to ensure the correct fit.

Unlike the SystemSix, the Topstone’s SAVE carbon bar is designed not to be strictly aero, but more to offer a compliant, vibration-smoothing ride.

The Hollowgram HG22 carbon wheelset is all-new too. This tubeless-ready carbon wheelset has a new rim design with a broad 25mm internal diameter and, as previously mentioned, the wheels are a slightly different dish to standard sets due to the BB standard .

HG22 carbon wheel on road bike
The new HG22 carbon wheels feature a 22mm deep rim that’s a big 25mm wide internally
Warren Rossiter/Immediate media

All of the bikes come with 700c wheels as standard, but the 650b version of the HG22 wheels will be available aftermarket.

Keeping the HG22 wheels in place is a pair of Speed Release axles that we first saw on Cannondale’s SystemSix, and here we think they make even more sense than on the aero-road machine.

The Speed Release uses a 12mm axle that threads into the dropout just like a standard thru-axle, but the lever side features a slotted dropout when you undo the 12mm thru-axle in the normal way. However, the double lead thread on the axle means it’ll tighten, and vice-versa, in five turns rather than the usual 10.

The thru-axle then slides out part way, but it’s anchored via a slot in the hub and a rubber ring on the axle, so it never needs to be fully removed, making refitting or switching a wheel both a quick and clean option because you don’t have to drop your greased-up thru-axle in the dirt while fixing a puncture. It’s another smart addition to what looks to be a very well thought out bike.

Fully-connected digital gravel is now a thing

The Topstone also features the wheel sensor that debuted just a few months ago on Cannondale’s urban Treadwell bikes, and will be available aftermarket.

This wheel sensor was developed in partnership with Garmin and works in conjunction with Cannondale’s own app.

The sensor measures speed, time and distance, and has on-board storage for up to 900 hours of riding. It works with the app or with any head unit via Bluetooth Low Energy (BLE) and ANT+, and it automatically records all rides, running off a CR2032 cell battery with a year’s claimed battery life.

Working with the app, the sensor also instantly logs rides, saving up to 30 days of riding, and can be used during a ride to display distance, speed and calories. It will also tell you how much fuel you’ve saved (as opposed to using a car) and C02 emission reduction.

Connect it to your bike simply by spinning the wheel and then register your bike (for its warranty). You’ll also get bike ‘health’ reminders, so you can add fit and setting details particular to your own bike. It also links to maintenance procedures relevant to your bike, such as brake bleed instructions, and you can register as many bikes as you like.

The app features achievements and goals too, service schedules, technical manuals, links to how-to videos, and an X-ray function that uses an augmented reality screen to show what’s going on underneath the skin of your bike – such as internal cable routing.

The app can be used as a standalone ride log or in conjunction with Strava, or whatever platform you use.

Cannondale Topstone CARBON range

All of the Topstone carbon models share the same Ballistec carbon frame with Kingpin suspension and Ballistec carbon fork, and all come with Cannondale’s new wheel sensor.

Cannondale Topstone CARBON Force AXS

Cannondale Topstone Carbon
The flagship of the new Topstone range is this Force eTap AXS-equipped model
Cannondale

The range is topped by SRAM Force eTap AXS with Hollowgram HG22 carbon wheels, Hollowgram SAVE aluminium stem and SAVE carbon bar with the new wheel sensor.

  • Price: £4,799.99 / $6,500

Cannondale Topstone CARBON Ultegra RX

Cannondale Topstone Carbon
The Ultegra RX-equipped model with carbon wheels
Cannondale

Sitting just below is this Ultegra RX model (46/30 – 11-30 cassette) with HG22 carbon wheels and a new 12-degree flare aluminium gravel bar.

  • Price: £3,499 / $4,900

Cannondale Topstone CARBON Ultegra RX 2

Cannondale Topstone Carbon road bike white background
The Topstone comes in two different Ultegra RX models, one with carbon wheels and this one with WTB i23 tubeless-ready alloy units
Cannondale

The next in line shares the same Shimano Ultegra RX 2 setup but forgoes the carbon wheelset for WTB’s Alloy i23 wheelset.

  • Price: £2,699.99 / $3,250

Cannondale Topstone CARBON Ultegra RX 2 women’s

Cannondale Topstone Carbon
The women’s-specific Topstone comes equipped with Shimano Ultegra RX
Cannondale

The women’s model shares the same spec as the RX2 but features a frame with women’s-specific geometry and a women’s-specific saddle.

  • Price: £2,699.99 / $3,250

Cannondale Topstone CARBON 105

Cannondale Topstone Carbon
The new Topstone carbon starts with this Shimano 105-equipped model
Cannondale

Below the Ultegra models is the base model 105-equipped bike with WTB i23 wheels.

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  • Price: £2,099.99 / $2,700