Cannondale Slice

Every now and then a bike comes along that does things differently.Cannondale’s new Slice is a bold attempt to change the way we look at tri bikes. We take it out for a spin to get the full perspective.

Unless you happen to be particularly fond of wind tunnel charts, bike launches can be a somewhat tedious process. So at the launch of the 2015 Cannondale Slice we’re bracing ourselves for the standard torrent of dry aerodynamic information and marketing claims. But it never arrives.

Much to our surprise and delight, Cannondale has taken a different approach to its update of the Slice – the original version of which won Ironman World Championships in the custody of Mirinda Carfrae and Chrissie Wellington – and it’s a much more triathlete-friendly and, more importantly, age-grouper friendly one.

The Slice is a triathlon bike, not a TT bike. That might sound like nitpicking, but it’s an important distinction. A TT bike is designed with an emphasis on aerodynamics and speed, whereas a triathlon bike also has to take into account comfort, fit and the ability to run after the five-plus hours in the saddle for an Ironman bike leg. If you’re riding a 10-mile TT you can, to a certain extent, contort yourself into the most aerodynamic position you can manage and worry about the consequences after 20mins of suffering. If you try the same in an Ironman, you won’t even make it to T2.

David Devine, Cannondale’s product manager for the Slice project has even gone so far as to describe the bike industry as having ‘tunnel vision’ when it comes to bike design, becoming obsessed with wind tunnel performance often at the expense of other factors like comfort, handling and weight. Which is why Cannondale has adopted a more balanced approach to performance that’s described as RealTri technology, with the tag line ‘go faster, stay fresher, ride easier’.



If you check out the chain and seatstay designs on the Slice, you’ll notice how skinny they are and how much more they have in common with road bike stays than other tri bikes. This was a big design decision for Cannondale, because vertical seatpost designs don’t have as much scope for flex as slanted ones on road bikes, so the comfort has to come from somewhere else. The thin profile of the stays also means that, although they’ll sacrifice some aerodynamic benefit, you’ll gain an awful lot in comfort, as they’re ultra-compliant and have a far greater range of deflection. The design is called Aero Save Micro-Suspension and allows for between 2.5mm and 4mm of deflection under increasing loads. What that translates to for the rider is a bike that feels a lot smoother, to the point where Cannondale makes the bold claim that the Slice is actually more compliant than a lot of endurance road bike frames on the market.

The comfortable back-end is paired up with the Aero Save fork, complete with offset dropouts and a directional carbon layup similar to the one used in the SuperSix Evo frame. It’s significantly less stiff than the old Slice’s fork, but has a higher stiffness-to-weight ratio and so should offer a pleasing compromise between precise handling and comfort.

Moving on to the frame design, Cannondale has used Truncated Aero Profile (TAP) tube shapes. These are basically aerofoil tubes rounded off at the back instead of following through and finishing in a point. This provides a double advantage of keeping the weight down and providing less side surface area for the wind to hit, making the bike more predictable in crosswinds. Weight-wise, Cannondale has done an amazing job of making the high-mod version of the Slice frame just 1,020g, lighter than many road bike framesets. Of course, the truncated tubes do mean that the Slice loses out in the wind tunnel to the likes of the Specialized Shiv or Cervélo P3, but the losses aren’t as huge as you’d think and come down to fewer than 10 watts of drag at a zero-degree yaw angle.

To put that in perspective, the difference between a rider on the bullhorns and in the aero position is far greater than 10 watts – having the ability to get into a sustainable position is, in reality, far more valuable than stressing over the drag of the bike that you’re riding. Given that the rider accounts for roughly 80% of the drag, quibbling about a few watts really is by the by unless you’re fast enough that such marginal gains matter.

Another nice touch is that every model of the Slice, from the top-of-the-range Black Inc right down to the Shimano 105 version, comes equipped with 25mm tyres for an added bit of comfort. Even better, they have clearance for up to 28mm, so you can go really big if you want yet more comfort. With most recent wind tunnel tests suggesting that there’s certainly no aerodynamic loss from using 25mm tyres rather than 23mm (and possibly even some gain), there’s no reason to go as thin as possible.



From a triathlete’s perspective, fit is possibly the most important aspect of a tri bike. A machine that allows you to stay comfortable, aerodynamic and produce the optimal amount of power over the gruelling bike leg is the ideal that everyone is striving for.

With that in mind, Cannondale took the data from thousands of bike fits undertaken by their partner, Guru, on real triathletes -– that is, age-groupers and not just pros – and analysed them, using that data to dictate the geometry for the Slice. The result was what they call ‘real tri geometry’, optimised around a steep 79° seat angle that gives an effective range of 77-81°. That geometry aims to enable riders to find the best combination between an open hip angle, an aerodynamic position and comfortable  weight distribution. Added to that, every model of the Slice comes with a low bottom bracket and short cranks – 165mm for 44-54cm frame sizes and 170mm for 57-60cm – which allows the hip angle to open out further and also has the side-effect of creating a lower centre of gravity and therefore delivering handling that’s even more stable. The other by-product of the lower bottom bracket/short cranks combination is that both the seat height and the stack height move down, meaning the rider is already more aerodynamic.

Frankly, it’s a pretty bold move from Cannondale because it’s going against the trends of almost all its competitors and rivals. It’s relying on the bike-purchasing public to buy into this philosophy in the face of contrary information from countless other big brands.



Our test route takes us from the city down to Maroubra and La Perouse in Sydney’s east, taking in a national park circuit popular with weekend riders. Despite Sydney’s changeable weather it’s a hot day, and though the hills involved are mostly undulating there are enough short, sharp elevations to work up a sweat.

The test bike we piloted was the Ultegra Di2 edition with the 1,020g frame. Straight away we notice how astonishingly light the bike feels. Weight-wise it’s genuinely akin to riding a road bike and accelerations are rewarded quickly and dynamically. This transfers over into manoeuvrability as well: the subtle little movements that you get used to on a road bike – like flicking round a pothole or changing line sharply – which are usually markedly less sure on a tri bike, are more than confidence-inspiring on the Slice, if not quite at road bike levels.

The short, steep climb up from Little Bay is definitely a test for a tri bike, as most tend to err on the side of frustrating when the gradient kicks up at a level with which you can’t cope on the tri bars. But this is another area where the weight of the Slice becomes noticeable, and it never feels like you’re dragging the bike with you. That’s not to say that we’d necessarily choose to ride uphill on it, but first impressions suggest that if you were doing a hillier race and wanted to ride a tri bike, the Slice would get the job done – and done well. Out onto fast, flat terrain in the shadow of Kingsford Smith Airport and the stability of the Slice really becomes noticeable. It’s a large, open space where the wind gusts hard and the smaller side-on cross section of the bike makes it comparatively easy to handle.

As Cannondale alludes to in its own literature, we suspect that when it comes to straight-line speed the Slice does give something away to competitors, like the Cervélo P5 or Felt’s IA. That’s purely subjective based on the speeds  we were travelling and the feel of the bike at those speeds, but in Australia, where conditions can be windy from time to time, we speculate that a lot of triathletes might opt for something that could assure them of an easier ride when the weather turns rough.Comfort was the big factor we were keenly aware of, given Cannondale’s claims about the smoothness of the ride, and we were rather impressed after the 2:30hr test. On flat, smooth roads pretty much any bike can feel comfy, but the ride home along Anzac Parade can often resemble a demilitarised zone from the amount of debris there is lying around.

The Slice handles it all superbly, even when hitting bumps in the road that jolt you to your core. The seatpost is noticeably subdued, with zero teeth-chattering moments – not something we can say of many tri bikes. Too many manufacturers seem to forget that a triathlon bike ride is followed by a run, so it doesn’t matter if you have the most aerodynamic ride available when you’re sitting at the side of the road contorted with back spasms 15mins after leaving T2. Given the choice, we’d go for comfort every time.

Ultimately, we’d like even more riding time to deliver a definitive verdict on the Slice, but our first impressions were fantastic, and we can’t wait to get our hands on one again and chew up more kilometres in race conditions.

Price: $6,299 RRP

Specifications and sizing:


Looking for something else? Read our review on the Cervelo P3.