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Cannondale SystemSix Ultegra review

15 Dec 2020

Ultra-efficient aero racer with blistering performance and enviable comfort

Cyclist Rating: 
Rapid handling • Proven aero performance • Incredible wheelset • Top comfort • Surprisingly adept climber • An altogether thrilling ride
A few 105 groupset components lurking in the shadows

Bike manufacturers are experts at claiming performance benefits only to back them up with terms like ‘wind-tunnel-developed’. But the Cannondale SystemSix Ultegra puts its money where its mouth is, with the publication of a 52-page white paper which breaks down the science behind why Cannondale proudly claims this is ‘designed to be the fastest road bike on the planet’.

This document lays out the detail behind demonstrable claims. Namely, that the Cannondale SystemSix Ultegra is faster than a dedicated lightweight climbing bike on gradients up to 6%; it saves you up to 50W at 30mph; it gets you to the finish line of a 200 metre sprint four bike lengths ahead of anyone else putting in an equivalent 1,000W effort; and that if you were spinning at a ‘recovery effort’ down a 5% descent, a rider on a lightweight climbing bike would need to put out 300W to keep up.

Did someone say ‘fastest bike on the planet’?


Dripping with six appeal

Cannondale calls this the ‘SystemSix’ because each of its six major components is optimised for speed. So, that’s the frame, forks, seatpost, stem, handlebar and wheels.

The kamm tail-profile carbon frameset and fork is said to generate areas of ‘quiet air’, especially behind the seatstay-seat tube junction and head tube.

Buy the Cannondale SystemSix Ultegra from Tredz now

The seatpost is an aero-profile carbon unit, adjusted beneath the junction of the top tube and seat tube with a 4mm hex key; the carbon handlebar is flat-topped, the aero stem segues neatly into profiled spacers; and the Vision SC55 carbon clinchers on which the SystemSix rolls have a 55mm section rim.

It’s built for speed, and it feels quick on the road – in pretty much every situation.


On the up and up

It might seem unusual when discussing an unashamedly aero road bike to focus first on climbing, but this is where the shock hits hard.

Riding the Cannondale SystemSix up the first climb of my first ride reveals one of the big surprises up its carbon sleeve: this 8.48kg racer climbs better than my old Ritte Ace, which I’d built to come in on the UCI weight limit of 6.8kg.

Given the Vision SC55 wheelset on the Cannondale weighs in just north of 2kg with tyres, tubes and thru-axles, credit needs to be given to the slipperiness of the bike’s components as well as the efficiency of the drivetrain.


On shallower climbs, I didn’t have a need for the smaller, 36-tooth chainring, the HollowTech chainset’s 52-tooth ring combining nicely with the Shimano Ultegra rear mech and 11-30 Shimano 105 cassette.

This array of gears, as well as the chain, are the only two Shimano elements which shy away from the Ultegra approach, presumably as a cost-cutting exercise that isn't easy to discern with the naked eye.

Buy the Cannondale SystemSix Ultegra from Tredz now

Specifying Ultegra here would have shaved a few more grams off the overall bulk but likely added to the bike's retail price.


I’m the rocket man

Cannondale might claim that you’ll only need to spin the cranks to enjoy rapid downhill progress, but it’s unlikely you’ll take it easy for long.

Speed freaks need apply… The SystemSix picks up enough speed downhill to coast alongside my riding partner who’s four stone heavier than me, when usually – holding the ultimate trump card of gravity – he’d disappear down the road.

Select the big ring and get the power down and this bike conjures images of lengthy descents in the Atlas Mountains: accelerate, brake, hairpin, out of the saddle, accelerate, repeat…


A 73° head tube angle helps ensure the steering is as rapid as the acceleration. It’s hands-down the most exciting bike I’ve ever pointed down a hill.

And the hydraulically actuated Ultegra callipers grip 160/140mm Ultegra rotors confidently in even the rainiest conditions, if with a little squeal when damp.

Trifling matter though it is, some riders might not appreciate the incredibly noisy freewheel soundtrack when coasting. Personally, I reckon it just sounds more ‘pro’…


Keep them dogies rollin’

Little known Rawhide fact: it’s ‘dogies’ – as in orphaned calves, not ‘doggies’. Anyway…

Get the Cannondale SystemSix on to flat or rolling terrain and you’d be forgiven for asking where in the frame the motor is hidden.

Find the sweetspot somewhere halfway up the 11-speed 105 block and a five-mile stretch of lumps and bumps, false flats and moderate descents is dispatched in a flurry of pedalstrokes, the occasional out of the saddle injection of pace, and only two or three gears.

Sit behind your riding partner and you’ll have to sit up to increase the wind resistance just to avoid rear-ending them.


The Vision SC55 wheels really come into their own in these conditions. Their 19mm internal profile and 25mm external diameter accepts 25mm Vittoria Rubino Pro tyres in a way that ensures the tyre’s inflated diameter doesn’t exceed that of the rim, for optimum aero efficiency (ie, less drag).

You might baulk at the potential for ‘all the gear and no idea’ afforded by this wheelset’s fitment, but I’m here to tell you: it doesn’t matter.

Have fun on your bike – that’s what it’s for – and your mates will be laughing on the other side of their faces when you’re whomping by them on your deep sections. What’s more, you’ll be ripping their legs off in comfort.


The carbon seatpost and handlebars translate little in the way of road vibrations, while the tyres smooth the way.

A snub-nosed Prologo Dimension STN NDR saddle distributes pressure evenly and is deeply padded.


Believe the hype

The Cannondale SystemSix is that rare beast of a bike: although I’m not going to translate the scientific report behind its performance, I am going to tell you it fully lives up to its brief.

Buy the Cannondale SystemSix Ultegra from Tredz now

I can’t remember a bike that made me feel this quick for this little relative effort, and I have absolutely no problem with being ‘that guy’ rolling around on 55mm deep sections through winter.

The SystemSix is a bike that’s too good not to ride all the time, too addictive to consign to the garage for winter. It’s a pure-bred race bike that’s suitable for everyone. And I never thought I’d write that.


Frame BallisTec carbon frame and fork
Groupset Shimano Ultegra
Brakes Shimano Ultegra, hydraulic discs, 160/140mm rotors
Chainset HollowGram OPI SpideRing, 52-36
Cassette Shimano 105, 11-30
Bars HollowGram KNØT SystemBar, carbon
Stem HollowGram KNØT
Seatpost HollowGram 60 KNØT, carbon, 330mm
Saddle Prologo Dimension STN NDR
Wheels Vision SC55 carbon clinchers, Vittoria Rubino Pro Bright Black tyres, 700 x 25c 
Tyres Schwalbe One TLE 30mm
Weight 8.48kg (size M)

All reviews are fully independent and no payments have been made by companies featured in reviews


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