The Cannondale Synapse Carbon 4 balances stiffness and comfort superbly, surprising me from the word go with its incredibly responsive frame. It’s good value, too, when you consider how future-proof it is, with wider tyre clearance than its rivals, giving it the ability to become an allroad gravel machine for adventures off the beaten path.
The all-new Synapse shares many of its design elements with the current SuperSix Evo. Cannondale even views the new Synapse on the same level as its race bike – and claims it melds WorldTour-level aerodynamics and stiffness with generous tyre clearance, compliance and features that appeal to the general rider.
Cannondale Synapse Carbon 4: Ride
I’ll admit I wasn’t expecting any fireworks from the Synapse in the performance department when it first arrived for testing, but it surprised me from the first ride. The handling feels a lot like the current SuperSix Evo, and there are hints of the SuperX in there, too, its race-focused gravel bike – particularly in the way it deals with vibrations and smooths out broken roads.
Cannondale says it has increased stiffness in the head tube and bottom bracket, while improving compliance by 20% over its predecessor to enhance overall performance. The frame is incredibly responsive, balancing stiffness and comfort superbly. Despite a longer wheelbase and chainstays, the Synapse is still pretty nimble, eager to respond to steering inputs, but still very predictable on descents and flowing sections of tarmac.
The stock 32mm tubeless-ready Rubino tyres are just brilliant. While converting the tyres to tubeless is a non-negotiable for me these days, I elected to use the stock wheel and tyre setup for the duration of my testing. Based on the bike’s weight, I didn’t drop the tyre pressures as much as I usually do for tube-type setups, but still went as low as 60psi for the front and 65 for the rear for my 62kg weight, which seemed to provide a good balance between comfort and speed.
Speaking of weight, it was only on very steep climbs of five minutes or more that I felt the full wrath of the 9kg, but for the most part I didn’t think the bike was holding me back – it carries momentum impressively well and maintains its speed very well. Thankfully, it’s been specced with a 50/34T chainring and 11-34T cassette, which ensure ample speed on the flats without crazy-high cadences, and a decent spread of gearing for when things get particularly steep.
Despite its alloy construction, the cockpit is well considered, and at 38mm wide represents a sweetspot in terms of balancing ergonomic performance with aerodynamics. While the stack and liberal stem spacers did raise my hand position and create a slightly more upright riding position than I’m used to, I very much enjoyed it thanks to the 381mm reach figure. You can still get fairly aero and not feel like the slightly more upright position is costing you – it feels natural and comfortable.
Cannondale Synapse Carbon 4: Frame
The new Synapse cuts a striking appearance and retains much of Cannondale’s current design DNA, with full integration taking centre stage. It bears a strong resemblance to the current SuperSix Evo, as evidenced by the narrow head tube, boxy down tube, top tube, and dropped seatstays.
Our Synapse Carbon 4 test bike might be one model up from the bottom of the range, but the richness of its Metallic Red paint scheme bolsters its perceived value with head-turning appeal (it’s also available in an off-white Chalk). It all looks very premium and refined.
The geometry numbers are not too far removed from the previous-generation Synapse. It has the same 570mm stack height and 381mm reach as before, but the head angle is down from 73 to 71.5 degrees. For context, the SuperSix Evo has a stack and reach of 555mm and 384mm, along with a 71.2-degree head angle.
All Synapse models come as standard with 32mm tyres, but there’s space at the rear for up to 42mm and the ability to go as wide as 48mm at the fork. It’s no gravel bike and doesn’t profess to be one, but I suspect some owners will attempt to shoehorn wider tyres than stated in the quest to create the ultimate allroad machine.
The increased tyre clearance has resulted in a 39mm increase in the wheelbase (1,026mm) and a 3mm increase in trail (61mm), as well as longer chainstays (up 15mm to 425mm), in size 54cm.
There are mounts for mudguards and a small top tube bag, to go with the usual bottle cage bosses inside the triangle, plus StashPort down tube storage under the bottle cage – the system already used on the Topstone Carbon.
It can store tools, a tube and a hand pump, freeing up your pockets. (SmartSense-equipped Synapses use this space to store the battery.)
Cannondale Synapse Carbon 4: Finishing kit
As one of the lower-end models in the range, the Synapse 4’s specification list isn’t lavish but it is still well appointed. Bar the frame and Cannondale C1 Aero 27 seatpost, there’s not much in the way of carbon fibre componentry, but the alloy Vision Trimax Aero handlebar and Cannondale C1 Conceal stem are ideally suited for the job at hand, as is the Fizik Vento Argo X5 saddle.
The seatpost is shared with the SuperX, CAAD13 and SuperSiX Evo Gen 3. Unlike the previous edition, SmartSense (comprising an integrated front light, rear light, and rear radar with a battery in the down tube) is now only available on three of the eight models: the range-topping Lab71, Carbon 2, and Carbon 3.
In a move similar to the automotive industry, Cannondale has introduced part sharing across its drop-bar offerings, so the Synapse now features the same threaded BSA bottom bracket and Delta steerer first seen on the current SuperSix Evo, as well as the same thru-axles, rear hangers, and stems.
At the heart of the bike lies the rock-solid and proven Shimano 105 Di2 groupset, featuring sharp hydraulic braking and refined shifting. Sharing its basic architecture and functionality with Ultegra and Dura-Ace, it operates similarly to its pricier siblings, just with a slight weight penalty.
The Synapse Carbon 4 employs a pair of rather heavy but durable alloy DT Swiss 470 rims. Wrapped in 32mm Vittoria Rubino Pro IV tyres, it’s all hardy rolling stock that brings peace of mind and reliability to the package.
Total system weight, however, is not the Synapse Carbon 4’s strong point – we’re talking 8.95kg without pedals. That said, there’s scope to cut the lard easily; new wheels, tyres, rotors and a carbon-railed saddle will drop the overall figure by as much as 1kg.
Cannondale Synapse Carbon 4: Value
Cannondale has done an incredible job with the new Synapse, and this is reflected throughout the range. It is relatively heavy, but this comes down to the alloy DT Swiss 470 rims, which can be sorted out easily if you’ve got a few bob lying about.
At £3,995 for a carbon-framed endurance bike, with Shimano 105 Di2 electronic shifting coming as standard, it’s cheaper than its nearest rivals.
The biggest of those comes in the form of the Canyon Endurace CF SLX 7 Di2. At £4,199, it is pricier than the Synapse, with the same Shimano 105 Di2 groupset, and though it gains carbon wheels – a wheelset upgrade that would significantly add to the price of the Synapse – its 35mm tyre clearance comes up significantly short.
Likewise, the Trek Domane SL6 Gen 4 might have better tyre clearance than the Endurace (38mm), but it can’t match the 42mm of the Synapse, nor its price – the Domane costs £4,175 in 105 Di2 spec. The Domane is also fairly heavy at 8.9kg, but again, this comes down to the aluminium wheels.
Read our guide to the best endurance road bikes for more options.
Cannondale Synapse Carbon 4: Conclusion
The Synapse Carbon 4 is one of my favourite bikes of the year. It belies its nearly 9kg weight with its balanced geometry, aero-optimised carbon frame and well-sorted gearing. It took me by surprise, and probably will do many others, too. While there are better-specced Synapse models further up the range, I expect the Carbon 4 to be the volume seller and the bike that puts Cannondale back on the radar of the general rider.
Verdict
A belter of a bike with a price tag to match
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road.cc test report
Make and model: Cannondale Synapse Carbon 4
Size tested: 54
About the bike
List the components used to build up the bike.
Frame and fork: Carbon frame and fork, Proportional Response construction, integrated cable routing, downtube Stashport.
Groupset: Shimano 105 Di2
Chainset: Shimano 105 50/34T with 172.5 cranks
Cassette: Shimano 105 11-34T
Brakes: Shimano 105 7170 hydraulic disc, 160/160mm RT70 rotors
Wheels: DT Swiss R470
Tyres: Vittoria Rubino Pro IV 32mm
Handlebar: Vision Trimax Aero Alloy
Stem: Cannondale C1 Conceal, Alloy, 31.8, -6°
Grips: Cannondale Bar Tape, 3.5mm
Saddle: Fizik Vento Argo X5, 140mm
Seatpost: Cannondale C1 Aero 27 Carbon, SmartSense compatible
Tell us what the bike is for and who it’s aimed at. What do the manufacturers say about it? How does that compare to your own feelings about the bike?
Cannondale says the bike is for “comfortable high-performance road riding, long-distance missions, fast group rides”.
“Synapse Carbon 4 runs Shimano 105 Di2 for a shifting experience that feels straight off the pro tour, minus the bank loan. The frame delivers that signature Synapse ride quietly fast, endlessly composed, and plays nice with wide tires, fenders, and long days. Call it the sweet spot between Sunday speed and weekday practicality.”
Where does this model sit in the range? Tell us briefly about the cheaper options and the more expensive options
The Synapse Carbon 4 sits second from the bottom in the range. The Carbon 5 is the entry-level model, while the Synapse Lab71 SmartSense spearheads the eight-bike lineup.
Frame and fork
Tell us about the build quality and finish of the frame and fork?
The bike is built to a high standard and feels like it’s of a much higher price point.
Tell us about the materials used in the frame and fork?
The frame and fork are constructed from carbon fibre.
Tell us about the geometry of the frame and fork?
The geometry is not racy – it uses endurance angles to promote comfort and performance over long distances.
How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?
Stack and reach are spot on for this type of bike, hitting the sweetspot as far as endurance bikes go.
Riding the bike
Was the bike comfortable to ride? Tell us how you felt about the ride quality.
Yes. The ride quality is very comfortable, but this doesn’t affect performance and responsiveness.
Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?
Cannondale says it has increased stiffness in the head tube and bottom bracket, while improving compliance by 20% over its predecessor to enhance overall performance.
How did the bike transfer power? Did it feel efficient?
Yes.
Was there any toe-clip overlap with the front wheel? If so was it a problem?
No.
How would you describe the steering? Was it lively neutral or unresponsive? Neutral.
Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?
Handling is pretty sharp despite the longer wheelbase and chainstays, and this allows you to descend and corner with confidence thanks to the surefootedness provided by the wheelbase.
Which components had the most effect (good or bad) on the bike’s comfort? would you recommend any changes?
The wheels are not the greatest set out there. As alloy options, they are very heavy, but can be upgraded over time to improve acceleration, ride feel and comfort.
Which components had the most effect (good or bad) on the bike’s stiffness? would you recommend any changes?
An affordable pair of carbon wheels will not only drop the weight but also improve the performance and ride feel.
Which components had the most effect (good or bad) on the bike’s efficiency? would you recommend any changes?
The carbon frame, Shimano 105 Di2 groupset, and 38cm handlebar made for an exceptionally sharp and compliant machine.
The drivetrain
Wheels and tyres
Controls
Your summary
Did you enjoy riding the bike? Yes
Would you consider buying the bike? Yes
Would you recommend the bike to a friend? Yes
How does the price compare to that of similar bikes in the market, including ones recently tested on road.cc?
The Cannondale Synapse Carbon 5 is the cheapest option among its closest rivals with Shimano 105 Di2 groupsets. Okay, the Canyon Endurace CF SLX 7 Di2 gets carbon wheels for its £4,199 RRP, but it lacks the tyre clearance of the Synapse. The same goes for the £4,175 Trek Domane SL6 Gen 4: it also has alloy wheels, and the spec is the same, but the tyre clearance is not as generous as the Cannondale.
Use this box to explain your overall score
I think Cannondale has done an incredible job with the new Synapse: it’s stiff but comfortable, nimble when you want it to be but also predictable. It’s also a little cheaper than rivals with the same groupset, but what really sets it apart is the extra tyre clearance, adding versatility and future-proofing to the mix. Overall, it’s excellent.
About the tester
Age: 0 Height: 175cm Weight: 62kg
I usually ride: My best bike is:
I’ve been riding for: 10-20 years I ride: Every day I would class myself as: Semi pro
I regularly do the following types of riding: road racing, time trialling, mtb, Time trial, gravel and Elite Cycling eSports
9 thoughts on “Cannondale Synapse Carbon 4”
£4,000 for a 105 carbon bike
£4,000 for a 105 carbon bike with naff wheels and tyres
And 9kg.
And 9kg.
Quote:
Happened to be looking recently, as a friend was considering it and asked my opinion, at the Dolan Tuono endurance bike, full carbon with 105 Di2 and a Mavic Cosmic S42 carbon wheel upgrade for a whisker under £2500, so that statement really isn’t accurate. Sure there are plenty of others with the same spec or better that beat the Synapse on price.
The Tuono is an open mould
The Tuono is an open mould frame though.
Cannondale have really lost
Cannondale have really lost their way in the paint schemes and logos for their bikes.
They used to have awesome paint jobs but this one looks boring and with the main Cannondale logo looking like it’s been chosen by someone with zero design skills.
That picture of the storage
That picture of the storage bag is the fugliest detail pic of a bike I recall ever seeing. And the entire bike does not fair much better. But it seems to prove that looks and ride quality are two different things on a bike. Furthermore, at least it doesn’t look like a boring Canyon that everybody else is riding
This bike is a good example
This bike is a good example of why people buy Canyon instead. In the U.S. it’s over $1000 more with cheap alloy wheels than a very nice Canyon Endurace with carbon wheels and carbon bar and stem. A few bob more for carbon wheels? Hardly and that’s just a strange thing to say. It’s even $600 more than a Roubaix which is a far better endurance bike. Don’t get me started on the Domane though with it’s high price and creaking and slipping setapost.
Worrying about aerodynamics is silly for almost everyone and the bars are too narrow leading to discomfort on what is supposed to be an endurance bike. But it’s a marketing point for bike companies and gives reviewers something to write about. It’s just a fad.
The rear cassette should go to 36.
I lost a lot of interest in Cannondale after the smart sense debacle and I started buying Cannondales in the mid-80’s and have owned several Synapse’. It would take a lot for me to buy one again. Cannondale has really lost the plot and this bike and price shows they haven’t learned a thing. One other thing. I think I’m pretty open to frames looking different these days but the proportions of this one just look off to me.
I saw the new Synapse in the
I saw the new Synapse in the flesh the other day.
The seat tube is strange – there’s huge space between it and the rear wheel and it’s so thin the curve looks old.
in contrast boxy is an understatement for the down tube – it really is very wide indeed.
And I wasn’t so keen on the storage cover, which is raised from the down tube.
I could be biased as I own one but the latest gen BMC Roadmachine does it better.
£4,000 isn’t great value (then again neither was my bike) – direct competitor Canyon beats it hands down. And new wheels won’t be a few bob as the journalist suggests (what planet is he on?).
if it rides amazingly, though, perhaps the above can be overlooked.
£4k for a 9kg bike with 105.
£4k for a 9kg bike with 105. I know prices have gone mad the last few years, but that seems like poor value to me.