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Cannondale Synapse Carbon Ultegra Disc



Fast, smooth performance with all the benefits of Shimano's hydraulic disc brakes

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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Fast and smooth performance with all the benefits of Shimano's hydraulic disc brakes with mechanical shifters makes the Cannondale Synapse Ultegra Disc a very attractive bike for the cyclist who likes to ride fast, but doesn't want to race and demands comfort and the option to run wider tyres; it comes with 28mm tyres as standard.

The redesigned Cannondale Synapse was one of the most well received new endurance road bikes last year, so good was it that it scooped our Sportive Bike of the Year award at the end of last year. For 2015 though the change is the adoption of disc brakes, with seven models in the Synapse range coming with disc brakes. (Since we originally published this review the Synapse Disc has gone one better than its non-disc braked sibling by scooping our 2015 Bike of The Year Award and our Sportive Bike of the Year Award.)

Cannondale Synapse Hi-Mod Disc Dura Ace Di2 2018

Buyers Guide to Sportive and Endurance Road Bikes


Ride: Buttery smoothness and plenty of speed on tap

When I rode the Synapse last year I found a "super smooth and comfortable distance bike with rewarding handling and fast performance". The good news with the disc version of the Synapse is that those findings still ring true, but it offers all the advantages of hydraulic disc brakes, making it an even more compelling package as a year-round bike.

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The Shimano RS685 hydraulic disc brakes with mechanical shift levers could just well be the Japanese company's best combination to date, and allow Cannondale to hit a really competitive price point that simply would not be possible with a Di2 groupset. And the disc brakes are wonderful in use, with fantastic power from the 140mm front and rear rotors and all the modulation you need to make full use of the available power in all situations. The lever feel is firm and is always the same, no matter the conditions, speed or steepness of the descent.

Disc brakes are increasingly widespread on endurance and sportive bikes like the Synapse simply because they are free of the UCI's rules, and because the manufacturers reckon the type of people buying and riding these bikes will appreciate disc brakes for real world riding and the variety of conditions such a bike will be used in. In the UK that means plenty of gritty winter riding and it's at this time of year that the disc brakes are a boon, with virtually no maintenance or servicing required, long lasting brake pads and much less cleaning required of dirty rims. This doesn't simply make the Synapse a winter bike, far from it, it's just riding at this time of year more acutely highlights the disc benefits.

In adding disc brakes to the Synapse, Cannondale have lost none of the keen handling of the previous model. There's no hint of an increase in stiffness with the new fork and rear stays, but then the plush 28mm tyres, flexy Fabric saddle and gel bar tape provide so much cushioning that the ride is wonderfully comfortable. Underneath those components the frame offers the same rangy wheelbase that provides great stability, making the Synapse unflustered on even the roughest roads and a really calm place to be.

Key to the Synapse is the geometry changes compared to a race bike like the SuperSix Evo, the longer wheelbase (100.5cm) for the aforementioned stability, plus a taller 18.6cm head tube and slacker head (72.5) and seat (73.5) tube angles. That taller head tube places less strain on your neck and back and there is a wide range of further height adjustment possible. Bike of the Year 2015 Sportive Bike of the Year 2015

There are loads of spacers for a start, though the tall conical headset top cap can be removed. Underneath it is a zero rise headset cap, so you can run the stem much lower than standard. If you do decide to do that you'll need to get the bike shop to trim the steerer tube for you. It's a nice touch by Cannondale and keeps most potential customers for the Synapse happy.

Where the Synapse really succeeds is in balancing the frame and fork stiffness demanded by a cyclist who likes to ride everywhere as fast as possible and stomp up hills, with the comfort and compliance that ensures it is a bike that will satisfy those cyclists wanting a comfortable bike for any adventure you might have planned.

You could ride this bike to work everyday and use it on the Etape next summer, with no changes required. You can slam the stem and get racey on it and ride everywhere as fast as you can. You can do everything on this bike that you can do on a race bike, short of actually lining up for a race (unless you can find one that doesn't apply the UCI rule book). It's an extremely capable bike.

Frame: Cleanly integrated disc brakes

The frame is essentially identical to the regular non-disc Synapse, but there's a brand new fork with the brake hose routed inside the left leg and the brake caliper attached via a post mount. It's very neat, and so it is at the back too, where the rear hose is internally routed until exiting halfway along the chainstay, where the rear brake caliper is fixed into place.

Elsewhere, the frame has all the same styling cues as the regular non-disc version of the frame, and the same SAVE+ (Synapse Active Vibration Elimination) technology. The rear stays and fork legs are sculpted and profiled to provide as much compliance as possible, the seatpost is 25.4mm diameter - to provide more deflection - with the clamp integrated into the top tube to provide exposed seatpost for deflection. And Cannondale have worked their engineering magic in the carbon fibre layup to provide damping qualities in the carbon itself.

Down at the bottom of the seat tube is the unique 'Power Pyramid', a split tube which aims to increase the stiffness at the bottom bracket without the weight penalty of a larger diameter seat tube. Plus it looks pretty cool and is a good talking point on the club ride. There's the same tapered head tube up front and the down tube and top tube are the same as the regular bike. All the gear cables on this Ultegra mechanical shod bike are routed inside the frame, and the result is a very clean, unfettered frame.

The area around the seatstays is clean and uncluttered, and arguably prettier looking than the rim brake version of the same frame. The combination of those different frame features is a bike that is wonderfully smooth and compliant and leaves you feeling a lot fresher after a hard ride on hard roads than a comparable race bike.

The only thing missing from the frame is mudguard mounts. Some manufacturers have managed to squeeze concealed mudguard eyelets onto their disc-equipped endurance bikes (such as the Specialized Roubaix Disc) so it's a shame to see Cannondale not do the same. They're not the only ones to blame, Giant didn't add any to their new Defy either. That limits your options in the winter to a muddy bum or clip-on mudguards.

Build: Hydraulic discs and mechanical gears and competitive price

Certainly £2,500 is a lot of money but this Synapse offers excellent value for money. There are Shimano's brand new RS685 mechanical shifters and hydraulic brake levers, combining hydro disc brakes with mechanical gears, Ultegra 11-speed derailleurs and a Cannondale Hollowgram Si BB30A chainset with FSA 50/34 compact rings partnered to a wide range 11-32 cassette. It's a reliable transmission: the Shimano parts provide smooth gear shifts and the Cannondale chainset shows no lack of stiffness.

Mavic have come to the disc brake party with two new wheels, the Ksyrium Disc and these Aksium One Disc wheels. The Aksium wheels aren't that light at a claimed 1,965g and that does blunt the performance of the Synapse a little, but they proved very durable during the test, and certainly bombproof when I accidentally clattered into a crater of a pothole the other day. The hubs feature Shimano's Centerlock mount to secure the 140mm IceTech rotors in place.

Like the Giant Defy Advanced, the Cannondale uses regular quick release axles which seems to be the choice for most manufacturers at the moment, at least until there has been more development and discussion of a thru-axles standards for road bikes. The quick release skewers did a fine job of keeping the wheels securely in the dropouts, with no brake rub detected at all and wheel changes as easy as any non-disc bike.

One of the big appeals of the Synapse, and most bikes of this breed, is the capacity for wider tyres. Cannondale have fitted 28mm Mavic Aksion WTS tyres and they're supremely smooth and fast-rolling with plenty of traction, a bonus on wet and mud covered country lanes. Just out of interest, and to offer some comparison to the Giant Defy and last year's Synapse, I fitted some 25mm tyres and there was only the smallest drop in smoothness, but the lower rotational weight seemed to make an impact on momentum at higher speeds.

The Synapse is well finished with own-brand aluminium handlebars, with a comfortable compact shape, stem and carbon fibre seatpost. The gel bar tape provides good cushioning for the hands and the Fabric Spoon Shallow saddle is extremely comfortable and a high degree of flex in the base contributes to the plushness of the bike.

On the scales the Synapse, for this 56cm size, weighs in at 8.43kg (18.58lb). That's about on the money for a disc-equipped carbon-framed road bike at present, unless you throw some serious cash at some carbon wheels and finishing kit. There is a weight penalty though, and it's in the region of 700g when compared to the very similarly specced Synapse Ultegra without disc brakes we tested last year.

To put that weight difference into context, because I know some people will be fretting about it, it's roughly the same weight as a full 750ml water bottle. That's all, it's not much really is it? Unless you ride both bikes back-to-back, it's nigh-on impossible to really say you can notice the weight all of the time, but it's when it comes to stopping and slowing that the disc brakes more than justify the slight extra weight. Disc bikes will get lighter with time and development, and those Mavic wheels are one area where weight could be saved, as the Aksium Discs are heavier than the regular Aksium wheels.


The Cannondale Synapse Ultegra Disc retains the same classic ride performance and handling of last year's bike but adds the superb braking ability of Shimano's hydraulic disc brakes coupled to an 11-speed mechanical transmission. It's a brilliant combination and makes the Synapse more fun to ride and more appealing for year-round riding.

The Synapse offers a classy ride, loads of smoothness with enough performance for cyclists who aren't interested in racing but still like to ride fast and challenge themselves, with more than enough speed easily accessible to keep ever die hard racers happy.

It's smooth enough for the harshest roads and comfortable for the longest rides, yet never holds you back when you want to get a shift on. With the disc brakes it's easier to manage that speed, in the dry and in the wet.


Fast, smooth performance with all the benefits of Shimano's hydraulic disc brakes test report

Make and model: Cannondale Synapse Carbon Ultegra Disc

Size tested: 56

About the bike

State the frame and fork material and method of construction. List the components used to build up the bike.

Conquer the northern cobbles. Show chip-seal who's boss. Crush an all-day epic without next-day nightmares. Discover Synapse''the revolutionary balance between raw power and intuitive flex that never steals your speed. Constructed with the flex to give and the snap to go, Synapse lets you rule any road, anywhere. The ideal blend of compliance, rigidity and weight makes for a dream bike that redefines 'endurance". Get out there and let your Synapse fire.

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?

S.E.R.G. SYNAPSE ENDURANCE RACE GEOMETRY: With its slightly taller head tube, slightly longer wheelbase and slightly slacker head angle, S.E.R.G. strikes the ideal balance between pure race positioning and upright comfort. Perfect for long days in the saddle and confident handling on all road surfaces.

SAVE PLUS MICRO-SUSPENSION SYSTEM: The SAVE PLUS Micro-suspension system is a three part system, comprised of the carbon lay-up, the rear triangle and fork, and the seat post and seat tube, all designed to collaborate seamlessly to reduce vibration, improve handling, and increase comfort.

SAVE PLUS MICRO-SUSPENSION SYSTEM (REAR TRIANGLE AND FORK): The frame and fork's carbon layup is designed to optimize high-frequency vibration dissipation, reducing road buzz. The radical helixed shapes of the chain stays and seat stays work in conjunction with the offset dropout fork to allow the wheels to track over imperfections in the road for better handling and control, seated or standing.

SAVE PLUS MICRO-SUSPENSION SYSTEM (SEAT POST AND SEAT TUBE): The elegantly scalloped seat tube and the smaller diameter 25.4mm seatpost are designed to flex together to provide more comfort when seated. The integrated collarless seat clamp allows more of the seatpost to flex than with a traditional clamp.

POWER PYRAMID/BB30A: The seat tube splits asymmetrically to meet a new wider 73mm BB30A bottom bracket, for maximum stiffness with minimal weight.

Frame and fork

Overall rating for frame and fork

Tell us about the build quality and finish of the frame and fork?

Superbly finished frame with smartly integrated disc brakes and internal hose routing.

Tell us about the materials used in the frame and fork?

This Synapse uses regular carbon fibre while the more expensive models use high grade high modulus carbon fibre, the difference in performance is minimal.

Tell us about the geometry of the frame and fork?

Perfectly balanced for all-day riding and flat out blasts chasing wheels.

How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?

There's a large range of handlebar height adjustment with two headset top caps available to tailor the fit.

Riding the bike

Was the bike comfortable to ride? Tell us how you felt about the ride quality.

Impressively comfortable: the flexible saddle, gel bar tape and large 28mm tyres go a long way to making this a really smooth bike.

Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?

Yes when you get the power down and get the Synapse excited, there's evidently enough frame stiffness to match the most demanding cyclists.

How did the bike transfer power? Did it feel efficient?

No flex or squirm detectable when mashing on the pedals.

Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?

It does everything really well, feels docile and easy at lower speeds and when you get animated at higher speeds the Synapse responds willingly.

Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?

The wheels are a bit weighty.

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The drivetrain

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Wheels and tyres

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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.

Anything further to say about the bike in conclusion?

Every bit as good as the regular Synapse, but better.

Overall rating: 9/10

About the tester

Age: 31  Height: 180  Weight: 67

I usually ride:   My best bike is:

I've been riding for: 10-20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo cross, commuting, touring, mtb,


David worked on the tech team from 2012-2020. Previously he was editor of and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes

Add new comment


mark_melb | 7 years ago

To put weight in perspective, I have the Hi Mod all mechanical Dura Ace non disc version of this and it weighs in at 7.14kg in a size 56.

davecochrane | 8 years ago

I'm interested in knowing how you reckon this stacks up to the likes of the Roubaix at an equivalent equipment level - the pricing is certainly a lot more attractive although an Ultegra Di2 option might be nice.  4

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