Cannondale Synapse Carbon Disc Dura-Ace review

Just about as smooth as you can get without suspension

Our rating 
4.0 out of 5 star rating 4.0
GBP £3,999.00 RRP | USD $4,999.00

Our review

High-value, high-comfort endurance bike
Buy if, You want one of the smoothest endurance road bikes on the market — without any funky suspension or moving parts
Pros: Incredibly smooth ride, top-shelf Dura-Ace 9120, good price
Cons: Heavy wheels aren't on par with the excellent frameset and group
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The first few times I rode this Cannondale Synapse, I pulled over to check if my tires were going soft. Even after topping them up immediately before the ride. That’s how smooth this bike is.

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This particular build, the Synapse Carbon Disc Dura-Ace, is also great value. How many other bikes with Dura-Ace 9120 can you name for under £4,000 / $5,000? 

But there is always a catch, right? Following Keith Bontrager’s enduring maxim — “light, strong, cheap; pick two” — the Synapse Carbon Disc Dura-Ace achieves an excellent ride, a Dura-Ace group and a great price by using some tanker wheels and a few substitute parts, such as an Ultegra cassette and XT rotors.  

That silky ride, though

I’ll save you the full spiel on Cannondale’s SAVE micro-suspension concept, but I will say that evidence of engineered compliance abounds in this bike. Riding on this bike compared to a normal, rigid carbon frame with the same tires and air pressure is a palpably different experience. 

Where the bike shines brightest is at slow to normal riding speeds. Hitting holes, rocks and cracks at 20mph and slower feels muted, like you’re watching a movie of the road but actually riding the rollers. 

Despite the plush ride, pedal efficiency is high. If there is any lateral flex in the rear triangle, I can’t feel it. As noted (below), the inertia of the wheels detract a bit from the frame’s snap.

Three primary factors contribute to the buoyant ride: a carbon frame designed to flex horizontally, a skinny 25.4mm seatpost with an even skinnier setback perch, and, of course, the 28mm Vittoria Rubinos.

A few factors contribute to the Synapse's smooth ride, including flex zones engineered into the frame that Cannondale calls SAVE micro-suspension
A few factors contribute to the Synapse’s smooth ride, including flex zones engineered into the frame that Cannondale calls SAVE micro-suspension
Ben Delaney / Immediate Media

Cannondale says the seat tube has built-in flex, which it may well have, but it’s easier for me to comprehend the give in the whisper-thin seatstays. Cannondale has been using the flattened design on stays for a while with many bikes. The SuperX cyclocross bike uses the concept on the chainstays to great effect, while keeping a solid lateral platform.

The narrow post also has visible give. Standing next to the bike you can lean on the nose or tail of the saddle and watch it move. How much of this is the narrowed upper section of the post versus the whole post versus the entire frame/post package? I have no idea. But the end result is simple — the bike is comfy on rough roads.

Cannondale doesn't have a monopoly on skinny seatstays, but that doesn't make them any less effective at soaking up bumps
Cannondale doesn’t have a monopoly on skinny seatstays, but that doesn’t make them any less effective at soaking up bumps
Ben Delaney / Immediate Media

I did notice that high-speed bumps weren’t dissipated quite as well. On descents, for instance, cracks in the pavement that the bike would absorb at lower speeds sent sharp shocks up through the bike. 

The geometry is road endurance, meaning a slightly taller head tube and slightly shorter top tube than an all-out race bike. This set-up fits most riders well.

Almost complete Dura-Ace 9120

Shimano has four Dura-Ace groups now and it’s hard to keep track of which is which. The 9120 group employed here is the hydraulic-brake / mechanical-shift version. I generally love most Dura-Ace products, so you won’t get many complaints out of me here.

The hoods do have bulbous top ends to them (the 9170 hydraulic / Di2 levers are hard to distinguish from the all-mechanical 9100 models), but the area you wrap your hands around is normal sized.

Shimano's new hydraulic-brake/mechanical-shift Dura-Ace 9120 levers are a bit larger than all-mechanical levers, but not absurdly so
Shimano’s new hydraulic-brake/mechanical-shift Dura-Ace 9120 levers are a bit larger than all-mechanical levers, but not absurdly so
Ben Delaney / Immediate Media

The Dura-Ace hydraulics are powerful, smooth and reliable. As a tester, going back and forth between bikes with Dura-Ace R9170 hydros and rim brakes — especially on carbon wheels — is eye-opening. And in the rain, it’s downright comical.

Shift action is smooth and crisp, with Shimano’s one-cog-down, up to three-cogs-up rear shift logic on the cassette. The front derailleur can be trimmed for chain line, and shifts flawlessly on Cannondale’s Spider rings. 

Speaking of those Spider rings, Cannondale uses its Hollowgram Si cranks instead of Dura-Ace 9100. I don’t feel like this is a major setback, more of an aesthetic preference, really. And the 50/34 Spider rings paired with the 11-30t cassette make steep hills and big mountains alike much less daunting.

Cannondale's Hollowgram Si crank with Spider rings is hard to miss
Cannondale’s Hollowgram Si crank with Spider rings is hard to miss
Ben Delaney / Immediate Media

Cannondale uses an Ultegra cassette, which is cheaper and heavier. I have to say, though, the Ultegra cassettes aren’t prone to the creaking that some Dura-Ace models can get at the rivets. (Some Dura-Ace cassettes even cracked between the cogs, but Shimano says this problem has been fixed.) In any event, you’re gaining a few grams at the cassette.  

Lastly, the rotors are Shimano XT RT81s instead of the full-Gucci Dura-Ace RT900 black models. Just another little cost saver.

Dura-Ace flat-mount calipers and 160/140mm rotors mean stopping is perfectly controlled, always
Dura-Ace flat-mount calipers and 160/140mm rotors mean stopping is perfectly controlled, always
Ben Delaney / Immediate Media

Wheels, tires… and room for the future

So, about those tanker wheels. The Fulcrum Racing 500 Disc wheels are perfectly fine, but Dura-Ace level they most certainly are not. 

At north of 1,600g with a 26mm rim height, they just don’t accelerate like wheels with lighter rims do. The cost for these would probably be in the the £200 / $250 range, but they aren’t an aftermarket wheel. 

Don’t get me wrong, Fulcrum makes quality wheels that will last for a long time. But these wheels just can’t keep up with the incredible quality of the Synapse Carbon frameset and Dura-Ace group. 

The bike comes with 28mm Rubinos, but there is plenty of room for up to 32s
The bike comes with 28mm Rubinos, but there is plenty of room for up to 32s
Ben Delaney / Immediate Media

Similarly, the Vittoria Rubino Pro clinchers are good workhorses, but they won’t win any awards for low-rolling resistance or supple feel. They will keep you rolling for a long time with a low chance of a flat, though, thanks to the tough puncture protection.

The good news here is that tires are easy to change and that the Synapse has clearance for up to 32mm balloons. Tires that fat on this frame? You’d be floating on cloud nine.

Cannondale and Fabric finishing kit

Besides the Hollowgram crank, Cannondale also does the cockpit. A stem is a stem, and the bars are comfortable enough, although the round tops seem a little quaint in a year when so many brands are embracing the pressure-distributing flattened tops. But the fork and frame do such a fantastic job that a shaped bar isn’t needed.

The integrated Garmin mount is a clean touch, although not as perfectly straight or rigid as a metal mount from K-Edge
The integrated Garmin mount is a clean touch, although not as perfectly straight or rigid as a metal mount from K-Edge
Ben Delaney / Immediate Media

The integrated Garmin mount that comes off the center of the stem, a la Trek’s Blendr mount, is a clean touch. However, just like the Blendr mount, the plastic construction is a far cry from a high-end metal product like a K-Edge mount.

It is also hard to tighten the nut down enough to keep bigger computers like the Edge 1030 from flopping down on rough terrain. Great idea but so-so execution. 

Most standard road seatposts are 27.2mm in diameter. Cannondale goes with a narrower 25.4mm post, which flexes more
Most standard road seatposts are 27.2mm in diameter. Cannondale goes with a narrower 25.4mm post, which flexes more
Ben Delaney / Immediate Media

For the road endurance riding position of this bike, I love the Fabric Scoop Shallow Race saddle.

Its wide tail is supportive without feeling overbearing, and the padding level hits the sweet spot. The saddle isn’t ideal for a flat-back racing position, but that’s not what this bike is designed for.

Fabric continues to impress me with its cleanly designed and, more importantly, nicely ergonomic saddles.

Bottom line: voodoo levels of smoothness in a high-value, mostly Dura-Ace package

Like many big brands, Cannondale offers bike models at various levels, The Synapse Carbon sits below the Synapse Hi-Mod, using slightly cheaper carbon. But by no means is the frameset a budget proposition — the Synapse Carbon sings on rough roads.

By using modest wheels and a few substitute parts, Cannondale delivers a silky smooth frameset with a premium Dura-Ace hydraulic braking groupset. Even the saddle feels deluxe. 

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If you’re interested in this bike, I’d suggest this test — have the shop set the air pressure without you looking, then ride it and try to guess. My money says you’ll be amazed at the answer. 

During the first few rides, I pulled over to check my air pressure, convinced my tires were going flat because the ride was so soft
During the first few rides, I pulled over to check my air pressure, convinced my tires were going flat because the ride was so soft
Ben Delaney / Immediate Media

Product Specifications

Product

Name Synapse Carbon Disc Dura-Ace
Brand Cannondale

Bottom Bracket FSA BB30
Brake Levers Shimano Dura-Ace 9120
Seatpost Cannondale SAVE Carbon, 25.4mm
Shifters Shimano Dura-Ace 9120
Stem Cannondale C1 Ultralight, 2014 Alloy, 31.8, 6 deg. w/ integrated Garmin Mount
Weight (kg) 7.8
Year 2018
Weight (lb) 17.2
Chainstays (cm) 41
Saddle Fabric Scoop Shallow Race, Ti Rail
Top Tube (cm) 56.1
Wheelbase (cm) 99.5
Head Tube (cm) 17.3
Stack (cm) 59
Reach (cm) 38.6
All measurements for frame size tested 56cm
Seat Angle 73.5
Rims Fulcrum Racing 500 DB, Alloy Clincher, 17mm inner, 26mm deep
Brakes Shimano Dura-Ace 9170 hydro disc, flat mount, 160/140mm
Front Tyre Vittoria Rubino Pro 700x28c
Cassette Shimano Ultegra R8000, 11-30t
Chain Shimano HG701
Cranks Cannondale HollowGram Si, BB30a, w/ OPI SpideRing, 50/34
Fork Synapse Disc Asymmetric, SAVE PLUS
Front Derailleur Shimano Dura-Ace 9100
Front Hub Fulcrum Racing 500 Disc, 100x12mm
Front Tyre Size 700x28C
Rear Tyre Size 700x28C
Grips/Tape Cannondale Grip Bar Tape w/Gel, 3.5mm
Handlebar Cannondale C1 Ultralight, 7050 Alloy, Compact
Head Angle 73
Headset Type Synapse Si, 25mm carbon top cap
Rear Derailleur Shimano Dura-Ace 9100
Rear Hub Fulcrum Racing 500 Disc, 142x12mm
Rear Tyre Vittoria Rubino Pro 700x28c
Bottom-bracket drop (cm) 7.3