Cannondale Synapse Carbon 2 review: Dependable and sure footed, but not as exciting to ride as some of the best endurance bikes on the market

The Cannondale Synapse has been around for a long time now, over twenty years in fact, and in that timespan it's been through various iterations as road bikes have developed.

The Synapse sits in Cannondale's Endurance road section, and when this sixth-generation model launched in May last year, the brand said, 'unless you are a WorldTour pro, the Synapse is the perfect road bike for any job.'

I'm not a WorldTour pro, and I have spent around five months riding this bike exclusively on the road, to really see if this is everything I might need in a performance road bike.

The Synapse, for the uninitiated, is Cannondale's more comfortable, more upright, yet still sporty endurance road bike. I've been testing the Carbon 2 model, which sits about in the middle of the range, though it isn't particularly cheap. If you're looking for comfort but still want a performance-oriented road bike, then the Synapse could be a bike to consider, and this review will get into the details of how Cannondale's endurance machine performs.

The Synapse and I didn't get off to a great start, which I talk about more below, but I've ridden it for several months, through the winter and am heading into spring on this bike. Regardless of anything else, we've certainly formed a bond after all the miles we've spent together.

Design and aesthetics

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The Synapse blends performance and more endurance-specific design elements into an overall frame shape that's pretty easy on the eye.

The bike has received aerodynamic attention from Cannondale, evidenced by things like the blind front fork dropout, D-shaped seatpost, and sculpted headtube, but then the gravel bike tyre clearances and kinked seat tube move things out of race bike territory.

The previous generation Synapse arrived with an integrated SmartSense lighting system, which got cleaned up last year for the sixth-gen bike. There are three SmartSense bikes in the Synapse range, which provide integrated lights, radar, and a battery. The other five models are standard non SmartSense bikes, and the Carbon 2 model here is the second priciest 'standard' model at $6,499 / €5,899 / £5,995. If you really like the idea of not having to ever worry about taking lights on and off your bike, the starting point for a SmartSense model is the Carbon 3 SmartSense bike at £4,995 / $4,999.

Some aspects of the bike, like the fork, downtube and headtube, as mentioned, share similarities with the SuperSix, but the huge tyre clearances Cannondale has given the Synapse highlight that this is a machine built for a different purpose. You can fit a 42mm tyre in the rear and a 48mm tyre up front, and that's with 4mm of clearance on either side. That's still more than plenty of dedicated gravel bikes.

Clearly, there is room to fit gravel tyres and mix things up. I've gone nowhere near that big for my test bike, but it highlights what you could do with a Synapse, depending on what groupset and, crucially, gearing it has.

Other endurance-related design features include the new StashPort downtube storage hatch and bag which are handy for storing spares, mudguard mounts, and the ability to fit a top tube bag should you wish.

The Carbon 2 model comes in the grey colour you see in the photos; it's a sort of satin finish with some gloss black sections in places, and I think it looks good. Perhaps slightly plain for some, but it's an unfussy paint scheme that overall works well.

In terms of details, this bike is UDH hanger-friendly and has a BSA 68 threaded bottom bracket, which should be hassle-free; indeed, the days of Cannondale pressfit road bottom brackets seem to be retreating further into the distance now with every passing year. The bike also features fully internal cabling, and the fork makes use of Cannondale's V-shaped Delta fork steerer to facilitate this.

This is a bike that focuses on comfort, and the geometry sheet for the Synapse stayed very similar to the previous generation bike. Some changes were made, in part to accommodate the bigger tyres. The bike got longer, as did the chainstays, in part to boost the tyre clearance, but the stack and reach numbers stayed almost the same. We'll come back to this because I think the Synapse geo is key to whether it works for you as a platform.

The Carbon 2 comes with a solid enough spec, including a Shimano Ultegra Di2 groupset, DT Swiss ERC LOG 45 wheels, Vittoria tyres and Fizik finishing kit.

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Performance

I'll kick the performance section off with the Synapse's geometry. I didn't have a pleasant first ride or two on the Synapse; I really felt uncomfortable on the bike, and didn't click immediately with it at all. Sometimes you set your position on a test bike, set off, and things are right instantly. The recently launched Cannondale Supersix Evo was one such bike, and the 54cm SuperSix I rode felt far better for me than a 54 Synapse.

On my maiden ride I felt too slack and stretched out, and not one with the bike at all. The position felt quite old school, and I had to spend some time altering handlebar roll, saddle setback posistion and shifter angle to get comfortable. I have been able to find a comfortable position on the bike since, and there's also been an element of me adapting to the bike.

This bike's stack and reach numbers of 570 and 381mm, paired with a 100mm stem, work fine for me on paper, but in reality, things felt off. Working out why has been my biggest challenge regarding the Synapse.

I'm comfortable on the bike now after months of riding, but it's not a joy. I don't feel like I'm sitting in it, more on top of it. To break this down, I generally feel too far behind the bottom bracket, a touch too stretched when riding normally. When riding with intent, things are fine, and the taller front end has made it easy to hold an aero position, but it does feel on the high side for me overall with this position. I've ridden the bike slammed for the most part, and part of the charm of the Synapse is that you should be able to dispense with lots of spacers thanks to the taller front end.

I attribute a lot of this feeling to the seatpost and handlebars. The post has a 15mm offset, as do all 51-61-sized models, and the 42cm alloy Vision Trimax aero alloy bar, which comes on a few Synapse models, has a 7-degree forward angle, i.e the bar slopes forward from the stem clamp, which increases the reach of the bar

For context, the stock reach number of the handlebar is 90mm, which is 10mm more than the new Cannondale SystemBar found on the new SuperSix Evo race bike. I don't need a huge amount of reach on bikes generally, and wonder if Cannondale specified this bar to try to counteract the shorter reach for some riders. It feels like an odd choice, and for this kind of bike, shorter is nearly always better in my opinion when it comes to comfort.

The Synapse stack and reach numbers are in line with other endurance or all-around bikes; it's 2mm taller and 6mm longer than a small Canyon Endurace, and 7mm taller and 2mm longer than a Ridley Grifn RS. It also has about the same reach number as both the Specialized Roubaix SL8 and Pinaello Dogma X, all endurance / all road bikes I have tested and felt a lot more comfortable on and at one with.

The bike got longer, and gained longer seatstays, but the ride doesn't feel particularly snappy or exciting, nowhere near as exciting to ride as Canyon Endurace. That bike has a half-degree steeper seat tube angle and a shorter wheelbase.

The Synapse's 73-degree seat tube and 1,026mm wheelbase make it slacker and longer than even the the Specialized Roubaix. I'd swap that offset post and fit a handlebar with a shorter reach to try and make the Synapse feel and ride how I want it to. I'll also point out that the next size down from a 54 is a 51, a jump that may leave some in between sizes. Cannondale rectified this gap and introduced a new 52 size at the launch of the latest SuperSix.

My advice for a prospective buyer regarding geometry would be to check the geo, test ride a Synapse, try a friend's, or consult a bike fitter, to see if the geo produces the kind of ride you want. The bike rides very well, which I'll talk about next, but I think Cannondale could update the fit to match other modern endurance bikes on the market whilst keeping the stability that comes from the wheelbase and some of the geo angles.

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In terms of the ride experience and overall performance, the Synapse is a strong endurance bike. The handling is confidence-inspiring, stable, and sure-footed. The bike is also a strong descender, whether it's at high speed in a straight line or making fast line changes. It's really solid, just not as fast or agile as the SuperSix, which you would expect.

The bike is comfortable; I wouldn't say it's a feather bed, but the ride overall is smooth and stable. Tyre choice will also play a huge part in this overall feel. You'll be starting on a butyl tube, and switching to something like a 35mm tubeless tyre will give things another boost. I've had no issues comfort-wise and could happily ride the bike all day.

Overall, the ride is smooth and hugely dependable. I've done steady rides, a range of training sessions and chaingangs, and the Synapse has dealt with it all with poise.

What it just lacks for me is a bit of snap, better acceleration, and a greater feeling of speed and excitement. This I found in spades with the Canyon Endurace, which nails that blend of comfort and speed. I've ridden the Synapse really hard and sprinted on it at the end of hard rides. It's very good, but it lacks that little bit of race bike feel that some of the best endurance bikes possess that really gives you a best of both worlds experience.

Equipment-wise, the Synapse Carbon 2 comes with a solid spec list, Ultegra Di2 is long tried and tested, and the groupset hasn't missed a beat for me over the entire test period.

Some components and bits of the finishing kit wouldn't be my first choice; some of these pieces, such as saddles and handlebars, are personal and easily swapped out, but I was disappointed to see some 32mm Vittoria Rubino Pro IV tube-type tyres come fitted with the bike as stock.

The Rubinos aren't bad tyres, but I'd like something more premium come on this bike as stock to boost the ride feel, considering this is a $6,000 bike. The tyres would be one of the first upgrade points for me, and the ride experience improved when I swapped in some Schwalbe Pro One tyres.

The DT Swiss ERC LOG 45 wheels are a good, solid option, but not particularly exciting, and the 22mm inner width may mean larger gravel tyres don't fit as well. I've ridden the bike with three different wheelsets in total, including the Roval Rapide CLX III'S and the ride has improved with a wheel upgrade.

Most importantly, the stock DT Swiss wheels are included in the DT Swiss stop ride notice, which was announced last year. If you have a Synapse with this wheelset, follow the recall link for the brand's advice on what to do. I haven't had any issues with the wheels and have done plenty of riding on them, but I have switched them out for some other test models for periods of time.

Maintenance and servicing

I like to include a maintenance and servicing section for reviews. You will be buying a bike to own it for years, and I like to talk about any potential foibles.

There are no nasty surprises here; the threaded bottom bracket and Shimano Hollowtec 2 crankset mean removing the cranks and bb at home is easily done for maintenance or without hassle by a shop.

As usual, minimise the headset washing and hose blasting; bearing replacements will be more expensive, though you can access them for cleaning and regreasing.

Look after the seatpost clamp and bolt, which is integrated into the frame; corrosion or seizing there won't be fun. Oh, and you will need round headset spacers on top of the stem whilst you are playing with your position if you do invest.

Overall, there aren't any especially tricky points when it comes to the Synapse, as most modern bikes, headset replacements and internal cabling will probably give you the biggest labour bills at the bike shop.

Value

At $6,499 / €5,899 / £5,995, I don't think the Synapse 2 represents incredible value. You're getting a good quality frame and a top groupset. Everything else isn't quite as strong, and some may argue that the lack of a power meter, and more premium or even tubeless compatible tyres are glaring omissions for a bike at this kind of price point.

A bike that springs to mind as a key competitor here is the Canyon Endurace. For over $1,000 less the Endurace CF SLX 8 boasts Ultegra Di2 with a 4iiii power meter and tubeless Schwalbe Pro One tyres, though Canyon's direct sale model does provide an advantage here, it must be said.

The Specialized Tarmac SL8 Expert also comes in a little cheaper with an Ultegra Di2 groupset and Roval C38 wheels, and Specialized bikes generally aren't the cheapest machines to buy new.

In an ideal world, I'd like a bit more for my money when it comes to the Carbon 2. I'd recommend looking at the Carbon 4 model, which is over $1,000 less with the excellent Shimano 105 Di2. A later upgrade to carbon wheels still may end up being cheaper than the Carbon 2 at its stock RRP.

Verdict

The Synapse is a great endurance bike, comfortable, confidence-inspiring, with a premium ride feel and tyre clearances that are bigger than some gravel bikes.

It just lacks some excitement for me, though I'm aware some component and fit changes may improve this aspect. I'm all for a comfortable bike, but I still want it to feel racey, and despite it's capableness, I can't honestly say I've felt that from the Synapse.

This particular model hasn't set my soul on fire, but the Synapse has been around for two decades for a reason. After spending so much time on this bike, I'm excited to see where Cannondale takes it next.