Cannondale Synapse Carbon 1 RLE review


The Cannondale Synapse Carbon 1 RLE tops a revamped range of the venerable endurance bike.

Cannondale has positioned the Synapse further away from racing and more towards the everyday rider with wider tyre clearances, a focus on design simplicity and the inclusion of a battery powered lights and radar system dubbed SmartSense.

Functionally the revised bike is excellent, offering confident handling characteristics and plenty of comfort.

The Synapse Carbon 1 RLE is undoubtedly expensive at £9,000, but its excellent spec supports a nicely considered frameset design that marks it out among similarly priced competitors.

The SmartSense system may appeal and stand to benefit riders, but due to a few performance quirks not everyone will welcome it.

Despite the system, it is refreshing to see Cannondale attempt to refresh the flagging endurance bike category and, fundamentally, the latest Synapse is the best iteration of the model to date.

Cannondale Synapse Carbon 1 RLE: Development

The Cannondale Synapse was introduced very close to the inception of the endurance bike genre and continues to be one of the best examples of the breed.

The category faces an increasingly tough sell though. Race bikes with larger tyre clearances now have ever more concessions to comfort and are taking market share on one side of the endurance bike space, with lightweight gravel bikes encroaching on the other side.

Endurance road is in danger of becoming obsolete thanks to the expanding capabilities of other designs. The category needs to bring something new to the table in order to stay relevant, which is exactly what Cannondale has aimed to do in its latest revision of the Synapse.

The new Synapse has more tyre clearance, and Cannondale says the bike is more comfortable and a little bit faster too, thanks to the adoption of a few design cues from the brand’s SystemSix aero race bike.

Yet the headline update is the inclusion of Cannondale’s new ‘SmartSense’ system, a combination of safety features powered by a down tube-mounted battery.

Synapses of old have always offered the scope to be raced (and have been successfully at the highest level: Peter Sagan won Gent-Wevelgem and came sixth at Paris-Roubaix aboard one), but now Cannondale has repositioned the bike more firmly towards the needs of an everyday rider.

Those needs – that centre around versatility, reliability and ease of use – are evident in the frameset updates.

Cannondale Synapse Carbon 1 RLE: Frameset and build

Despite a strong trend to the contrary elsewhere in the market, the Synapse’s cables remain external from the bars to frame. This sidesteps the issues of tricky routing paths and the quirky headset arrangements necessary to accommodate fully internal cables.

The Synapse has reverted back to a BSA threaded bottom bracket too, eschewing Cannondale’s own BB30 standard which the brand has used since 2000.

‘We wanted to use the simplest one that requires basically no maintenance,’ says David Devine, Cannondale’s senior product director.

There are mounts aplenty and tyre clearance has been bumped up to 35mm. It affords the Synapse the scope to fit pseudo-gravel tyres, and potentially moves the bike into that rather nebulous ‘all-road’ category that sits somewhere between endurance and gravel.

The seatpost goes back to being secured with a conventional collar as opposed to a wedge and even the dropouts have been made more user-friendly, switching from Mavic’s increasingly esoteric speed-release standard to regular thru-axles.

The parts bolted onto this altogether more sensible frameset are just well-rationalised.

Shimano’s Dura-Ace R9200 groupset is unsurprisingly brilliant, with front shifting noticably improved over the last generation’s already consummate performance. With the smooth switch between chainrings and the close gear steps of the 12-speed cassette, gear transmission on the Synapse is an effortless experience.

Cannondale’s HollowGram Save seatpost is now a conventional 27.2mm diameter rather than a proprietary 25.4mm, and despite looking sleek the cockpit remains a two-piece, adjustable combination of Cannondale’s HollowGram Save alloy stem and carbon bars.

The Synapse Carbon 1 RLE rolls on Cannondale’s HollowGram Knot SL 45 wheels and Vittoria’s superb 30mm Corsa tan wall tyres.

All told the bike’s spec is bulletproof in both premise and performance, but then again for £9,000, so it should be.

That just leaves the SmartSense system. It comprises a down tube-mounted battery that powers a combination of front and rear lights and radars designed in partnership with Lezyne and Garmin.

A front-hub mounted sensor activates them all when the wheel starts to roll and communicates with all common head units as well as a Cannondale app, which acts a control centre to fine-tune preferences and display the health of the system.

Cannondale Synapse Carbon 1 RLE: Geometry and sizing

In contrast to the rest of the bike, on the geometry side of things there are very few changes to report. The back end has been made 5mm longer but the head angle has been made a little steeper, potentially as an antidote, and the bike’s high stack and short reach figures are essentially unchanged.

The new model has also been treated to Cannondale’s ‘Proportional Response size-specific design’. The brand says this means each of the Synapse’s six sizes receive specific geometry and stiffness characteristics based in the expected rider size, so in theory the size 56cm Synapse I – at 185cm (6ft 1in) and 84kg – have reviewed should ride the same as the 48cm size under an appropriately shorter, lighter rider.

There’s the argument that this should be done as a matter of course anyway, and there isn’t any way anyone can confidently quantify this as being achieved, but it is nice nonetheless that Cannondale says it has considered it properly.

Riding the Cannondale Synapse Carbon 1 RLE

Such little change geometrically means that the new bike behaves similarly to the Synapses before it on the road, which is wholly a good thing.

The ride position is easy to sustain, it tips into corners willingly but feels beautifully secure when in them and I can’t remember riding anything recently that has been so comfortable.

Cannondale speaks about the dropped seat stays and revised carbon frame layup helping the new bike boast an 8% increase in flex, but I’d wager much of the comfort is created by the brand’s brilliant HollowGram Save seatpost and bars.

No doubt the 30mm Vittoria tyres only help their cause too, but both components have been shaped to promote vertical flex. Consequently, the way they mute vibration is uncommonly effective.

I haven’t previously thought of Cannondale as offering components of a similar quality to the in-house brands of bike makers like Specialized (Roval) and Trek (Bontrager), but the Synapse’s finishing kit is every bit as good.

Consequently, the components support the frame excellently and amount to a bike that is a delight to ride.

Cannondale Synapse Carbon 1 RLE: Using SmartSense

If fundamentally the new Synapse is better than ever, I don’t think its bells and whistles are as successful an update though.

The Cannondale app provides a wealth of data about the bike via SmartSense that many inexperienced users will likely find useful and/or interesting, such as predicted component service intervals (although actual service intervals will be entirely dependent on individual maintenance routines).

The system was easy to set up, intuitive to adjust and repeatably hassle-free to connect to.

In use however, I struggled to fully get on board with the devices SmartSense powers. Having had little experience with Garmin’s Varia radar before meant that being artificially made aware of approaching vehicles before I would otherwise naturally recognise them was disconcerting rather than reassuring.

Call me old fashioned, but I prefer to rely on my senses than gadgets to ensure my safety in most instances. On the other hand, perhaps I just needed longer with the system to familiarise myself with it. I know that many others have reported positive experiences using it.

What’s more, given that their primary function will be to let the rider be seen rather than see, I think the lights are too bulky, and my issues don’t stop there.

The rear light/radar device blocks the installation of a saddlebag (the separate purchase of an action camera extension bracket frees that area back up though), the system’s approximate three-hour battery life is underwhelming (although SmartSense systems sold in the UK will not have to adhere to European st-ZVO regulations, meaning run-time will extend to a claimed 10 hours).

The battery could have been more neatly integrated too. Down tube hatches are not a new concept and I’d say one could have been successfully employed here to house the battery more smartly as well as protect it better. However I do admit that I’m no engineer, and perhaps such integration added too much complexity to make it worthwhile on balance.

The SmartSense system is claimed to weight just shy of 500g, and I couldn’t help feeling that the extra half a kilo neutered the bike uphill somewhat too, toning down a ride feel that has always before felt pleasantly lively.

Cannondale Synapse Carbon 1 RLE: Final conclusions

It’s not that I don’t see Smartsense’s merit – I think an appreciable sector of the market the Synapse is now aimed at will welcome its inclusion – I just feel that for a rider like me (who I’d like to believe represents a large proportion of keen, but thoroughly normal, cyclists) the disadvantages of it outweigh its potential benefits.

By including versions of the SmartSense system on all specs but the entry level Synapse, the bike feels like it now caters for an audience that likes riding but doesn’t necessarily feel the same passion for the bike they ride.

They just want a machine equipped to such a comprehensive extent that it doesn’t have to be considered in a way that many other cyclists obsess over.

It’s a shame, because the Synapse’s shifted market position may preclude a lot of riders whose enjoyment of cycling would otherwise stand to be improved by choosing a Synapse. As a stripped-down, conventional bike, the thing is that good.

I would urge Cannondale to reconsider the application of the SmartSense system. To lighten it, to more seamlessly integrate it, and maybe to not include it as standard on all models but offer equivalents without, or make it available as an extra at the point of purchase, for example (if all else fails, I’m told it is easy to strip out of the bike). 

That remains something to hope for in the next Synapse perhaps. In the meantime, and despite my feelings about the SmartSense system, I would still applaud Cannondale for its widely sucessful attempt to refresh an important but flagging bike category – designs like the Synapse show that there is still life in the old dog yet.

Pick of the Kit

100% Eastcraft sunglasses, £169.99

100%’s new Eastcraft sunglasses sport an aviator like silhouette but their squared-off shape marks them out as a competitor to Oakley’s Sutro design. After using them in the recent piercing spring sunlight I’d say they can hold their own. The optics of the 100% lens are top-notch and they offer an impressive field of view.

They do come with side ‘shields’ which 100% says offers protection against the elements, but thankfully they are detachable as the only thing I found they protected me from was my peripheral vision. With them removed I think the glasses just about work casually too.

Cannondale Synapse Carbon 1 RLE alternatives

Cannondale Synapse Carbon LTD RLE

The £6,750 Carbon LTD RLE is the Synapse range standout for me. It uses the same excellent finishing kit and still has electronic gearing, but the change to Shimano’s GRX groupset knocks over two grand off the price.

Cannondale Synapse Carbon 4

The £2,400 Synapse Carbon 4 model is the only choice without some combination of the SmartSense system as standard. Given my reservations about it and this model’s solid frameset, it’s an attractive option to buy and upgrade as you go.


Price £9,000
Brand Cannondale
Frame Synapse Carbon
Fork Synapse Carbon
Weight 8.2kg (56cm)
Sizes available 48cm, 51cm, 54cm, 56cm, 58cm, 61cm
Levers  Shimano Dura-Ace R9270
Brakes Shimano Dura-Ace R9270
Front derailleur Shimano Dura-Ace R9250
Rear derailleur Shimano Dura-Ace R9250
Chainset Shimano Dura-Ace R9200
Bottom bracket Shimano Dura-Ace R9100
Cassette Shimano Dura-Ace R9200
Chain Shimano Dura-Ace R9200
Wheels Cannondale HollowGram Knot SL 45
Tyres Vittoria Corsa, 30mm
Bars Cannondale HollowGram Save Carbon
Stem Cannondale HollowGram Save alloy
Seatpost Cannondale HollowGram Save Carbon
Saddle Fizik Tempo Argo R3

Main photo: Lizzie Crabb; Synapse Carbon LTD RLE & Synapse Carbon 4 photos, geometry chart and SmartSense screens: Cannondale

Products reviewed by Cyclist are independently selected and tested by our editorial team. Cyclist may earn an affiliate commission if you make a purchase through a retailer link. Read our reviews policy.

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