Cannondale Synapse Carbon 105 SE review

A toughened up Synapse for the more adventurous rider

Our rating 
4.0 out of 5 star rating 4.0
GBP £2,299
$2,850
Cannondale Synapse Carbon 105 SE

Our review

A wonderful all-rounder that errs towards all-road duties
Pros: Blissfully smooth with well-balanced handling
Cons: The weighty wheel and tyre combo dulls some of the road excitement
Cannondale’s Synapse has a big reputation round these parts, and the previous generation won our coveted bike of the year award back in 2014 (in fact, I bought that very bike and still own and ride it frequently).

What makes the Synapse such a great bike is just how sorted Cannondale has got its endurance geometry, the 610mm stack and 393mm reach with a wheelbase 9mm over a metre is balanced with a 58mm trail figure on the forks and a bottom bracket drop of 70mm (reduced, to account for the use of larger tyres especially prevalent on this 30c equipped edition).

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The frame weighs in at 1,100g, and the fork 367g, which is decent for an endurance bike (in fact it’s significantly lighter than the previous generations premium Hi-Mod chassis) and it’s a design that’s evolved from the original.

We love the way in which the oversized chainstays twist and flatten to meet at minimal thru-axle compatible rear dropouts. These then meet with pencil-thin seatstays leading up to the super slender 25.4mm seatpost for rear-end compliance — even though on this SE version the slender post is alloy rather than carbon you can still feel the seat tube flex.

It’s practical too, with generous tyre clearance and a full set of hidden guard mounts and a removable fender bridge on the rear seatstays.

The Synapse is the sort of bike that simply revels in tight technical turns while at the same time feels sublimely balanced when carving through fast open bends and long descents.

It’s a rare thing for a bike aimed at ‘endurance’ events to be quite so sharp to turn, and so reactive and nimble with it. Or at least it would from previous experiences on board plenty of variants of the Synapse.

Cannondale si chainset
Cannondale’s own lightweight Si chainset matched with the full new Shimano 105 group performs sublimely well
David Caudery/Immediate Media

This SE version has a lot of pluses: the full new Shimano 105 group matched to Cannondale’s own lightweight Si chainset performs sublimely well, the chassis and big volume tyres make road vibrations a thing of the past and Fabric’s Scoop saddle is already a classic in comfortable performance saddles.

It’s just that in Cannondale’s pursuit to make the SE all things to all people, and make the most of its generous tyre clearances, the addition of the WTB/Formula wheelset combined with big tyres dulls the nimble edge of the Synapse when it comes to rapid progress on the road.

The rims are fashionably wide (24mm external, 19mm internal) and they build into a strong wheel that doesn’t flex but feels sprung enough to not ride hard. It’s just not a light wheelset, coming in at around 1,900g, and add in big tyres and the extra weight of inner tubes (though tyres and rims are tubeless ready) and it hampers the normally flighty Synapse on gradients above around 7 percent.

I think a transition to full tubeless would liven things up a bit, but if you’re more road than all-road I’d recommend looking at a more road-biased Synapse (such as the £100 cheaper Carbon 105). You’ll still make it up any climb, the wide gearing 50/34 with an 11-34 means that lightest 34-34 pretty much ensures it.

Though if you do want to spread your horizons a little the SE’s 30c Exposure tyres are a welcome companion. I switched in a few deviations from our standard test routes on the Synapse and took to some un-metalled roads and suddenly the SE started to make sense. The compliant frame and capable rubber means you can make some serious progress over surfaces that would stop other endurance bikes in their tracks — or at least leave you mending punctures.

Overall, the SE left me a little confused; on the road it hasn’t the same zing we’ve come to love from the Synapse, yet off road its zing comes back. It’s just, if I wanted a bike that’s great in the grit and okay on the road I’d probably opt for Cannondale’s new Topstone, or its unique Slate.

Yes, you are getting one of the best endurance chassis around with the SE, but ideally I’d add a second set of lighter wheels and slimmer tyres for the days when you want to stay on the blacktop.

Cannondale synapse carbon 105 SE specifications

  • Sizes (*tested): 48, 51, 54, 56, 58*, 61cm
  • Weight: 9.52kg
  • Frame: BallisTec carbon
  • Fork: BallisTec carbon
  • Chainset: Cannondale Si
  • Bottom bracket: Cannondale alloy Press Fit 30
  • Cassette: Shimano 105 11-34
  • Derailleurs: Shimano 105
  • Shifters: Shimano 105
  • Wheelset: WTB STP i19 TCS rims on Formula RX-512 hubs
  • Tyres: WTB Exposure TCS
  • Wheel weight: WTB Exposure TCS
  • Stem: Cannondale C3 6061 alloy
  • Bar: Cannondale C3 6061 alloy
  • Headset: Synapse Si
  • Saddle: Fabric Scoop Radius Sport
  • Seatpost: Cannondale C3, 6061 alloy
  • Brakes: Shimano 105 7070 hydraulic disc, 160mm rotors

Cannondale synapse carbon 105 SE geometry

  • Seat angle: 72.5 degrees
  • Head angle: 73 degrees
  • Chainstay: 41cm
  • Seat tube: 55cm
  • Top tube: 58cm
  • Head tube: 19.7cm
  • Fork offset: 4.25cm
  • Trail: 6.1cm
  • Bottom bracket drop: 7cm
  • Bottom bracket height: 27.5cm
  • Wheelbase: 1,010mm
  • Stack: 61cm
  • Reach: 39.3cm
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BikeRadar would like to thank Stolen Goat, Lazer, Northwave and Effetto Mariposa for their help and support during our Bike of the Year test.