Cervelo S3 Disc Ultegra Di2 road bike

'Aero-lite' disc-equipped race bike which can more than hold its own against rim-brake rivals

Within the Cervelo S-range of aero bikes, if the S5 is the rip-roaring, cutting-edge, pure-aero race machine (just ask Mark Cavendish), then the S3 is its little brother, slightly throttling back on the slab-sided aero framework to provide a slightly more ‘all-round’ flavour.

Still, it’s always been an impressive looking machine, and now the Canadian brand has seen fit to festoon it with disc brakes. It’s entirely possible that this ‘aero-lite’ bike is a stepping stone before we see discs on the S5, and if this S3 Disc is anything to go by, we’re going to be impressed when the S5 comes with rotors too.

You see, instead of simply adapting the old frame to accommodate discs, Cervelo have gone to the trouble of re-conceptualising the bike – so now instead of reeling off a litany of ‘impressive’ claims of ‘only’ small losses, we can say the S3 Disc is claimed to actually be both lighter and stiffer than the rim brake bike.

That says two main things: not only is the bike a legitimate rival to the rim brake version, but it’s so good you could be considered a touch foolish to stick with the old tech. Why would you go old school when new school is so good?

The frame has received newly-tweaked tube profiles to help cut a more streamlined and stable form through the wind, featuring a truncated shape on the downtube that partially shrouds bottles, as well as a fork that’s not only wider to fit the rotors, but features a higher crown to improve airflow through the disturbed area behind the front wheel.

The rear triangle has received similar thought: now naturally wider to fit those discs, they’ve redesigned them to accept stiffer (over quick release) thru-axles, which has the overall side-effect of improved power transfer as a whole, thanks also to a fortified and further stiffened bottom bracket area. Cervelo have also paid attention to convenience and sleekness too – with thinking borrowed from the S5, the Di2 battery is hidden away in the downtube, while the hydraulic internal cable routing has been switched to the left side of the bike to minimise cross-travel of the cables inside the bike.

RCUK 100 2017 - Cervelo S3 Disc road bike

All the while, signature Cervelo tech can be spotted throughout: BBRight asymmetrical bottom bracket shaping balances out power transfer, while the new dropouts continue to be made from compression-moulded carbon to save a few grams. Even the distinctive seattube aero wheel cutout has been retained – albeit in a minimised format compared to the S5.

There’s no messing around with the spec sheet, either. The S3 Disc is available in two models – both Ultegra. This one features Di2, so makes maximum use of the capaciousness of the downtube that houses the battery, while both come fitted with Shimano’s Ultegra-level BR805 hydraulic disc brakes.

RCUK 100 2017 - Cervelo S3 Disc road bike
RCUK 100 2017 - Cervelo S3 Disc road bike

Cervelo S3 Disc Ultegra Di2

Finishing kit is also impressive – there’s an aero carbon seatpost, while the handlebar is the Canadian brand’s own AB04 aero variety. Handily, the stem is an FSA SLK standalone unit, so there’s easy servicing and tweaking available to achieve the optimum front end fit. Let it be said: integrated bar-stems might not the be all and end all of tidy cockpit setups.

Cervelo have opted for an FSA SLK semi-compact chainset instead of Shimano’s own, but a move that really adds a sense of exclusivity to the S3 is the choice of hoops. The mechanical version sits on respectable HED Ardennes Plus GP hoops, but the Di2 version we’re featuring comes shod with glorious Enve SES 3.4s.

Few things in life are perfect, though, and we question the choice of 23c Continental Grand Sport rubber on this disc bike frame that can easily accommodate now-common, smoother rolling 25c rubber – but that’s an easy upgrade that we’d make in a heartbeat. When you buy one, you should too.

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Selected for The RCUK 100 2017

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