The Genesis Datum joins a class occupied by the brilliant Cannondale Synapse and Giant Defy, but while both those bikes limit tyre size to 28mm – and lack mudguard eyelets – the Datum accommodates 33mm tyres and has mounts for full-length mudguards. Add a beautifully finished carbon fibre frame and fork, a slick shifting Shimano Ultegra Di2 drivetrain with hydraulic disc brakes, wonderful Challenge Strada Bianca tyres, and you have a hugely capable bike that is loads of fun over all sorts of terrain.
The Datum isn't available in the shops yet, but you can order it. Here's our exclusive first review, ahead of it arriving at a bike shop near you.
How does it ride?
Genesis has worked wonders with the geometry, and the result is a bike that has a very sure-footed approach, whether cruising along a smooth road or exploring gravel paths and singletrack.
If you don’t race and you like a slightly taller front end, you’ll be right at home on the Datum. Long rides are dispatched with ease. I was impressed with how comfortable it was during a 190km ride, during which the Datum revealed a quick turn of pace, with lively handling that makes it a fun bike to ride.
There’s never a dull moment on the Datum. There are few direct rivals but it most reminded me of the Giant Defy Advanced, a long-legged distance bike that also manages to have a playful personality.
It’s not a race bike, but the Datum is no slouch. The 30mm tyres fitted to this test bike display a slight hesitation in acceleration from low speeds, but it’s minimal really and once up to a decent speed they roll along with impressive ease. Any concerns that they would be draggy and slow compared with a narrower tyre soon faded as the miles racked up, and the more I rode them, the more I was won over. Comfortable, smooth, loads of grip and not at all slow. Just wonderful.
The ride of the Datum is quite firm; it doesn’t exactly cosset you from the road surface, but with around 80psi in the tyres they soak up the most cracked and potholed roads sufficiently. The tyres’ high level of grip also increases confidence on badly surfaced roads in poor conditions, with none of that skittish behaviour typical of a race bike on skinnier rubber.
With the Datum’s huge frame and fork clearance around the tyres – and space for proper full-length mudguards, a bonus for winter riding – you can really entertain any desire to head away from congested roads and onto gravel paths, bridleways and woodland singletrack, with little fear of clogging or sharp objects being squeezed between tyre and frame.
Having said that, even though the Challenge tyres are capable of withstanding some rough riding, if I was going to be spending more time exploring off-road trails I’d prefer a tubeless setup.
But it’s on the road that the Datum really excites and entertains. Despite the tall front end and big tyres it’s still a sporty bike and indulges any desire to ride at speed. The steering is quite light and direct, and the hydraulic disc brakes give you a level of control that conventional brakes can’t match, especially in the wet.
The stiff front end provides sharp cornering accuracy, and the steering feel and easily accessible drops (because of the longer fork) make it a natural in the turns. Add in the huge traction from the tyres and this is a bike that’s very much at home on the descents, especially on poorly surfaced and wet roads where it is outstanding. It climbs well too, considering its weight, which at 8.91kg really isn’t that bad for this sort of bike.
The Datum is simply a really nice riding carbon fibre road bike in the endurance/sportive mould, and it just happens to take bigger tyres than just about any other bike in its class. It can handle anything you throw at it (I even fitted some cyclo-cross tyres) and delivers plenty of performance.
Few bikes deliver such a complete package as the Datum: it’s fast and fun enough for summer riding and ready for the winter with mudguards and disc brakes.
The frame: Carbon fibre, thru-axle fork and mudguard mounts
The Datum, from a company once best known for producing steel, aluminium and titanium frames well suited to UK riding conditions and styles, is Genesis’s second carbon fibre offering, following hot on the heels of the Zero race bike, developed for the Madison-Genesis race team. It might upset a few traditional Genesis fans, but the use of carbon fibre has provided the freedom necessary to create the Datum.
Road bikes have been evolving quite rapidly in a few short years. Models like the aforementioned Synapse and Defy have proved popular with British cyclists seeking a bit more comfort from wider tyres and a frame geometry that is a little less aggressive than an out-and-out race bike.
The recent gravel and adventure bike trend has also been raising eyebrows and increasing the appetite for even wider tyres and bikes with the ability to head into the wilderness – you only need look at the growing popularity of events like the TransContinental to see how people’s attitudes to riding and bikes is changing.
Possibly because of all this, it’s easy to get hung up on trying to categorise bikes. The Datum, though, is simply a carbon fibre road with disc brakes and big tyres. It’s at home on the road, with long distance comfort aplenty. It’ll tackle gravel paths, bridleways and even singletrack if you’re that way inclined.
It’s built along similar lines to the Synapse and Defy. They’re both popular bikes, but I know that many dislike the lack of mudguard mounts, and that for some, a 28mm tyre just isn’t wide enough anymore. The Datum, with its massively increased tyre capacity and ability to fit proper, full-length mudguards front and rear, is, in a way, the natural evolution of those endurance and sportive bikes, with no drawbacks or compromises.
Its carbon fibre frame is bristling with modern details. There’s a BB86 press-fit bottom bracket, tapered head tube, and fully internal gear and brake routing, with the rear brake hose passing through the down tube. The top tube slopes dramatically, providing good standover clearance, and meets a 27.2mm-diameter seatpost. A detail that will satisfy any adventure or bikepacking cyclists is the addition of a third bottle cage mount on the down tube.
To provide the necessary tyre clearance in the rear of the frame, Genesis has curved the seat tube around the rear wheel. It’s the sort of thing you typically see on a race bike shaped in a wind tunnel, but there’s no aero consideration here, it’s purely a smart way of keeping the chainstays short (420mm) while still providing space for the big tyres. The curved seat tube should provide a smidgen more deflection as well, reckons Genesis.
Up front Genesis uses a carbon fibre fork with a 15mm bolt-thru axle (the axle fits through holes in the fork dropouts rather than slotting in). Its 397mm axle-to-crown measurement is typical of what you’d get on a cyclo-cross bike, and is necessary to provide the tyre clearance.
To offset its length, the head tube is short, just 155mm on the 56cm (medium) model tested. The crown has a squared off shape to maximise space between the tyre and fork, especially when a mudguard is fitted. The hydraulic hose is routed inside the fork, and there are flat mounts – replicated on the frame with a chainstay disc mount.
The geometry shapes up with a 72-degree head angle that, along with a 50mm offset fork, produces 59mm of trail, which Genesis reckons provides agility without sacrificing stability and maintains a healthy toe-clearance.
Other measurements for our medium frame are: a 561mm top tube, 1,017mm wheelbase, and 385mm reach and 585mm stack (the horizontal and vertical measurements from the centre of the bottom bracket to the top of the head tube).
Build: Electronic shifting and hydraulic disc brakes
Genesis is offering the Datum in three builds: the Datum 10 (£1,799) equipped with Shimano Tiagra and TRP HyRd disc brakes; the Datum 20 (£2,099), which steps up to Shimano 105; and the range-topping Datum 30 (£3,199) tested here, which packs a Shimano Ultegra Di2 groupset.
It goes without saying that the Ultegra Di2 groupset shifts perfectly, with whisper-quiet gear changes at the lightest touch of a button. It’s very easy to use. The brake levers operate Shimano hydraulic brakes, providing bountiful power with all the modulation you need to really make the most of the available stopping power. I didn’t lock a tyre once during testing, in the dry or rain, and experienced no brake rub or untoward noise.
The brakes are Shimano’s latest RS805 Flat Mount model, paired with 160mm rotors front and rear. The delivery of power and lever feel is identical to the previously tested Shimano BR-R785 hydraulic brakes, but the new callipers provide a much cleaner appearance on the fork and chainstay. The brake pads have cooling heatsink fins to help dissipate heat during prolonged use.
A compact 50/34 chainset is paired with an 11-32 cassette, which ensures you’re able to scale any climb, and is a boon if you’ve decided to load the bike with some bikepacking bags or kit for a multi-day adventure.
The Datum rolls on new Fulcrum Racing Sport DB CX wheels, and production bikes will ship with 33mm Strada Bianca tyres – the test bike was fitted with a 30mm version of the top-tier tyre with a higher (read more expensive) TPI.
The rest of the kit is Genesis own-brand stuff: aluminium handlebar (a new Randox flared drop model on production bikes), aluminium stem, seatpost and saddle. It’s all satisfactory componentry, adequate rather than exciting. I’d look at replacing the aluminium seatpost with a carbon fibre post to get a bit more rear end comfort.
How does it compare against its rivals?
For a bike with similar tyre clearance and mudguard compatibility, you have to look away from the endurance and sportive category (where 28mm tyres are commonly the widest choice) and instead investigate the growing gravel and adventure class.
The most prominent rival is the GT Grade, a bike available in carbon or aluminium with similar tyre (it’ll take 35mm tyres) and mudguard compatibility.
But another interesting choice occupying similar territory is the excellent Jamis Renegade. Its carbon frame is equipped with disc brakes and space for up to 40mm tyres, along with a full complement of rack and mudguard mounts. It also has a 15mm thru-axle fork. And it’s a bit of bargain, with prices from £1,400 up to £2,500.
A new option, which we’ve only had a first ride on so far, is the Felt V Series. Like the GT Grade it comes in aluminium or carbon fibre and the frame will accept up to 40mm tyres – it ships with either 28 or 32mm tyres – and there are also rack and mudguard eyelets for that year-round versatility.
If you want a bike to do it all, then you should take a serious look at the Genesis Datum, a prime contender for bike of the year
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road.cc test report
Make and model: Genesis Datum 30
Size tested: 56
About the bike
State the frame and fork material and method of construction. List the components used to build up the bike.
The Datum is an all-new model for 2016 and one that fits right in with the ethos of Genesis as a brand. Datum is a disc-braked carbon road bike range, with large (nay, huge!) tyre clearances. Don't necessarily think of Datum as a gravel bike, more a comfy, fast road bike with a more versatile twist.
Tell us what the bike is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about the bike?
Frame : 24/30T Monocoque Carbon Road Disc w/ Tapered Headtube & Fully Internal Cable Routing
Fork : Full Carbon Fork w/ 1-1/2' – 1-1/8' Tapered Steerer & Ø15mm Thru-Axle
Headset : FSA Orbit C-40 / No.42 Integrated
Shifters : Shimano ST-RS785 Di2
Rear derailleur : Shimano Ultegra Di2 RD-6780-GS
Front derailleur : Shimano Ultegra Di2 FD-6870
Chainset : Shimano Ultegra FC-6800, 50/34T
Bottom Bracket : Shimano BB-RS500, Press-fit 86.5mm
Chain : KMC X11
Cassette / Freewheel : Shimano CS-5800, 11-32T, 11sp
Wheelset : Fulcrum Racing Sport DB CX
Tyres : Challenge Strada Bianca, 700–33c, 60TPI, Folding
Brakes : Shimano BR-RS805 w/ SM-RT86 160mm Icetech Rotors
Brake Levers : w/ Shimano ST-RS785 Di2
Handlebars : Genesis RandoX Flared (D125 x R70mm)
Grips / Tape : Genesis PU Shockproof Anti-Slip
Stem : Genesis Road, +/-7°
Saddle : Genesis Road
Seatpost : Genesis Road, Ø27.2 – 350mm
Frame and fork
Tell us about the build quality and finish of the frame and fork?
Excellent build quality and attention to detail.
Tell us about the materials used in the frame and fork?
Full carbon fibre construction with a tapered head tube and bolt-thru axle fork, with internal cable routing.
Tell us about the geometry of the frame and fork?
Loosely based on the popular Equilibrium, the new Datum has a higher front end and sloping top tube.
How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?
Almost spot on - I just changed the stem for a longer one.
Riding the bike
Was the bike comfortable to ride? Tell us how you felt about the ride quality.
The big volume tyres provide a big boost in comfort over narrower tyres.
Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?
A very stiff front end gives the bike a very direct and communicative feel.
How did the bike transfer power? Did it feel efficient?
No flex from the frame when you push hard on the pedals.
Was there any toe-clip overlap with the front wheel? If so, was it a problem?
How would you describe the steering? Was it lively, neutral or unresponsive? Light and lively.
Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?
Despite the tall front end and big tyres, it's still a sporty bike and indulges any desire to ride at speed.
Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?
The electronic shifters are a joy to use and the hydraulic disc brakes provide a braking performance that is far improved over conventional calliper rim brakes.
Which components had the most effect (good or bad) on the bike's stiffness? would you recommend any changes?
I'd look to change the seatpost for a carbon fibre one to provide a bit more deflection/comfort at the rear.
Which components had the most effect (good or bad) on the bike's efficiency? would you recommend any changes?
The big volume tyres are impressively smooth and comfortable and not at all slow.
Wheels and tyres
Did you enjoy riding the bike? Yes
Would you consider buying the bike? Yes
Would you recommend the bike to a friend? Yes
Use this box to explain your score
The Datum just does everything so well. It's fast and fun enough for a summer distance bike, the disc brakes and full mudguard mounts will make it an ideal winter bike choice, and you could even fit cyclo-cross tyres for more adventurous riding.
About the tester
Age: 31 Height: 180 Weight: 67kg
I usually ride: My best bike is:
I've been riding for: 10-20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, touring, mountain biking
David has worked on the road.cc tech team since July 2012. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds.