Genesis Datum 20 review

Britain’s Genesis was one of the pioneers of disc brakes on a road bike, and delivered a ‘rufty-tufty’ road machine too with the Croix de Fer, which launched back in 2008. While that was steel the new Datum platform is all carbon. It features a front thru axle and standard rear with the frame and fork providing massive clearances for 35mm rubber with a 45mm wide mudguard.

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Genesis has built its reputation on metal bikes, but since the debut of the impressive Zero Team carbon bike, it has fully embraced the world of composites.

That’s not to say that the Datum’s design team hasn’t learnt a trick or two after years of producing disc-equipped all-road steel bikes. The Datum uses the same geometry as the Equilibrium series, with 72-degree head and 73-degree seat angles.

The Shimano Flat Mount brakes are bulky but performance is impressive

This makes it feel familiar on the road, being nimble enough to hustle through corners and enjoy out-of-the-saddle sprint efforts on tarmac. It isn’t overly tall, and the reach is noticeably shorter than on an out-and-out race bike, but not so short as to make you sit bolt upright in day-tripper fashion.

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The shorter reach is also very well countered by a clever rear end. As mentioned above, the Datum has clearances for 33mm tyres with 45mm mudguards, but Genesis hasn’t had to extend the chainstays. This has been achieved by shaping the seat-tube aero bike- style, although here it’s not to save watts but increase tread.

On the road this has a great effect. Some bikes designed for gravel feel a little pedestrian on blacktop, having stability in spades but lacking a bit of zing. The Datum feels quick, nimble even. This is no doubt helped by the impressive Challenge Strada Bianca 30mm tyres with their supple casing and slick treads. Fulcrum’s new wider Racing Sport DB wheels enhance the snappy feel. They aren’t light but they are smooth running, stiff and very quick to pick up.

When it comes to controlling your pace it’s down to Shimano’s all-new lower price point 505 brakes and STi lever units. The shifters are big and the Flat Mount brake units are considerably bulkier than either 685 or 785 units – but the performance is brilliant.

The floaty feeling on rough stuff can translate to a slightly energy-sapping ride on solid roads, but we didn’t find much else to fault

On a tricky rocky, clay-rich off-road descent, not exactly what the tyres were designed for, the brakes offered all the control we needed. They provided just enough pressure to control the bike without resorting to easily skidding on a slick surface. They were just as impressive on the fastest road descent, and thankfully the non-IceTech rotors remained straight, rub free and never became noisy once heated.

The Datum impressed us off road, the fork’s 65mm offset imparting just enough control over the rough stuff without having to resort to a slack head angle. Pushing speed on a fast gravel descent we had to think twice before hitting the sort of pace you can achieve on GT’s Grade, but not by much, and that’s countered by the Datum’s on-road poise.

The new chassis uses a thru-axle fork matched to a standard quick-release rear. We think that’s ideal, as up front the Datum tracks brilliantly when the going is both rough and smooth. At the back you can feel the carbon frame complying over rough ground. The floaty feeling on rough stuff can translate to a slightly energy-sapping ride on solid roads, so if you favour pro-like road machines, you may feel a little shortchanged. It’s certainly very comfortable, though, a carbon seatpost and suspension tricks generating extra compliance.

For a company that’s only ever produced one carbon bike before the Datum represents a hugely impressive debut. We can only imagine how much further Genesis will go in composite design after this.