Why the Genesis Datum was such a groundbreaking bike

British brand Genesis is probably best known for its genre-defining Croix de Fer gravel bike, or perhaps you remember its Volare steel-framed road bike fondly, but we’re turning our attention to a less-celebrated model that we think was equally notable in its way: the Datum.

> Genesis gives Croix de Fer “biggest update since it was introduced in 2008” 

The Datum came along for 2016 and was designed to be a faster and lighter version of the Croix de Fer. It was arguably the first British carbon fibre all-road bike, although we didn’t really know how to classify it back then. Although there were bikes around at the time, and well before, that fulfilled a similar brief – such as the Kinesis GF-Ti,  Kinesis Tripster, and early models from Mason Cycles – they were all made from metal.

The Datum was disc brake-equipped and although it was designed to ride fast over tarmac, it was built to handle other surfaces too. That said, it wasn’t a gravel bike.

> What is an all-road bike? A guide to this emerging road bike category plus a selection of the best

“The large volume road tread does certainly open up wider possibilities, but we feel the gravel bike label does imply specific usage on a distinctly US phenomenon,” said Albert Steward, Genesis Brand Manager at the time, and Datum designer.

Of course, the ‘gravel bike’ term has become widespread outside the US since then, but the Datum wasn’t that. It was more of an all-rounder.

“In reality, the Datum is really just a bike for riding around and enjoying yourself across a variety of terrain, both paved and unpaved, fast or somewhat more leisurely,” said Albert Steward. “It could be a gravel bike to some. In the same way, it could be a fast, comfy road bike to others.”

The Datum was built to a compact road geometry using the Genesis Equilibrium as the starting point (Equilibriums still appear in Genesis’ range). The frame was made from 24/30-ton carbon fibre and featured a BB86 press-fit bottom bracket, a tapered head tube (1-1/8in bearing at the top, 1-1/2in bearing at the bottom), and discreet mudguard mounts. The Datum would take 33mm-wide tyres. Okay, that would hardly raise an eyebrow these days – and it's certainly well short of gravel bike territory – but it was pretty generous at the time.

The seat tube was slightly cut away around the leading edge of the rear wheel. That might seem a bit strange on a non-aero bike, but the idea was to provide more clearance for a mudguard without having to increase the length of the chainstays (they were 420mm).

Genesis also reckoned that the cutout provided more comfort-inducing flex, and we all know how bike designers love to talk about ‘vertical compliance’. The skinny seatstays and 27.2mm diameter seatpost were designed to do a similar job. On the other hand, the down tube, bottom bracket, lower seat tube, chainstays and head tube were designed to provide a stiff platform for pedalling.

The carbon fork’s squared-off crown provided loads of clearance, and it was thru-axle for increased security. The rear dropout used a conventional quick-release skewer.

Genesis sized the frame to fit a bulky TRP HyRd cable-actuated hydraulic disc brake. You got mudguard mounts front and rear but no rack mounts. Genesis expected people to use a seatpack and framebags for carrying luggage instead.

There were three models in the range and we reviewed the £3,199.99 Datum 30, equipped with Shimano Ultegra Di2. It was outstanding.

“Few bikes deliver such a complete package as the Datum,” we said. “It’s fast and fun enough for summer riding and ready for the winter with mudguards and disc brakes, but what really sets it apart is the fabulously smooth ride quality.,”

“It’s at home on the road, with long-distance comfort aplenty, we said. “It’ll also tackle gravel paths, bridleways and even singletrack if you’re that way inclined.”

As for classifying it, we said, “Datum is a disc-braked carbon road bike range, with large tyre clearances. Don’t think of Datum as a gravel bike; more as a comfy, fast road bike with a versatile twist.”

That summed up the Datum.

Unfortunately, the Datum doesn’t exist in the Genesis range today. Times move on, but we still have a soft spot for this hugely capable bike that was loads of fun over all sorts of terrain.

Check out loads more Bikes at Bedtime here.