We bring you first rides on a couple of quite different gravel bikes: BMC’s URS ONE and the Vitus Substance CRX
£8999 Unlimited pleasure on BMC’s new gravel bike
BMC’s first gravel bike brings together the Swiss company’s extensive tarmac and dirt design skills to produce the URS. Its unusual name is an abbreviation of unrestricted, a comment on the UCI’s current lack of design rules for gravel and all-road bikes. It’s also short for Ursa, or bear, and Urs is a common Swiss male name, a bit like Dave is here…
The frame is nearly bereft of a logo but it’s unmistakeably BMC, including elements of the latest Roadmachine and BMC’s mountainbike big-wheel concept, plus some unique URS features. The URS range consists of four 1x drivetrain models all sharing identical carbon framesets with BMC’s progressive Gravel+ geometry. This means short 425mm chainstays, a 70-degree head angle, correspondingly long wheelbase and a short stem, positioning it squarely between road and mountain bikes.
With an impressive, claimed medium size frame weight of 1050g in its lightest finish, plus another 550g for an uncut fork, the URS doesn’t pull any performance punches, and our medium test machine weighed just 8.22kg. Its dedicated carbon layup and specific tube shaping was determined using BMC’s new TCC (Tuned Compliance Concept) Gravel software, and integrates the Roadmachine’s D-shaped carbon seatpost and the seatstay-splitting MTT (Micro Travel Technology) system.
The soft-tail MTT system has stabilising rigid internal rods, which are fixed at one end only within the stays and surrounded by an elastic material. It’s not what is commonly called an elastomer, but is sourced from the motor industry and is impervious to degradation from sun, weather and age, weighs around 80g and isn’t
cheap. MTT provides 10mm of travel for greater compliance and improves power transfer and traction on rough surfaces.
Although there’s clearance for 700c tyres that measure 45mm, the bike’s geometry was developed around 40mm tyres and allows for some sag due to low tyre pressure. It’s also compatible with the Fox 32 SC AX gravel suspension fork, and a dedicated headset stopper to be used with it is included with the bike. For greater tyre volume the URS will accept 650b wheels with tyres up to 47mm.
In keeping with the URS’ hardcore adventurous aspirations, there are extras. The carbon fork’s dropouts have rubber covers, which BMC terms Rock Sox, protecting the fork legs from potential damage when resting on the ground during wheel removals; there’s also routing for a front hub dynamo through the fork and head tube.
The driveside chainstay and lower part of the down tube are protected by rubber patches, and clear impact-resistant Helicopter tape covers the rest of the down tube’s underside. The frameset’s all-gloss finish makes it easy to clean, but to keep muck off there are integrated mounts for full mudguards (with 40mm tyres), or the supplied DFender under saddle ’guard, as seen on the Roadmachine, can be added. A shim allows the fitting of any 27.2mm round dropper post to the D-shaped seat tube, a third bottle cage mount beneath the down tube caters for the long haul rider and the top tube has a fuel bag mount for food or accessories.
The entry-level model has a conventional stem, but the others come with BMC’s integrated ICS stem, which keeps hydraulic hoses and electronic shifting wires hidden internally. The gravelspecific stems have 0-degree rise, and come in lengths of 55mm or 70mm, depending on frame size. All models have 180mm front and 160mm rear disc rotors for absolute stopping power, and 38- or 40-tooth chainrings, but although there is clearance for a 48-toothring, there is no front derailleur mount.
Our medium bike’s 70-degree head angle and 55mm stem took a few miles to get used to on the
road, initially feeling busier and more prone to wander, but it soon became second nature. The URS has a very forgiving, docile nature, which translates into great poise and confident line control on very technical woodland or rocky singletrack, thanks to its quick steering. At 40mph on a sustained dirt descent, its stability was impressively calming but, when needed, the URS reacts with a sharp, snappy response and its low weight boosts its agility.
Large, low pressure tyres will have a significant effect on the ride feel of any bike, but the URS’s ride quality doesn’t stop there. BMC’s D-shaped seatpost is very effective on the road, because its flat back allows it to flex more readily in a defined way. Here, in conjunction with a comfy WTB saddle, 42mm WTB Resolute tyres that measure 45mm on the DT Swiss wheelset and the MTT system, the URS’s rear-end comfort is simply extraordinary.
The MTT’s suspension travel helps the rear wheel to gain more traction while extending your seated duration by stifling impacts that might otherwise make you stand up, both of which positively affect speed. Up front, the Easton carbon bar increases the ride-smoothing ability of the carbon fork and 42mm tyre. Test rides on the URS encompassed rocky sections, tarmac, grassland, gravel, dirt, man-made obstacles, roots and mud, but we didn’t suffer any jarring.
Our URS ONE is supremely specced with SRAM Red eTap AXS wireless 12-speed in mullet build (the rear cassette comes from MTB, so the backend gearing is much bigger). Up front is a businesslike 38 ring, with SRAM’s Eagle AXS rear mech and huge 10-50 Eagle cassette bringing the party at the back. Such a wide gear spread may seem unecessary, but it’s essential when exploring the URS’s extensive capabilities and the only mildly niggly gap we felt was at around 20mph on false flats.
The DT Swiss GRC 1400 Spline wheelset is designed for larger volume gravel tyres, with generous internal width ensuring great sidewall stability at low pressures. Their 42mm depth adds some aero efficiency to excellent rigidity, and their claimed 1600g weight balances responsiveness with rugged durability.
Whether cruising rolling gravel trails, surfing a loose wooded descent, climbing steeply at walking pace or flying along at road bike speeds, the URS is easily the most comfortable, technically proficient and universally capable all-road or gravel bike yet. It’s not only Unrestricted in design terms, but also in its cycling possibilities.
Its stability is calming, but, when needed, the URS reacts with a sharp, snappy response
Has BMC created the most technically proficient gravel bike yet?