Open UP gravel/adventure frameset 2017

Open's distinctive, bright orange UP (which stands for Unbeaten Path) combines a light and stiff carbon fibre frame and fork designed explicitly to perform on dirt and gravel with huge tyre clearance, so you can fit just about any tyre you want including mountain bike options. It's packed with nicely executed design details, but it does command a high price.

The Open is a bike you can ride pretty much anywhere. The same can be said of a growing number of gravel and adventure bikes, of course, but where the Open scores highly is in that huge tyre clearance. Everything from 28mm slicks for road riding to 38-40mm gravel-specific tyres, 47mm-wide 650Bs and even 2.1in mountain bike knobbly tyres fit inside the cavernous clearance front and rear.

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I found a 38-40mm low profile gravel tyre like the new Hutchinson Overide or Panaracer Gravelking the best fit for the sort of riding I was doing with the Open, predominantly off-road with interlinking road sections. That's the beauty of the Open, you can build it up with the tyres that suit your riding style and intentions.

Ride and handling

Make your tyre choice and take the Open off-road onto gravel roads or narrow bridleways and the bike instantly feels at home. The geometry gives the bike a measured stance, with the slowish steering ensuring it never feels nervous or twitchy when the tyres are scrabbling for grip or you're screaming down a loose and fast descent. While the stability makes it an easy bike to travel fast across rough terrain, there's a lively edge to the Open's handling when you ask for it, and it nips and tucks through corners and carves beautiful turns with solid ease.

Where the geometry really shines is in just how far you can push the Open in tricky and technical terrain. Its limits far exceed that of a cyclo-cross bike, especially if you go to as wide a tyre as you can fit in the frame, and there's no need to tip-toe over roots or rocks, you can charge full bore through and over them. I was able to ride many of my easier mountain bike trails on the Open, not something I've ever tackled before on a road bike.

It's a comfortable ride too, for long periods in the saddle. The skinny stays and 27.2mm seatpost help to provide noticeably more isolation from trail chatter and vibrations than an aluminium alternative such as Mason's Bokeh, to pick one example. It really looks after you on long rides, and you'll feel as fresh as can be expected when riding a lightweight carbon bike with no suspension other than large volume tyres across rough terrain...

It's not only in off-road situations that the Open shines. Swap the knobbles for slick tyres – I went for a 28mm – and its road riding manners prove to be more than adequate for long rides. It's not a full-fledged road bike, but the carbon frame and fork, along with the oversized bottom bracket and large profile chainstays and down tube, give the Open a high level of stiffness. This makes it responsive when you inject some pace into proceedings, and it fairly belts along the road. It's quick enough that you can keep up with your buddies on road bikes most of the time, though some deep-section wheels would certainly add some extra oomph.

Transitioning from the road to off-road, with a focus on exploring the 'unbeaten path' – to use the bike's full name – is what it does so well. With the right tyre you can ride anywhere and over everything and not feel overly compromised at any point. You're not constrained by the terrain and this results in huge smiles – it's the most fun bike I've reviewed in ages.

Frame details

The full carbon fibre frame and fork are beautifully finished, and not just because of the orange paint... Designed by ex-Cervelo founder Gerard Vroomen (also responsible for the more recent 3T Exploro), the 55cm frame here weighs 1,150g, which isn't bad for a bike designed for rugged off-road riding.

It's packed with interesting features and nice details and really does stand out from the crowd (and not just because it's bright orange...). By far the most intriguing is the dropped drive side chainstay. It's shaped this way to provide the necessary tyre and chainset clearance while keeping the Q-factor narrow and the chainstays short. It's something we've seen on mountain bikes, and a few other road bike brands are starting to adopt a similar approach.

Other details include a tapered head tube, BB386 EVO bottom bracket and full internal cable routing, compatible with any combination of mechanical or electronic gears, hydraulic brakes and 1x or 2x chainsets thanks to Open's MultiStop system of inserts.

The down tube has flattened sides, said to improve frame stiffness, while the seatstays are pencil thin which, in unison with the 27.2mm seatpost, should provide a reasonable level of comfort. To ensure the correct amount of seatpost is installed, there's a tiny SafePost Pilot hole near the top of the seat tube.

It's a disc brake-specific frame using the post mount standard and thru-axles – 142x12mm at the back and 15x100mm at the front.

This is the only area where the Open UP has been slightly overtaken by the rapidly changing standards in the time since it was launched, with flat mount and 12mm front thru-axles increasingly looking likely as the de facto choice. Still, there's nothing actually wrong with post mount or 15mm thru-axles of course.

As well as two regular bottle cage mounts, there's a third on the down tube, which would also serve as a handy place for a tool keg.

There are also two bolts on the top tube for fitting a top tube bag but actually getting hold of a compatible bag provide a tad tricky, and with the prevalence of strap-on top tube bags, I simply removed the bolts, slapped on some helicopter tape, and used a top tube bag.

There's a lot of versatility baked into the Open UP, but the one detail it's arguably missing is the addition of mudguard mounts that would ensure it meets the needs of the all-weather British cyclist.

My build

This is a frameset review because Open doesn't sell complete bikes, so I won't go into too many details on the equipment. Suffice to say, I used a SRAM Rival 1 groupset that is an ideal option, with the simplicity of the single ring drivetrain (I chose a 38-tooth) and a wide range 11-36 cassette offering all the gearing I needed – especially when it came to tackling the climbs of the Dirty Reiver course. You can, of course, fit a much wider range cassette.

The low-focused gearing was fine off-road and adequate on the road, but you do spin out more easily on descents. A switch to a bigger chainring is an easy solution – or you could simply freewheel when it gets that fast and use the descents to recover ready for the next climb.

> Struggling with your gears? The lowdown on getting lower

I swapped the rest of the parts out loads during the test, changing wheels a few times but settling on the excellent Praxis RC21 carbon tubeless wheels. They have a wide profile rim that works nicely with wide tyres, tubeless installation is easy, and they proved durable and tough.

The rest of the kit included a carbon Bontrager bar, Ritchey stem and Enve seatpost, plus a Fabric saddle and Fizik bar tape. I used an Apidura framebag for the Dirty Reiver and covered the frame in helicopter tape to prevent it from getting scratched.

Rivals

There are a lot of rivals operating in the same gravel/mixed terrain space as the Open UP, and more affordable complete bikes with similar purpose and poise, such as the £2,900 GT Grade and £2,600 Specialized Diverge. At £2,000 the complete Raleigh Roker Pro is less than the Open UP frame and fork.

> Buyer's Guide: 18 of the best 2017 gravel & adventure bikes

The £3,100 Mason Bokeh runs the Open UP close in terms of performance, but the Open UP edges it in pure agility and smoothness.

Verdict

If you look at the Open UP as two bikes in one with just a change of tyres or wheels, the premium price tag is a little easier to justify. Putting the price to one side, the UP is a beautifully made and finished product, packed with smart design features and offering a level of performance for off-road and mixed terrain riding that ensures it's one of the best options in the gravel/adventure category.

Verdict

Superb multi-terrain adventure and exploration bike – if you can afford it