Open One+ first ride review£2,750.00

Ultralight XC frame puts old school shape on nu skool wheels

Open Cycles co-founder Gerard Vroomen was one of the team behind the rise of road brand Cervélo but now he concentrates on small scale production of bikes he wants to ride himself.

  • Frame: Open TRCinTRS carbon
  • Fork: RockShox RS-1 120mm
  • Wheelsize: 27.5+
  • Drivetrain: SRAM XX1 Eagle
  • Brakes: SRAM Level Ultimate 180/160mm
  • Head angle: 70.5 degrees
  • Seat angle: 71.5 degrees
  • Reach: 435mm
  • Weight: 9.3kg (20.8lb), size large

Pressing the Boost button

SRAM Eagle doesn’t just increase gear range, it shifts better and runs smoother too
SRAM Eagle doesn’t just increase gear range, it shifts better and runs smoother too

The first One 29er was originally ready to drop in 2015, but a last minute switch to the new Boost standard means the One+ has only just appeared.

Unlike most plus-compatible frames (even the carbon ones) it’s still a super light frame, with our large sample coming in at 910g. Practical detailing is fantastic too.

The 148mm Syntace X-12 axle screws into very neat ‘ThruThread’ dropouts that also lock the replaceable gear hanger into place. A broad BB92 press-fit bottom bracket and dropped driveside chainstays give room for 29x2.4in or 27.5x3in tyres on wide rims.

MultiStop frame inserts mean you can run double chainring, single chainring, ‘stealth’ dropper post or Di2 control lines internally and still get super neat exit/entry ports. There’s even a SafePost peephole on the seat tube to make sure you’ve got enough seat post overlap and the seat angle is slackened slightly to work best with a lighter inline rather than layback post.

Eagle chainrings get a radical, load-sharing tooth profile based on studying worn out rings
Eagle chainrings get a radical, load-sharing tooth profile based on studying worn out rings

The TRCinTRS moniker for its carbon construction stands for The Right Carbon in The Right Spot, a direct jibe at manufacturers who claim to use the same super stiff but fragile ultra-high modulus carbon throughout their frames. Open does use UHC carbon strips on the oversized ‘Flat-Out’ down tube for a surgically precise steering connection between head tube and bottom bracket but it’s part of a carefully balanced lay-up of different fibres and sheets.

Out back the ‘Wire’ stays are super thin vertically and pre-curved so they flex easily under impact loads. Load them up from the side though and their broad structure maximises cornering stiffness and traction feedback.

I'm well aware that pretty much every frame claims to be both comfortably smooth and power-stomp-stiff these days but the Open genuinely lives up to that promise. It’s smooth even with conventional small volume 29er tyres and with plus tyres at sub-teen pressures it’s a sticky traction micro suspension bike.

While it’s not brutally power efficient, if you pick an over adventurous gear when you’re trying to get the jump on a race pack it’ll still kick hard to heave the ratio into rhythm and make the move stick.

I actually flipped the USE riser bar ‘upside down’ to keep hands low over the tall fork
I actually flipped the USE riser bar ‘upside down’ to keep hands low over the tall fork

A wheel dilemma

Unsurprisingly that’s amplified massively if you fit it with a lightweight 29er wheel and tyre set-up. If you’ve got the money (a fair presumption if you’re building up a €3,000 frameset) you shouldn’t have trouble knocking a kilo off the overall weight in the process too.

Unfortunately I couldn’t get a suitable custom Predictive steering front hub, Boost rear hub wheelset in time for Relentless. Plus I didn’t fancy doing a fork swap as well as a wheel swap in the middle of the night. Having that extra margin of error that plus tyres bring in corners or rocky situations literally reduced the impact of that fatigue on my ‘not thriving, surviving’ laps too.

The versatility to run the One+ in either format is also a bonus for racers who sometimes like to pull baggy shorts on over their skin suits.

The ability to blast the sweeping singletrack corners of Fort Bill was a definite Plus on the Open
The ability to blast the sweeping singletrack corners of Fort Bill was a definite Plus on the Open

The geometry of the One+ means that skin suit is never going to be far under the surface of its ride character though. While Open has built it buff enough to work with a 120mm fork, that leans the already slack ‘inline post specific’ seat angle too far back for confident seated climb steering. In fact I ended up running the USE ‘riser’ bar upside down to keep my hands low and connected.

It also jacks up the bottom bracket height and, combined with the lack of twist stiffness in the RS-1 fork, created a vague front end feel that I had to learn to trust rather than having an implicitly tactile connection.

Switching to a 100mm stroke Fox 32 fork certainly feels better balanced as a complete bike, but in a decidedly nineties way rather than a contemporary boosted confidence, 60-something head angle style.

Given the bold move Open has made with the dual wheel capability and potential trail versatility I personally think that’s a shame. However, having watched UK racing stay resolutely traditional in its handling tastes and been shocked to see there are still more V brakes than helmet peaks on display at a typical European race I can see why Gerard and co have kept the geometry this way.

Open One+ early verdict

Superbly detailed, super light, dual wheel rocket, but retro race geometry.

This article was originally published in What Mountain Bike magazine.

Guy Kesteven

Freelance Writer, UK
Guy started filling his brain with cycle stats and steaming up bike shop windows back in 1980. He worked the other side of those windows from '89 while getting a degree in “describing broken things covered in mud" (archaeology). Dug historical holes in the ground through the early '90s, then became a pro bike tester in '97. Guy has ridden thousands of bikes and even more components the world over since then and can remember them all in vivid, haunting detail. Can't remember where the car keys are, though.
  • Age: 45
  • Height: 180cm / 5' 11"
  • Weight: 68kg / 150lb
  • Waist: 76cm / 30in
  • Chest: 91cm / 36in
  • Discipline: Strict sadomasochist
  • Preferred Terrain: Technical off-piste singletrack and twisted back roads. Up, down, along — so long as it's faster than the last time he did it he's happy.
  • Current Bikes: An ever changing herd of test machines from Tri bikes to fat bikes and everything in between.
  • Dream Bike: His Nicolai Helius AM custom tandem
  • Beer of Choice: Theakston's Old Peculier (not Peculiar)
  • Location: Yorkshire, UK

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