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Open U.P.P.E.R. AXS Build

  • The superlight U.P.P.E.R. with OPEN U-turn fork for flat-mount disc brakes
  • Force AXS with Eagle AXS Rear Mech
  • Simply add a pair of 650B MTB wheels and 2.1" tyres for full-on off road use
  • Unique groupset provides smooth reliable shifting




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Product Information

Open U.P.P.E.R. AXS Build

Just when we thought the OPEN U.P. was the perfect blend for road and offroad riding in one bike, here comes the brand new U.P.P.E.R. with a lighter weight frame, flat mounts for brakes and 12mm front axle to accommodate even more brake and wheel options. 

Full Specification


Intro: U.P. vs U.P.P.E.R.

U.P. (Unbeaten Path) and U.P.P.E.R. combine a performance-oriented cross/road geometry & parts with clearance for mountain bike tyres. So you can ride anywhere, and ride fast. Get out of town on asphalt, hit the gravel roads or switch to singletrack. The geometry gets you there fast; the big tyres make you unstoppable.

Tyre clearance

The U.P. fits mountain bike tires up to 2.1” wide. But you can also fit a 40mm cross tyre, or a 28mm road tyre, or anything else in-between (exact tire sizes depend on manufacturing tolerances and rim width, so this is a guideline. Always make sure you have 6mm clearance between tyre and frame). 

Crank clearance

Behind the bottom bracket, the chainrings, frame and tire all fight for space. And with the need to fit big mountain bike tires and narrow Q-factor cross/road cranks & chainrings, the U.P. presents the toughest possible packaging problem. Dropping the right chainstay moves it out of this crowded area, allowing it to be wider and therefore stiffer (a huge effect; with the same amount of material, twice the width will give you eight times the stiffness!).

TRCinTRS™ technology

“100% hi-modulus carbon”, “aerospace grade”, etc. Useless – and hopefully false (we’ll get to that) – claims meant to impress you. It’s not about high- or low-modulus, it’s about the right carbon in the right spot. And because the bike industry loves techie-sounding abbreviations, we’ll humour them and call it TRCinTRS™. Fact: stiffer carbon is more brittle. Strategically placed ultra-high-modulus carbon is a good idea. Making the whole headtube out of it when you have big impact loads is not!

Zero-setback seat tube

With a minimalist 27.2mm diameter, we maximize the flex in our seatpost & seat tube. This is especially a big plus on rough terrain. The seat tube angle is designed around the use of a straight, zero-setback seatpost rather than a regular seatpost setback (we’ve never understood those). Zero-setback posts are lighter, saving you another 10-30 grams (every little bit helps and you can then put that saved weight into a 500g saddle like the Brooks!).

Disc brake mounts

One of the key differences between the U.P. and U.P.P.E.R. is the disc mount standard. The U.P. uses post-mount, whereas the U.P.P.E.R. is designed for flat-mount. Open don't like how the bike industry keeps “inventing” new standards, so we always investigate if they are an improvement before we use them.

Bottom bracket

The U.P. uses the 386 EVO bottom bracket standard. The wide (86mm) BB shell is perfect to attach the dropped drive-side chainstay too. Furthermore, it fits most of the cranks on the market, from Shimano, Campagnolo and SRAM but also smaller brands like THM, Rotor and RaceFace. 386 EVO even allows for the installation of many mountain bike cranks. 



Frame: OPEN U.P.P.E.R

Frame sizes: S, M, L, XL 

Frame weight: 880g (Medium)

Fork: OPEN U-turn with 12mm thru-axle

Frameset: incl. frame, fork, seat tube collar, front thru-axle and spare rear derailleur hanger

Groupset: Force AXS 1x Groupset with Eagle AXS Rear Mech

Wheels: Zipp 303S Carbon 700c with Panaracer GravelKing SK Tubeless Tyres

Handlebars: Easton EA70 Road or AX Gravel Bars (choice of width)

Stem: Easton EA70 Stem (choice of length)

Saddle: Specialized Romin Evo Expert Gel

Tyres: Specialized Pathfinder 700s or Maxxis Beaver 650b-  tubeless set up

Colour: Matte black

Incl. in box: Frame, fork, headset, seat tube collar, front & rear thru-axle, 2 rear derailleur hangers, 1 removable front derailleur mount, cover bolts for front derailleur mount posts, 3 MultiStops (2x, 1x, Di2), chainstay cable exit stop, BB guide, cable sleeves, noise-reduction foam sleeves, bottle cage bolts, manual


Chainring Information

Chainring fit: NOTE: For single chainring set-ups, OPEN recommend flat rings, not offset rings, for the best chain line. For "regular" oval rings, deduct 2 teeth from the below spec. For extreme oval rings, who knows.

Max inner ring: 36t

Max outer ring: 50t (more is overkill with the bigger tires)

Max single ring: 46t (offset rings like SRAM 1x)

Max single ring: 50t (flat rings, better cassette alignment)

Headset std: Integrated Tapered IS42/28.6 | IS52/40

Seatpost Ø: 27.2mm

Rear axle std: 142x12mm (X-12) thru axle (Syntace for U.P., Carbon-Ti for U.P.P.E.R.)
Brake std:

Front: direct-mount flat-mount for 160mm rotor; Rear: flat-mount for 140mm rotor (160mm with adapter)

Cable routing: Internal via exchangeable MultiStops for 1x10/11, 2x10/11, Di2

Bag mount: 100mm front-post-to-bearing-bore-edge