OPEN ONE+ Frame

OPEN ONE+ Frame Info

Open Cycles has an alchemist at the helm. Gerard Vroomen starts with what people want and he figures out better ways to make it happen. His One+ Frame is an super-light (890g for a size M, including the rear derailleur hanger) cross-country hardtail that balances stability and agility with plenty of lateral stiffness, vertical compliance, and wheel/tire options. Included with are lots of nifty ideas that seem so simple yet have never been done before.

Here’s one of those ideas. The bike works with two different wheel diameters. The small works with 27.5+ and 26, while the other sizes work with 29 and 27.5+. If you’re looking for fast-rolling, go with the bigger diameter. For the M & L frames, tires up to 29x 2.4” fit. If you’re looking to tame rough terrain, or find yourself pining for the protection, shock-absorption, and grip of fatties, then you can go with  27.5 x3.0”. For the S frame, you can use up to 27.5 x 2.4” or 26 x 3.0”.

They got to this point thanks to smart shaping as well as their trademark dropped right chainstay. This move material away from the crank, chain ring and (sometimes) the front derailleur and allows for more room on the inside as well as outside of that stay. They also embraced some new tech. Namely the Boost standard. The 3mm that they’re able to move rightward for the chain ring and cassette, and the 3mm they move leftward for the non-drive axle gives room for wider rims and wider tires. It also creates a better bracing angle and thus improves lateral stiffness. For wheels, it means stronger, stiffer hoops-you just need to get hubs designed for Boost.

Finishing off the hub design of the rear end is the ThruThread thru-axle dropout. Basically, the derailleur hanger is part of the threaded insert, which the thru-axle secures to. This made it easier to design the stays by the axle, and optimize for stiffness and light weight, as the frame is taking less of the stress. And bonus! they’ve made hangers for both standard derailleurs and Shimano direct-mount. Both come with the frame.

Atop the thru-axle is Open’s pre-bent Wire stays. They’re flattened in the vertical plane and fattened in the horizontal to maximize vertical flex and minimize horizontal give. It will eat up the vibrations that your fat tires can’t handle. They flow to the top of the seat tube where a zero-setback should be installed. The seat angle is designed for zero-setback posts and the post design is lighter, thanks to the smaller, simpler head. Seat tube diameter is 27.2mm, designed small for better flex, though the size is common enough that you’ll have no trouble sourcing a post.

BTW, they’ve put a pilot hole in the seat tube for the seat post. This way you’ll always be certain that you’ve got enough post inserted. Just look at the hole.

While the round seat tube was designed with all-round flex in mind, the top and down tubes were designed with lateral stiffness in mind. The top tube is flattened, like the stays, to put more material in the lateral plane. The downtube is wide, shallow, and squared on the sides. And the sides have been reinforced with high-modulus carbon to boot. This increases lateral stiffness while allowing for vertical comfort.

The head tube is designed for the integrated tapered IS42/28.6 | IS52/40 (1 1/8” to 1 1/2”), with the headset included. The bottom bracket uses the BB92 standard. Wider means more carbon, and the shell means you can use 24mm or 30mm diameter thru-axles.

Not surprisingly, the One+ is designed to route cables internally, with everything fitting. By that, 1x mechanical (10/11/12), 2x mechanical (10/11), Di2, even hydraulic shifting. Cleaner, prettier, less likely to mess up cables. If you go the Di2 way, the battery should go in the seatpost.

The geometry numbers found on the chart are based around installing an unsagged 100mm suspension fork with 44-46mm of offset. Any fork from 100-120mm can be used, but the taller forks will lay back the angles a bit and reduce bottom bracket drop.

The frame comes with: headset, seat tube collar, a Syntace X-12 thru axle (they think it’s the best on the market), two derailleur hangers, chainstay cable stop exit, bottom bracket cable guide, cable sleeves for inside the frame tubes, noise-reduction foam sleeves to put inside the frame tubes, two sets of bottle cage bolts, three Multi-Stop cable insert guides for the side of the head tube (to accommodate, 1x, 2x, and Di2), and a manual.
The Open Cycles One+ Frame is cross-country and beyond.