Introduction

In 2012 we introduced the O-1.0; the world's first sub-900 gram hardtail. It was the perfect XC racing machine as our customers (you!) have proven that time and time again, from World Cup cross country races to Cape Epic wins (without sponsorships!)

By mid-2015, we were almost ready to introduce the ONE, but a delay in manufacturing and the introduction of the Boost standard made us change our mind. Boost increases wheel & frame stiffness and improves tire clearance. This was too good a chance to pass up, and so we reworked the frame completely into what is now the ONE+

The ONE+ is still that zero-compromise XC racing machine; our customers expect this from us and so we made absolutely no compromise here. Boost, a BB92 bottom bracket and our Thru-Thread thru axle increase drivetrain stiffness further, while new Wire-stays improve vertical compliance & traction. A dozen more tweaks and updates make the ONE+ a much, much better frame than we ever thought possible.

And then the bonus: Boost gave us enough space for 29x2.4” tires and tons of mud clearance, perfect for the ever more demanding XC courses. And similar to what we did on the U.P. the ONE+ also provides space to put in a 27.5x3.0” tire! While there are other frames that offer to fit both wheel sizes, they are usually heavy and not that much fun. Because the ONE+ has a zero-compromised XC frame that is still sub-900 gram, it’s super light not only as an XC racer but also as a 27.5+ tire go-anywhere bike. This makes it not only an interesting option for tough, fun rides but even for very demanding XC courses. More tire, more fun, more speed!

Tire philosophy

The ONE+, like its predecessor the O-1.0, is all about agile handling and efficient power transfer in a super-light package. For the new design we made two small tweaks:

1)  We included wider 2.4” tires into the mix, as tires in XC are creeping up in width to deal with the ever more challenging courses.
2)  For the smallest size, we changed from 29er to 27.5” tires. This allows us to get the front end lower, which was a frequent request for the O-1.0 in size S. There’s only so low you can go over a big 29er front wheel. The 27.5” gives us the space to create the perfect geometry for handling and fit for these customers. This also means that for the Plus tires, the size S uses 26+ tires instead of 27.5+ tires.

With the cross country geometry dialed in, we focused on a third, much tougher change: how to offer the option of fitting 3” wide tires onto such a cross-country racing machine without compromising the handling.

We faced a similar problem for the U.P. model, and the solution is also similar. Had we simply made space in the frame for 29er tires that are 3” wide, the resulting bike would have been a disaster for two reasons:

1)  If the geometry works well for cross country tires (2.0-2.4”), going all the way to 3.0” means the overall size of the wheel becomes much bigger, so the bike sits higher, the trail increases and the handling is compromized.
2)  To accommodate these bigger tires, you need longer chainstays, a bigger fork, all things that make it a worse cross-country bike.

Obviously this was not an option for us; we do not wish to compromise the cross-country handling of the frame at all.

So we went a different route. For the 3.0” tires, we went with a 27.5” rim (26” for size S). The smaller radius of this rim in combination with a bigger tire renders the same overall wheel size as a bigger radius rim with a smaller tire.

Same overall wheel size, same handling, no compromise. That simply doesn’t work with 29x3.0” Plus tires, only with 27.5x3.0” Plus tires. Here it is in numbers:

Tire sizeWheel radius
29x2.1”367
27.5x3.0”363
29x3.0”387

Boost

Lots of confusion in the mountain bike world nowadays, between three wheel sizes, several axle standards, Fat & Plus tires, Boost, etc.

So let’s talk about Boost. It’s really quite simple, Boost moves the chain outward by 3mm without changing the Q-factor (pedal stance) of the crank. It basically uses up the space created when high-end bikes stopped using triple cranks.

Also moving the cassette out 3mm plus another 3mm on the disc brake side means the rear wheel axle grows from 142 to 148mm. This improves the angles for the spokes to create a stronger, stiffer wheel. Great for big 29er wheels but really a good thing for every wheel size.

Bottomline: same pedal stance/Q-factor up front for good pedalling efficiency, wider spoke stance in the rear for stiffer, stronger wheel builds. If you want, you can also do the same trick in the front with a Boost front hub (110mm vs 100mm) but that’s optional.

Why do we add Boost to this frame? Because it adds stiffness to the build, because it works well with the wider rims that we prefer and because it creates more tire clearance between tire and chain. Aside from these advantages, there really aren’t any drawbacks now that all manufacturers have started making their components in Boost versions.

Dropped chainstay

To create space for bigger tires, the ONE+ features OPEN’s trademark dropped chainstay. A clean and simple method to move the chainstay away from the most crowded real estate on a frame and towards an area where we can boost the chainstay size for the most efficient power transfer.

TRCinTRS™ technology

“100% hi-modulus carbon”, “aero-space 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 humor 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!

The best lay-up is not 100% of one modulus; it’s a blend. We use the highest modulus (stiffest) carbon of any bike manufacturer where we can, and tougher grades of carbon where we must. That’s how our frames are both light and durable.

Wire-stays

The rear triangle has to provide lateral stiffness for an efficient drive train, but vertical compliance for better comfort. The ONE+ features chainstays and seatstays that are extremely thin vertically to provide that compliance, while their lateral width and layup ensure rock-solid propulsion.

The seatstays are pre-curved so they can absorb even small bumps very quickly. But lay the bike into a turn and you’ll notice how stiff they are laterally. Truly the best of both worlds.

Flat-out downtube

The downtube is the key for stiffness, connecting the steering center of your frame with the drivetrain. The flat-out downtube’s characteristically flat outside faces allow us to strategically place strips of ultra-high modulus carbon far away from the center plane. The stiffest carbon exactly where it matters, guaranteed!

Zero-setback seattube

With a minimalist 27.2mm diameter we maximize the flex in our seatpost & seattube. This is especially a big plus on rough terrain. The seattube angle is designed around the use of a straight, zero-setback seatpost rather than a regular seatpost with setback (we’ve never understood those). Zero-setback posts are lighter, saving you another 10-30 grams (every little bit helps).

Fully-internal cables/hoses

External cables & hoses collect dirt, risk getting stuck behind objects (particularly expensive with electronic shifting) and frankly, they are ugly. So the ONE+ runs them internally.

With our proven MultiStop design, you can customize the frame for 2x10/11, 1x10/11 and Di2 shifting. Just pick the right insert.

ThruThread dropouts

Most thru-axle frames are heavier than quick-release frames. Extra carbon for the dropouts, heavy hangers, and the axle itself. But they are stiffer, So what do you want most? The answer for most people is “both”, and so we introduce the first frames that combine a thru-axle with a lower weight. How?

The ThruThread design uses the same threads that hold the thru-axle to lock the derailleur hanger into the frame. Simple, light, effective.

We didn’t just redesign the dropout, the entire seatstay and chainstay design is optimized with the added stiffness of the thru-axle in mind. For the thru-axle itself, we recommend the stiffest design available, the Syntace X-12, but you are free to use a different 12mm thru-axle if you want.

For the derailleur hanger, we offer two options: standard and Shimano direct. Both are included in each shipment.

SafePost™ Pilot hole

Seatposts usually indicate a minimum insertion dimension. That keeps the seatPOST safe, but it’s also important that the seatTUBE is supported properly. The minimum insertion for that is indicated by the SafePost Pilot hole.

Bottom bracket

The ONE+ uses a 92mm bottom bracket standard. This allows you to directly mount a Shimano or SRAM 24mm crank in the frame (the wider BB shell replaces the outboard bearing cups, essentially integrating them into the frame structure).

You can even fit cranks with wide, 30mm axles by using a special super-light bearing set (for example the THM M3 and RaceFace SL cranks) for the stiffest, lightest possible set-up.

Geometry

PLEASE read this before you jump into the numbers, so at least they make sense:

  1. The geometry is based on an unsagged 100mm suspension fork
  2. The size Small is designed around smaller wheels and hence a shorter fork. If you size by stack & reach, this doesn’t matter as they are independent of wheel size. But if you look for example at headtube length, you will see “strange” things like the Small having a longer headtube than the Medium. That’s not because the Small is taller, but because the whole headtube starts lower because of the smaller wheels.
  3. The ONE+ is designed around narrow 29er cross-country tires and wide 27.5” “semi-fat” tires. Both have very close outside wheel diameters so the geometry doesn’t really change between one or the other. Of course there will always be small differences from one tire to the next, a 2.1” tire from Schwalbe has different dimensions (in width and diameter) than a Continental or WTB. And of course a 2.4” tire will be slightly different from a 2.1” even if the make and model are the same. ll these dimensions are also affected by rim width. For the handling, that all falls within the range that we design for, but you do have to realize that for example standover height is slightly effected by this. This is obviously not unique to the ONE+, this applies to any bike.
  4. Standover height is measured to the top of the toptube directly above the bottom bracket and depends slightly on the exact tire size used.


size
standard
wheel
semi-fat
wheel
stack
reach
headtube
angle
seattube
angle
fork
axle-crown
headtube
length
toptube
length
seattube
length
BB
drop
rear
center
front
center
wheelbase
standover
height
S
27.5"
26"
584
401
71.0°
73.0°
487
102
576
420
40
423
635
1056
710
M
29"
27.5"
615
419
71.4°
72.5°
506
97
602
445
57
440
655
1092
752
L
29"
27.5"
647
436
71.4°
72.0°
506
135
643
500
52
440
684
1121
809

Specifications

Frame:OPEN ONE+
Frame sizes:S, M, L
Frame weight:890g (size M includes RD hanger)
BB std:BB92 PressFit
Recommended fork:100-120mm travel, 44-46mm offset
Crank std:Boost 1x or 2x (for 24mm or 30mm axles depending on crank brand)
Tire fit for frame:29x2.4” and 27.5x3.0” for size M & L
27.5x2.4” and 26x3.0” for size S
Headset std:Integrated Tapered IS42/28.6 | IS52/40
Seatpost Ø:27.2mm
Rear axle std:Boost 148x12mm thru axle
Rear brake std:Post mount for 160mm disc
Cable routing:Internal via exchangeable MultiStops for 1x10/11/12, 2x10/11, Di2
Incl. in box:Frame, headset, seattube collar, rear thru-axle, 2 rear derailleur hangers, 3 MultiStops (2x, 1x, Di2), chainstay cable exit stop, BB guide, cable sleeves, noise-reduction foam sleeves, bottle cage bolts, manual
Frameset Price
(excl. sales tax)
$3,200 USD

Comments & Questions

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OPEN
Based on the geometry of the ONE+, is there a minimum stem length for your frame? I used to run a 30mm stem on my other bike, but is that appropriate for an XC bike such as this?
Post #1 of 22. Posted by Putra on 03-May-2016 12:19:37 GMT [0<--639]
OPEN
You can if you want to, but probably when you pick the right frame size you'll end up with something a bit longer. But handling-wise, we have very agile steering so even with a super short stem, it is quite nice and not as sluggish as other bikes would be.
Post #3 of 22. Posted by Gerard Vroomen on 10-May-2016 14:36:28 GMT [639<--653]
OPEN
How does the chainstay length affect the handling? For me 440 mm seems a bit too long.
Post #2 of 22. Posted by on 09-May-2016 09:04:41 GMT [0<--650]
OPEN
Chain stay length affects stability and weight distribution. We've tested quite a range and the 440mm for the M and L in combination with the 29er wheels makes not only theoretical sense but also is what we prefer on the trails. Of course I say this in combination with all our other geometrical decisions, it's not like 440mm is good or bad in itself, it's how it works in combination with our head tube angle, our fork rake, etc to create that agile steering.
Post #4 of 22. Posted by Gerard Vroomen on 10-May-2016 14:45:46 GMT [650<--656]
OPEN
will it work with 120 mm fork?
Post #5 of 22. Posted by on 17-May-2016 11:45:39 GMT [0<--680]
OPEN
Yes it will.
Post #6 of 22. Posted by Gerard Vroomen on 17-May-2016 15:58:32 GMT [680<--681]
OPEN
Gerard: I've always admired your work with Cervelo--outstanding technical achievement in so many ways--and always wondered if you'd ever find the time to turn your attention to mountain biking. You've solved one of the principal challenges of road bike design--taking advantage of aerodynamics without materially impacting other key elements, such as weight and handling. Now I'm wondering whether you'll take on one of the key design challenges of mountain bikes: Giving the rider the advantage of full suspension to cope with technical race courses. Again, without overly impacting other key design elements. Seems like a useful challenge to solve, a difficult one, and therefore one worthy of your skills.

Regardless, you have my

Best,

Brad
Post #7 of 22. Posted by on 28-May-2016 15:39:35 GMT [0<--705]
OPEN
Hi Brad, we've been working on a full suspension frame for a long time and continue to. It will be ready when it's ready :-)
Post #8 of 22. Posted by Gerard Vroomen on 30-May-2016 12:16:47 GMT [705<--706]
OPEN
Can I run a 120mm fork on this frame?
Post #9 of 22. Posted by on 08-Jul-2016 20:24:51 GMT [0<--786]
OPEN
Yes you can. 100 or 120 mm both work well with the frame.
Post #10 of 22. Posted by Gerard Vroomen on 09-Jul-2016 16:44:10 GMT [786<--787]
OPEN
I have a question about the Open O-1.0 what are the specs the rear axle?
Post #11 of 22. Posted by Felix7 on 19-Jul-2016 05:15:49 GMT [0<--805]
OPEN
The O-1.0 had 135mm quick release. The ONE+ has 142 x 12mm thru-axle.
Post #14 of 22. Posted by Gerard Vroomen on 01-Aug-2016 23:04:24 GMT [805<--834]
OPEN
142x12??? The One+ is boost148?
Post #16 of 22. Posted by Adrian on 04-Aug-2016 11:00:43 GMT [834<--847]
OPEN
Sorry, typing too quickly. Yes, 148x12.
Post #18 of 22. Posted by Gerard Vroomen on 07-Aug-2016 10:50:30 GMT [847<--852]
OPEN
Hi,

what is the distance from upper end of the seattube to the SafePost Pilot hole? So: how deep the seatpost have to be into the seattube?

Thanks
Post #12 of 22. Posted by on 31-Jul-2016 17:03:51 GMT [0<--830]
OPEN
100mm
Post #13 of 22. Posted by Gerard Vroomen on 01-Aug-2016 23:03:34 GMT [830<--833]
OPEN
Can I use a powermeter on the left crank arm on the Open One +. And if yes which crank with powermeter will fit?
Post #15 of 22. Posted by on 03-Aug-2016 22:26:54 GMT [0<--843]
OPEN
Unfortunately there are so many variables with power meters that we cannot give you a straight yes or no answer. The Rotor InPower fits, as do other power meters that have the sensors inside. for outside "pod" style cranks, your store will have to try and see.
Post #17 of 22. Posted by Gerard Vroomen on 07-Aug-2016 10:49:55 GMT [843<--851]
OPEN
Hi Gerard, I have a question regarding crank length for mountain bikes - a few years ago, a switch down to 170mm on my road and cross bikes had a huge benefit in terms of my comfort through opening the hip angle.
Given that a mountain bike position will inherently have a relatively open hip... is there a logic to keeping crank lengths the same across all bikes, or trying to gain leverage by riding a longer mtb Crank (ex. 175mm)?
I would love to hear your thoughts. Thanks in advance!
Post #19 of 22. Posted by on 14-Aug-2016 15:08:58 GMT [0<--869]
OPEN
Looking at the available research, crank length seems to not follow any logical rules, so I can't possibly give you a correct answer. Trial and error is really all that works. However, you are correct that if your hip angle is a concern, it will be much more open on the mtb anyway so you wouldn't need a short crank to accomplish that. You could have a much, much longer crank and still have less of an acute hip angle.
Post #20 of 22. Posted by Gerard Vroomen on 17-Aug-2016 00:00:13 GMT [869<--872]
OPEN
Can i just say, as someone who's worked for multiple major bike brands, kudos for the amount of tech and the explanations as to the why's and how's you've given. showing roll outs for various wheelsizes? awesome. all of the geo FAQ's? Awesome. people should be fired up to buy your bikes.
Post #21 of 22. Posted by on 22-Aug-2016 16:18:27 GMT [0<--906]
OPEN
Thanks, we appreciate the kudos!
Post #22 of 22. Posted by Gerard Vroomen on 22-Aug-2016 18:56:24 GMT [906<--907]
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