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


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.


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.

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.


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.



Frame sizes:S, M, L
Frame-only weight (+/- 3%): Size S: 848g
Size M: 869g
Size L: 885g
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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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 44. Posted by Putra on 03-May-2016 12:19:37 GMT [0<--639]
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 44. Posted by Gerard Vroomen on 10-May-2016 14:36:28 GMT [639<--653]
How does the chainstay length affect the handling? For me 440 mm seems a bit too long.
Post #2 of 44. Posted by on 09-May-2016 09:04:41 GMT [0<--650]
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 44. Posted by Gerard Vroomen on 10-May-2016 14:45:46 GMT [650<--656]
will it work with 120 mm fork?
Post #5 of 44. Posted by on 17-May-2016 11:45:39 GMT [0<--680]
Yes it will.
Post #6 of 44. Posted by Gerard Vroomen on 17-May-2016 15:58:32 GMT [680<--681]
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


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

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?

Post #12 of 44. Posted by on 31-Jul-2016 17:03:51 GMT [0<--830]
Post #13 of 44. Posted by Gerard Vroomen on 01-Aug-2016 23:03:34 GMT [830<--833]
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 44. Posted by on 03-Aug-2016 22:26:54 GMT [0<--843]
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 44. Posted by Gerard Vroomen on 07-Aug-2016 10:49:55 GMT [843<--851]
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 44. Posted by on 14-Aug-2016 15:08:58 GMT [0<--869]
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 44. Posted by Gerard Vroomen on 17-Aug-2016 00:00:13 GMT [869<--872]
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 44. Posted by on 22-Aug-2016 16:18:27 GMT [0<--906]
Thanks, we appreciate the kudos!
Post #22 of 44. Posted by Gerard Vroomen on 22-Aug-2016 18:56:24 GMT [906<--907]
The head tube angle is very steep. I ride a Scott Scale SL 900 and have gone over the handlebars several time especially on slow steep rocky downhills when the front wheel "hangs up" behind a rock. Doing the same downhill using a bike with slacker head angles does not send me over the handle bars easily. Is the steepness of the head tube angle not a concern with regards to especially the slow down hilling ability?
Post #23 of 44. Posted by on 31-Aug-2016 11:55:58 GMT [0<--926]
Not for us or any of our customers. What you are referring to is not a head-angle issue per se as much as it is related to front-center and the location of your center of gravity. Now, front-center can be related to the head angle but it doesn't have to be. For example our geometry is designed around a short stem, which increases the front-center without needing to slacken the head tube (which has all these other drawbacks).
Post #24 of 44. Posted by Gerard Vroomen on 31-Aug-2016 16:11:00 GMT [926<--927]
will this frame fit 29x3.0 tires...specifically the maxxis chronicle
Post #25 of 44. Posted by on 11-Sep-2016 19:31:30 GMT [0<--964]
No, that would completely mess up the geometry (and require a much more stretched out frame, which in turn would mean it wouldn't have the perfect XC behaviour anymore. So you can fit 27.5x3.0" tires (or 29x2.4") as those have the same overall diameter and thus the same handling characteristics.
Post #26 of 44. Posted by Gerard Vroomen on 13-Sep-2016 08:58:48 GMT [964<--965]
Is it possible to have two different wheel sets -- for example, a 29x2.0 xc race set and a 27.5x3.0 trail set -- and interchange them with relative ease? I guess I'd have to have identical hubs so rotors line up fairly well, with maybe some minor caliper adjustment? That would let me have a one-bike quiver! Possible?
Post #27 of 44. Posted by on 15-Sep-2016 22:33:36 GMT [0<--967]
Absolutely, that's what most of us do. Normally no caliper adjustment is needed, especially as you say if you have identical hubs and rotors.
Post #28 of 44. Posted by Gerard Vroomen on 20-Sep-2016 12:13:20 GMT [967<--972]
Thanks Gerard! I bought the 0-1.0 in January (Probike Supply) and while I'll probably buy the One+ frame soon, now I'm curious what the the different combinations are on my 0-1.0? I have 29x2.0 on there now for racing, but do you happen to know the max tire size for 29, and also if I put a 27.5 on, what do you think would fit? I'm guessing not much option since it's not a boost frame.
Post #29 of 44. Posted by Matt May on 25-Sep-2016 17:34:20 GMT [972<--991]
Hi Matt, you can't rally fit a 27.5 in the O-1.0, there is not the width to put a tire big enough to create the outside diameter that's close to the 29", if that makes sense. Basically in 29" and 27.5" you can faith same width tire in the frame, around 2.3-2.4" depending on the brand and the clearance you can tolerate, so then the 27.5" wheel is simply too small. It's not so easy to fit the 27.5x3" tires into a frame like this, that's why we had to work a long time on the ONE+.
Post #30 of 44. Posted by Gerard Vroomen on 28-Sep-2016 19:36:38 GMT [991<--1006]
ONE+ here in come! Already have someone interested in buying my 0-1.0 frame so all is good.
Post #31 of 44. Posted by Matt on 29-Sep-2016 11:44:47 GMT [1006<--1009]
Hi Gerard, I've been riding/racing O-1.0 for about three years. I love it. Especially impressed with how durable it's been, (most of my frames break after a couple of season).
Thinking about one+ . If you want to interchange a set of 29er race wheels and some fun 27.5 3" tires, are you limited to a lefty fork ? What other options can you recommend?
Post #32 of 44. Posted by Al on 08-Oct-2016 01:42:40 GMT [1009<--1022]
Hi Al, not at all. There are many forks that will work. In fact the Lefty officially doesn't work, except that it does. But basically any fork that will work for 27.5x3" will also work for the 29er tires. That includes some regular forks and many Boost fork. I'm actually gathering fork info right now for a new blog in the next few weeks. But the good news is, there are more and more forks appearing that will work, as the Boost standard becomes the standard of choice.
Post #33 of 44. Posted by Gerard Vroomen on 09-Oct-2016 14:51:29 GMT [1022<--1025]
Andy and Gerard, how important is the fork offset? I have a SID, and most SIDs sold have 51mm offset.
Post #34 of 44. Posted by Matt on 14-Oct-2016 23:00:19 GMT [0<--1052]
Hi Matt, all SIDs also come in a 44-46mm offset, so that is the best version to get.
Post #36 of 44. Posted by Gerard Vroomen on 15-Oct-2016 10:22:32 GMT [1052<--1055]
Gerald, do you have any opinion on ovalized rings, such as rotor?
Post #35 of 44. Posted by Nick on 15-Oct-2016 00:24:36 GMT [0<--1053]
Not really.
Post #37 of 44. Posted by Gerard Vroomen on 15-Oct-2016 10:22:47 GMT [1053<--1056]
Andy and Gerard,
I took delivery of my ONE+ yesterday from Pro Bike Supply. You should be aware that what is in the box is NOT what you state above. When I opened the box, two things were missing: 1. there was only ONE derailleur hanger, not two. 2. there was no star nut, bolt or top cap for the headset. You need to be aware of this...very disappointing since it is an expensive frame and "headset" generally means "complete headset."
Post #38 of 44. Posted by Matt May on 16-Oct-2016 19:09:39 GMT [0<--1057]
Hi Matt, occasionally it happens that the second hanger is missed, though that's become quite rare. As for the star nut, the UP and ONE+ share the same headset except for the star nut (which is already pre-installed for the UP in a sleeve for its fork) so it seems you got one of those headsets. As you probably expected, Pro Bike Supply will take care of you for these two items.
Post #39 of 44. Posted by Gerard Vroomen on 17-Oct-2016 20:47:51 GMT [1057<--1063]
hello. there is a relatively big gap between the m and l model regarding the seattube length. i would need the m frame but having very long legs (89 inseam, 1.80 high, short arms) the seatpost length (ca. 30 cm!) would look too absurd. will there come any size in between or can you offer something with ca. 47-48 mm seattube? thanks from germany
Post #40 of 44. Posted by heiko gastaldello on 20-Oct-2016 09:12:32 GMT [0<--1072]
Hi Heiko, why would the seatpost length look absurd at 30cm? That's pretty normal, you take a standard mountainbike seatpost at 42cm, 12cm inside the seat tube and 30cm outside of it. If you have any less sticking out of it, you'd become tempted to shorten the post. There definitely won't be a size in-between given that the step from M to L seems to work very well.
Post #41 of 44. Posted by Gerard Vroomen on 20-Oct-2016 10:32:02 GMT [1072<--1073]
Do you have a size chart, also where can I buy a frameset?
Post #42 of 44. Posted by Brian Bigeliw on 20-Oct-2016 21:41:39 GMT [0<--1077]
Hi there Brian, Yes, for the geo chart, just scroll up a bit. Our dealer list is also on the site, at the top right portion of the menu. Please let me know if you have any problems finding them.
Post #43 of 44. Posted by Gerard Vroomen on 20-Oct-2016 23:34:17 GMT [1077<--1078]
I will be part of Cape a EPIC 2017, the goal it is very simple , to be finisher and enjoy each day. I would like to up grade my unlimited version with more than 6,000 km . New SRAM eagle, what model do you suggest in order to have pleasent uphill and fast performance in the plane areas. Please let me keep simply my new aventure :)
Post #44 of 44. Posted by Guille on 25-Oct-2016 07:57:57 GMT [0<--1109]
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