Nimbus Hatchet - Which rim/tire size would you build?

According to

The Nimbus Hatchet builds on the amazing platform that the Oregon created, and moves it onto the next level. The frame comes with the brake installed on a new precision IS mount. The hose is also clipped in place with special red aluminium clips. The main challenge with “Fat-Uni’s” is the requirement for a super wide frame. This can make it uncomfortable to ride as it catches the riders’ legs. To resolve this the Nimbus Hatchet moves the frame behind the riders legs giving maximum clearance. This also means you can run some of the largest tires on the market, which includes the Snowshoe 5.05" tire.

This frame will hold a tire up to 26" x 5.05", 27.5" x 4", 29" x 3.0" and a 32" x 2.125"

My observation is that real world tire diameter and fitment varies by manufacturer and setup. Ideally I’d love to run one of the new 27.5x4.5 barbagazi/gnarwall tires from bontrager but I fear that they exceed the suggested tire specs by to significant of a margin.

If you are running a hatchet with an aftermarket tire setup, please post your setup, and any comments about fitment and ride quality are greatly appreciated. Pics too.

Keep in mind that just because you can run a 5" tire doesn’t mean your legs will clear it without getting used to it.

I haven’t ridden anything bigger than my nate on a 65mm rim, but I find that more than adequate for deep snow. . . if that can’t handle it, I wouldn’t be riding in it with a 5" tire I don’t think.

I believe there are some other reports from people who have ridden the 5" tires that reported that beyond a 4" you’re not getting much benefit, but you gain some weight. Maybe Saskatchewan can chime in on this one, he’s ridden a lot of sizes I think.

Tread pattern is crucial on a fat uni. The Nate works with pretty much no autosteer at a sufficiently high pressure, and has mild-moderate autosteer as you start dropping to snow pressures. Just bear that in mind as well. (my experiences are on a 65mm rim, this may change on a 80 or 100 because you get a more square tire profile.)

If I had a hatchet, I’d run it with that maxxis and 80mm rim it comes with. It looks like it fits the wheel well. The 4" Conundrum I run year round is perhaps more versatile when you hit hardpack, even if it’s a bit slower (due to more effort to push than anything else) than a 29x2.4.

Thanks for the reply juggleaddict, I realize that the stock maxiss tire more than adequate, as is the dirt wizard on the 29" version. Nimbus wouldn’t pair their new frame with a bad rim/tire combo, that just business. But, to me, the appeal of the frame is its versatility. I would like this thread to be a knowledge base for anyone looking to build a hatchet with an alternate setup. Hopefully it won’t turn into a list of reasons why they shouldn’t.

That being said, has anyone actually built one of these with one of the following:
Vee Tire Snowshoe 2XL 26 x 5.05
Vee Tire Apache Fatty Slick 26 x 4.5
Surly Lou 26 x 4.8
Panaracer Fat B Nimble 27.5 x 3.5
Bontrager Hodag 27.5 x 3.8

Currently mentioned or recommended:
Maxxis Minion FBR 26 x 4.8, 120 TPI (Stock Tire)
Terrene Wazia Tough 26 x 4.6 60/120 TPI (UDC)
Surly Nate 26 x 3.8, 120 TPI (juggleaddict)


Surly 29 x 3 Dirt Wizard 60 TPI (Stock Tire)

I grabbed whatever I could buy at half price in the sales, aiming to upgrade later if required.
The wheel was £40 hub / £40 rim / £35 tyre / £25 tube, tape, spokes = £140 total ($175)
Then I added the frame, saddle, post, clamp, 160mm cranks & Onza pedals
Jobs still to do are to weld the £25 handlebar brackets up, before fitting the £30 Shimano disc brake.

It works OK for £320 all in ($400).

After looking at the Hatchet for a long long time, I personally ended up buying the KH 29+ with the 29x3" Maxxis Minion DHR II last month, as I decided that for me the 3.0" was enough width.

I don’t know the tire myself, but concerning the 27.5x4.5 barbagazi/gnarwall tires, you just need to ty and find the width and true height measurements on a given rim width (I found similar stuff for lots of tires on the fat mountain bike forums). Also the bead-to-bead meaurement can help with estimates too if you don’t find the exact combo tire/rim you want to try.

My gut feeling says that the 4.5 width should fit and your only real limitation should be the frame height. For example the Surly Lou 26x4.8 has a total height/diameter of 778mm and bead-to-bead of 260mm and fits for sure. Sorry no links, but I am pretty sure the Lou 4.8 fits as it was on my list for my possible setup for the Hatchet. Oh, if I remember right, I think the Bud 4.8 is a touch bigger and is fitting in the Oregon (from post here).

So check if you can find the bead-to-bead, effective diameter/height and width numbers and see what the widest rim that will fit.

I measured my 29+ Maxxis DHR II 3.0 at 180mm bead-to-bead and 764mm height/diameter on the KH Freeride 47mm rim (don’t have my width measurement here but I think it was right under 3.0") and I have ample vertical and horizontal room in the KH frame and the Hatchet it much wider.

According to measurements from the Internet, the 29+ Dirt Wizzard is slightly smaller than the DHR II at 761mm height and a bit less than 3.0" width on the 47mm KH).

Hi Unisomniac,

do not let the list of tires from the description throw you off. They are here just for information and usually only account for the tire sizes available at the time it is written and not the max size.

Second, as mentioned before, it is all about the height (mostly) and to my surprise when I measured, 26x5 is bigger (in diameter) than 29x3.0.

So in an Oregon/Hatchet, the height will be the limit and you should find the diameter of the 27.5 rim + tire combo you want.

For the 26" fat tire and the Oregon (ancestor of the Hatchet), you will find plenty of working setup with the Surly Bud, Surly Lou, Schwalbe Jumbo Jim and there is one SnowShoe 2XL. There is a dedicated Fat tires thread to discuss and share reviews.

The most standard threads are the Monster Uni, Current projects and Latest Ride. However, like with the 2XL, they can be discussed separately (and only the search function will be able to help you find them).

I can’t wait to see the pics and feedback on your 27.5 fat setup :wink:

Thanks for the reply Siddhartha, tons of info in those links :).

So assuming I can actually fit the Barbegazi 27.5x4.5 on the hatchet frame (actually looking like a possibility). The challenge then becomes finding either an off the shelf or sanely priced custom 36H 27.5" rim wide enough to run tubeless :-/

Any Ideas?

32 hole Nimbus hub

Don’t know anything about 27.5 rims.

But another option should be a 32 hole rim, as UDC has a few 32 hole hubs. About 2 months ago they were available in the US and after my inquiring UDC-Germany (Roland) had 2 or 3 shipped to Germany. Not sure where you’re located, but I think in USA or Europe there should still be some available.

At least that should allow you to simply search for the best rim and then choose the hub accordingly.

My setup on the Hatchet: The stock Rim Large Marge 65 mm is equipped with 45nrth Dillinger 5 studded tire (4.8 ") for icy conditions. Almost no autosteering!
Have built a fatter wheel as well: Surly Clown shoe 100 mm with Surly Lou 4.8 tire. Surprisingly little autosteering, but requires “a firm hand” (leg?) sometimes to handle.

Because it is so wide, I have to remove the brake when switching wheels, but that is not a big issue, really.

If I could make this work…

Can anyone with more experience in building custom unis offer any information about the compatibility of the following components?

Hatchet frame:

Nimbus 32h wide hub:

Nextie Wild Dragon Rim:

Bontrager 27.5x4.5 Barbegazi Tire:

disclaimer links are provide to help answer my question. I do not endorse, receive compensation for, or promote any of the products or companies listed. If this is against the rules, I will kindly remove them.

I will need to measure the clearance on my 26x 4.0 tyre to the crown of the frame for you (probably tomorrow morning).
The larger diameter 27.5 rim, plus another 1/2 inch on the tyre is going to make it a very tight fit for height clearance on the frame.

Reverse engineering the other tyre sizes suggests that 4-inch might be the maximum 27.5 tyre size.
Someone with a 5.05 inch VeeTyre Snowshow 2XL will be able to make a better guess on whether you will have the extra 0.4-inch clearance required.
26x 5.05 = 36.1 inch diameter
27.5 x 4.5 = 36.5 inch diameter
27.5 x 4.0 = 35.5 inch diameter
29x 3.0 = 35 inch diameter
32x 2.125 = 34.25 inch diameter

27.5x4.5 is actually in the vicinity of 31" diameter. It is slightly larger than a 26x4.8 Surly Bud as the Bud just clears a Bluto fork, but the 27.5 Barbegazi rubs.

The whole 27.5 fat is pretty much a marketing gimmick as it is only slightly larger (.75" or so diameter/ .375" radius) than a 26" fat tire. It is nowhere near as big as the 1.5" size difference suggests. In fact the 27.5x4.0 Hodag is so undersized it is smaller in diameter than some 26x4.0 tires.

Personally I’d go with 26" fat as it will allow you to run a lot more different tires and you aren’t stuck with a few options (three Bontrager and one Maxxis) that may or may not work well for uni. Unicycle handling is way too tire dependent especially with fat tires to limit yourself to a few choices.

Ooops, I forgot to subtract the standard 2.0-inch tyre size.

So a 27.5 wheel (outside diameter with a 2.0 tyre) will have a rim ISO size of 548 for the rim and tyre bead diameter, according to the UDC (UK) website:
27.5 inch = 548mm, which is 21.9 inch, plus 4.5 tyre (x2) = 31 inch overall diameter.
26 inch = 559mm, which is slightly bigger at 22.3 inch plus 5.05 tyre (x2) = 32.4 inch diameter.
Now I am really confused.

On the plus side - the 27.5 x 4.5 should fit, with it being a smaller rim diameter (if the UDC-UK figures are correct), and a smaller outside diameter overall.

Lets start clean:

27.5 or “650b” has a BCD of 584mm or 23.0"
26" wheel have a BCD of 559mm or 22.0"

27.5 rims are almost exactly 1" larger than 26" rims.

Why we call them 27.5? Here is what Sheldon Brown has to say:

"As if bicycle tire sizing wasn’t already confusing enough, wrong-headed marketeers have recently tried to popularize a fourth designation for the 584 mm tire size!

They are trying to get people to call it “27 five,” as if it were halfway between the MTB “26-inch” and “29-inch” sizes. (Get it? “five” actually is supposed to mean “point five.”) Actually, this size is closer to the “26-inch” (ISO 559 mm) size than the “29er” (ISO 622mm) size, and even smaller than the “27-inch” (630mm ISO) size found on older road bicycles. I strongly urge readers to resist the foolish jargon, and to use either the traditional “650B” designation, or, better yet, the internationally-standardized 584 mm designation. "

EDIT: a little Googlefoo brought up this:
[on a 65mm Nextie rim] diameter at 20psi is more or less 770mm and the width of the casing is 115mm, with a few extra mm of knob.

770mm = 30.3" so you should be OK in the Hatchet frame.

The UDC-UK website has the numbers mixed up at 548mm - hence the confusion

The hatchet frame has 40mm clearance between the Kenda Juggernaught 26x 4.0 tyre (98-559), to the top of the frame.
35mm of that extra height should be usable.

Across the top of the tyre, there is 135mm width (=5.4-inches so plenty of frame width), increasing to to the widest point a little lower down, appx 6-inches wide at 150mm.

So from what I’ve gathered, 27.5x4.5 Barbegazi fitment on the hatchet frame shouldn’t be an issue.
(Thanks for crunching the numbers reeny/saskatchewanian/paochow)

I really would prefer the widest rim on the market.
27.5" x85mm (wild dragon ii) is listed on nextie but under specifications, it’s listed as a 26 :confused:
27.5" x 65mm (black eagle ii) is listed as 27.5/650b compatible.

Does anyone know of any other options (80mm-100 mm 27.5 rims are probably a year or two out of the mainstream market from what I’ve gathered)

My other concern is the strength/durability of a 32h carbon rim in a muni application. Nextie has an option for the larger atomlab torque nipples. Is that something I should consider? The last thing I need is having my new 1000$+ uni grenading itself after its first UPD.

As for the argument that there are more options if I go the standard 26" fatty route. Yes, there are, but if I’m going custom uni route, why not be the one of the first guys out there with a 27.5 fatty? After all, none of us unicycle to blend in.

That being said, I’m just trying to do my homework first.
You can’t innovate if you are uninformed.

DHR 29x3.0 Review

If anyone’s interested, I Posted a quick review of the Maxxis Minion DHR II 29x3.0 tire for sand riding with a Nimbus Oracle here:

I have the 29x3 on my frame now and a 26x5 for winter season. love both

crazyunicyclerNJ (or others):
Curious how you would compare the 26x5 to the 29x3. I’m trying to use this tire for paddling through deep sand. The 29x3 does well if I can build a bit of momentum, but if the sand is really deep or churned up it finally ends up digging in and stopping me.

Does the 26.5 float way better than the 29x3? Any other differences? Any thoughts on a 26x4?


I actually prefer the 29 where I ride as I like the larger size. I ride a lot of technical trails, the 26x5 is good on it and cushions a lot more. i had more difficulty with larger obstacles likely because I had a lower tire pressure and the tire deformed more to go over it than the 29x3.

What I did notice also was my 29x2.25 vs my 29x3 (completely different unis) is that the 29x3 was more forgiving when you didnt get your line right in the technical part, the 26x5 even moreso sometimes, but was easier to get stuck between 2 rocks