20" Mini Hatchet

Ok, how the hell did I miss this? Have we discussed it already somewhere?

As far as I can tell this is the the old 20" Nimbus Purple monster unicycle but now with a cute :heart_eyes:, downsized Hatchet-style frame. That does however mean it has cotterless cranks rather than ISIS and no brakes nor a straightforward way to add them (though brakes on a 20", even with a fat tyre like this, is perhaps an overkill anyway :person_shrugging:t3:).

Despite being relatively low spec, that Hatchet style (in mini form) still looks great and since it is pretty cheap, I am sort of tempted anyway. I had already looked at the 20" monster before as a fun little thing.

I see that it is not avilable until October on UDC UK

But the US website already has it. Indeed one of the guys I follow on Strava (Paolo Unitoonist) is already riding around on one (which is how I found out about it [from his pictures])

Edit: Image stolen from Josh’s Instagram account, showing the new 20" lying in front of the 26"


Yeah I saw this the other day. Tempting! I do wish the hub was ISIS. Looks super fun.

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You could buy an ISIS hub and rebuild the wheel but your problem would be getting ISIS bearings in a frame designed to house 40mm bearings. You used to be able to find stuff like this but you might struggle to these days.


Seems really odd to have gone to the bother of making this but make the frame suit only square tapered bearings.

I’d be more inclined to try this if it were tough and like a mini fat muni/trials ride.

Guess it’s about keeping costs lower, but still.

Odd, but cool all the same!

Also interesting this frame is steel but designed visually like the aluminium Hatchet.


Yeah I think it is a relatively cheap thing for fun but without high expectations. I imagine also there is an element of buying this for kids who can unicycle and want to have something that looks like the “adult version”. That said the nimbus cotterless hubs can take a little pounding and that fat tyre will obviously absorb a lot of the impact that would get transfered more harshly to the crank interface on a machine with a smaller tyre. It might hold out better than expected.

So as I said, still sort of tempting as something to play around with. I did almost buy the monster at one stage despite similar limitations and this basically the same but a little more fun looking.


A couple of years back when those 40mm ISIS compatible bearings were still for sale, I considered buying them. Not because I needed them at the time (I owned nothing I would use them on) but more as a, “you never know” :thinking: kind of purchase. I kind of wish I did now. :wink:


So it is a longtime to convince @rogeratunicycledotcom to put isis hubs and cranks on it.

ps: saw this about a week ago on @JoshBuilt instagram site:



Yeah and immediately rebuilding things just kinda counteracts the low initial cost. It’s neat but I don’t think I will spring for it. Bit of a tease lol.

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Yeah but that would require a new frame to house 42mm bearings (since this frame can only accomodate 40mm bearings), or some special bearings like the Kris Holm ones I linked above that can be used on ISIS hubs but are only 40mm. So basically this is a non trivial change.

If there is an update to this model in the future I would have the frame accept 42mm bearings and if UDC wants to keep the base product as square taper, then sell it with shims (40 → 42mm) already installed. Mad4One does this with their low end square taper unis. Thus it is easier to upgrade to ISIS, since you can always shim up in bearing width but going down is non-trivial.

If they wanted to make it really upgradable, a disc tab would also be nice. Although… 20"… maybe that would be a total overkill in any case. :person_shrugging: You would need somewhere really steep and/or crazy short cranks to justify it I suppose. At that point maybe you are just making this into something it is not.


This has clearly been built for a child as an introduction to off road unicycling hence the square tapers which are fine for a lighter weight child. I don’t think they had in mind a 175 lb adult doing massive drops with it.


The more I look at this and think about the limited spec, the more convinced I am that this is primarily aimed at the kids market. For kids who will not push it as hard as an adult and are much lighter (plus the fat tyre) this is likely “strong enough”. Plus you get the lower price. That is not to say an adult could not use it and have some fun, no doubt they can (within limits and expectations) but I think they are a secondary consideration.

EDIT: @Bug72 beat me too it! :wink:

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Great minds think alike.


I`m a kid, just the age is different. :grinning:


Thanks, I stole one of his images (the side-by-side view) and added it to the first post (above). I figure he probably will not mind as it is effectively promotional anyway. :person_shrugging:

Seems you can get 22x40x12mm bearing if you really want to, making an ISIS rebuild possible.
I assume these will fit:


Interesting. That looks like it might have potential

But… the more I think about this the more I suspect that rather than trying to make this into something it is not, it should just be accepted for what it is. For kids it will be fine and for adults you can do a little “light” play… and it is fairly cheap.

If you really wanted a “mini fat” uni that you could abuse out of the box, it would probably make more sense just to buy something like this:


Indeed the unique frame design on the Hatchet matters less on this little Hatchet because the wheel is so much smaller, so you probably won’t hit your knees much anyway, especially as 4" is the max width unlike on the big Hatchet which goes even wider.


So one think about the M4O fat tire unis, they have narrower rims. I got the 27.5" techno fat and it was a 3.8" tire mounted but was only 3.3" wide.

Not a huge deal and it did ride in snow quite well but something to be aware of if you want the full size of the fat tire. Looking at the frame sizes too you could probably fit it into a regular Nimbus frame.

That same 27.5" fat wheel fit my 29" Nimbus frame perfectly and it’s made me consider building a fat tire 20" in my 24" frame but I need to test how my 24" x 2.8" does in deep snow first.

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Fair point about the rim width but even if you did want to get the best (and greatest width) out of the available 4" tyres, rebuilding the M4O/URC fat 20" wheelset with a wider rim would still be less work than what you would need to do to the 20" Hatchet to bring it to peak performance, since the Hatchet would need a rebuild anyway to gain an ISIS hub, plus you need to get hold of usual/uncommon/untested bearings to fit the frame and you are still left without the possiblity of a brake. Oh … and the frame on the Hatchet is unlikely to be as strong due to the unusual design.

So starting with the M4O/URC fat 20" it is less work to get things “perfect” and if you can accept the smaller rim… you don’t have to do anything at all.

I still think the baby Hatchet has its place/niche and there is some overlap with the 20" M4O/URC mini fatty but they are also pitching/optimised to slightly different groups.

If you are buying for a kid, buying for yourself but know that you are unlikely to push too hard, love the Hatchet look or just don’t have a lot of money, the Hatchet could still make the most sense. If you have the funds and care more about out of the box capabilities than “that look” the 20" M4O/URC fatty is probably the better option.

An extra thought (even though I have written far too much already). If someone buys one of these specifically to mess around in the snow, that will also be a lot more forgiving on the crank interface than hoping on hard tarmac, concrete, etc. with a skinny tyre. So again I speculate that maybe it will take more abuse than one might assume depending on how and where you use it.

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