FAT Unicycle sizes

Hello everyone.

I wanted to ask everyone what your experiences are with FAT sizes other than 26".

I’m currently planning my new financial year. One idea is to also make FAT forks in 24" and 20" for 4" tires.

New FAT forks in 26" made of aluminum will come anyway.

I’ve been riding my 26" fat unicycle for a while now and have been trying out a lot. A 26" fat unicycle with 4.0 tires has the same diameter as a 27.5" unicycle with 3.0 tires.

24" Fat with 4.0 tires would then have the circumference of a 26x 2.0 tire, if my calculation is correct. They would then probably be a little more maneuverable on trails

Are there any drivers among you who use 24x 4.0 or 20x 4.0 tires? What are your experiences?

Does it make sense to offer such unicycles? From my point of view, it can’t hurt if the diversity becomes greater.

What do you think ?

I am a fan of the 24” fat tire setup. I originally installed a Specialized Big Roller 24x2.8 on a Surly Large Marge rim (actual tire width 3”), and loved it for Muni, and for parades (with extra air in the tire to lessen the contact patch on concrete).

Recently, I installed a Vee Speedster 24x3.5” tire. While the tire width only increased .35”, the diameter of the tire increased quite a bit. The tire diameter is now 26.5”. The initial ride was yesterday, and the tire handles amazingly well on concrete.

I have not tried this tire on dirt yet, but I look forward to trying it on trails with roots and rocks soon.

I was hesitant to swap the tires because I enjoyed the Big Roller so much, but was happy to find that I love the 24” fat experience.

Specialized Big Roller 24x2.8

Vee Tire Speedster 24x3.5

This is how the tire compares to (left to right) Schwalbe Big Apple 28x2.35, Maxxis Hookworm 27.5x2.5, Maxxis Holy Roller 26x2.4, Vee Tire Speedster 24x3.5

1 Like

I have been happy with the Specialized 24x4.0 tire (Ground Control?) on my Conundrum fat uni because of the structure and tread. I will try to make a pic of it as I don’t remember if I shared it in the fat uni pics thread.

The only downside for this tire is that you can only buy it from specialized’s website (a shame for such a nice tire).

@www.einradshop.ch : when I saw the thread title, the first thing that came to mind was 27.5x4.5 that seems to be the new trend.

1 Like

Thank you for your answers. True, there are also 27.5" fats, e.g. Maxxis Minion. But this size is already covered by the “normal” fat fork anyway. The feedback from customers wasn’t that good either. One customer had a fatty with Surly Nate 26x 3.8 and Maxxis Minion 27.5x 3.8 and said that it was much better to drive with the Nate. I wanted to clarify whether it made sense to build smaller fat forks. It’s always a big investment, especially for a small dealer like that It’s me. I’ll think about it and test tires to see if there’s anything good. I can’t find the Specialiced tire you mentioned on the website, actually nothing that looks like “Fat”. Maybe it’s been discontinued canceled or it is not available in Europe. I ordered CST tires to test the driving characteristics.

are you happy with the Speedster? I drove the 26x 3.5 a few years ago when I also had VeeTires in the shop. It was nice to drive in a straight line, but corners and self-steering on sideways slopes were terrible.

I run a 4 inch tyre on my 24 in the winter when there is a lot of snow about. It is a Vee Mission Command.

On the one hand it is great. I can run low pressure and it floats over most things , whicle the uni still remains relatively small and compact. So it is great for bringing with me when a larger uni might take up too much space. On the other hand I do fight with this tyre a lot. It self steers. I do not know if this is due to the width (I never used a 4 inch tyre on any other uni) or because of my specific setup. Despite the effort to control it, it is a net positive when the conditions warrant it. Still… I should probably try another tyre and see if that improves things. All in all though, I am glad I have it.

As for the fat 20, I have never tried one but am curious. Both UDC/Nimbus and M4O/URC make them so clearly there are those that see some value in such setups. At the very least, it would make for a fun muni for young adults and kids. Though I am sure it would be great fun as an adult as well. :wink:

1 Like

Here is a previous iteration of my 24x4 (before I switched over to ISIS and added a brake). This is just to show a comparison alongside a 26 running a plus size (2.35 inch) tyre. As you can see they are very similar in diameter at least visually. I never bothered to accurately measure.

1 Like

The fact is that wider tires often have more autosteer. However, there are big differences from manufacturer to manufacturer. That’s why it’s really worth trying out different models. With the 26" tires I find the Kenda Juggernaut Pro to be the best to steer. With 24" the selection is smaller. I’m looking forward to the test tire from CST.

1 Like

If you find a nice fat 24, please let me know :wink:

it doesn’t seem easy. The Chaoyang Big Daddy is good as a 3.0 tire, and as a 4.0 tire it also has a lot of autosteer. The CST BFT 26x 4.0 (also available as 24x 4.0) has just arrived. I have now mounted it on the Fatty. It’s not perfect, I can’t make fast, tight turns (okay, the only one that works is the Kenda Juggernaut). I’ll test it out in the next few days, but it doesn’t come close to a Surly Nate 3.8. The BFT also seems to have quite a bit of autosteer. But I’ll drive it for a while to really judge it.
We currently still have soft ground in the forest after the snow and frost. With my Surly 4" Fat tire I roll on soft surfaces worlds better than with a 3" tire

1 Like

Yes I suspect this is potentially the biggest problem with offering fat unis in the 24 size. There are tyres but as you say not many and it might be that none of them are great for unicycling.

The Specialiced Ground Control is supposed to be good, but I can’t find it on the website, so it’s probably no longer manufactured. There is no importer in Switzerland that offers a 24x 4.0 tire. Since I only sell small quantities, I would of course prefer to order such tires in small quantities.
Now to the CST BFT 26x 4.0. It doesn’t drive as bad as I thought. It does have a lot of self-steering, but not so bad that you can’t drive. A Schwalbe Jumbo Jim is worse. I ordered the tire from Aliexpress to test. What strikes me is that it is significantly heavier (almost 1600g) than declared on the CST website (1280g). I wonder if there are different qualities (OEM vs. official).
But I will also test the chaoyang big daddy again, because it also has 20x4.0 and 24x 4.0. Kenda also has a 24x 2.40
In 2021 I defined a new track width of 120mm instead of 100mm to build forks for my 4" Fattys. 2cm more internal width for forks is good. My idea is to make all MUni forks like this. 3" or 3.25" fit in anyway It would mean more flexibility with the tires and I wouldn’t have to have all the forks twice.

1 Like

I am still very early on in my test of the Speedster, but the initial results have been great!

I currently have the tire aired up to 17psi. At this pressure, the tire still feels cushiony, and feels like the most round tire I’ve ever ridden. Compared to my 20"x4" Monster unicycles with Boomerang tires, the Speedster rides as if it is half the weight, and I don’t feel like I am muscle-ing it around. I also don’t feel like it is dictating the ride, like I sometimes feel with the Boomerang.

I have not had a chance to get it on dirt yet, but the rides on pavement have filled me with optimism.

One thing to keep in mind, is that I am riding the 3.5" Speedster. I believe I read reviews of the 24x4" Speedster that mentioned camber sensitivity, which is why I chose to install the 3.5" version.

1 Like

It the most likely explanation :frowning: Even back when I bought it, you could only order it from specialized.com (it wasn’t a good sign in retrospect). And it was during the boom of fat bikes for kids. Seems like they decided the market was not profitable enough…

Fortunately there are still a few manufacturers still producing fat tires in 24" but none of the audience favorites. As for sizes, my 2 cents are that 24 fat is a thing as an extension of the 3.0 of yore but there was never a 3.0 trend with 20 meaning that it may remain a novelty.
And for the hub pitch, I am all for more choice of manufacturers but was surprised by the choice of 120 instead of 125 (like Nimbus) as the compatibility would have opened a bigger market (especially for all the nimbus aluminum hubs failing and making their riders long for a steel replacement).

1 Like

Because of the hub width, it was just a logical thought on my part as to what I needed for 4" tires. Sure, I could also have made some curved forks for 100mm hubs, but I don’t believe in that. I didn’t want to copy anything. I was fluctuating between 120mm and 130mm, it should be a number that is divisible by 2 for the technical drawings. I couldn’t have given a guarantee of 100% compatibility with other brands with 125mm. For me, 120mm should become the new standard for the MUnis. As long as you If you don’t do unicycle racing, these 20mm more only bring advantages because you can install a larger range of tires. With 20" and 24" the selection of tires up to 3" is very small, but there are also 4" tires. The same applies for 26", where there are very few tires around 3" left, but some fat tires 26". Well, that’s all still a thing of the future. At the moment I “only” have a CrMo fork in 120mm. First the aluminum sample forks must be tested and the technical drawings may need to be corrected. That means it will take a year until a series is available.

Please forward any complaints about poor English directly to Google :slight_smile:


How about 62.5mm? That’s 125 / 2?

The bike industry has gone full stupid with their hub width. It has gotten super complicated with all the different sizes. It would be better for the you and the riders if your frame were 125 as well, then your parts would be compatible with other brands as well.

I dont ride a fat tire on anything smaller than a 26’’ so I can’t comment on the original question of the post. I like smaller tires that are more responsive, on which 100mm hubs make sens. I wouldn’t want to ride a 120 or 125 with a smaller tire.


I think you should try this BFT 4". I’m liking it more and more. It doesn’t have a deep profile, but it’s open = good self-cleaning. I’m currently driving both the 27.5x 3.0 and the 26x 4.0. They don’t shine in any discipline, but they do their job. I drove yesterday on a path with an annoying side slope and muddy spots. I expected the tire to grease away, but it did its job well.

1 Like