is it worth it getting a 24"?

Unicycles and Equipment
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2B.2 Unicycles

Only standard unicycles may be used. Riders may use different unicycles for different racing events, as long as all comply with the rules for events in which they are entered.

For events divided by wheel size, there is a maximum allowable tire diameter and minimum crank arm length for each category:

Unicycle Class Max Diameter Min Crank Length Transmission
16 Class 418mm 89mm standard
20 Class 518mm 100mm standard
24 Class 618mm 125mm standard
29 Class 778mm No limit standard
Unlimited Class No limit No limit unlimited

For any tire in question, its outside diameter must be accurately measured.

Crank arm length is measured from the center of the wheel axle to the center of the pedal axle. Longer sizes may be used.

In all track racing events on standard unicycles, shoes must not be fixed to the pedals in any way (no click-in pedals, toe clips, tape, magnets or similar).

Question: How is “standard unicycle” defined?

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A unicycle in its simple original form: a wheel, a pair of pedals and a saddle. So no brakes, no handle bar, no gear, nothing extra.

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Wrong. Handlebars, and brakes are allowed on a standard unicycle. For all practical purposes, a standard unicycle has no schlumpf, isn’t a giraffe, Hunirex or Freewheel.

IUF Rulebook:

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91

What about the restriction on the width of the wheel. I was told that a muni 24 has too wide a tire, but I havent found the permitted IUF tire widths.

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No width restriction. It is because a muni size tyre on a 24 inch rim will have too big a diameter to comply.

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BTW Here is a related thread discussing why standard 24 wheel sizes are different for basketball from track unicycles.

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The word “standard” can have different meanings or translations. In a strict sense, standard could mean IUF has designed a racing unicycle and that every racing unicycle must conform to those IUF standard racing specifications or that each and every racing unicycle must be and look exactly the same. Or in a more practical sense, it could mean no alteration or modification of a unicycle manufacturer’s standard design. Or it could simply mean a unicycle must have one wheel, one seat and one set of cranks PROVIDED the wheel is not too big in diameter and the cranks are not too short, that modifications within IUF limits are allowed.

It is better to first know what “standard” means before making an expensive long distance trip to somewhere to only then discover that your unicycle does not have standard specifications and so does not qualify to be raced.

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That’s why the IUF has a rulebook, and there is a section:

Defining everything from “Age” over “Freewheel” and “Helmet” to “Unicycle, Standard”

See my last post in this thread for the exact definition by the IUF :roll_eyes: It’s pretty clearly defined.

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Here is the IUF Rulebook Committee 2018 Definition of Unicycle, Standard

Yet current definitions are still controversial and remain under discussion.

And I thought I had asked a simple question!

The term “standard unicycle” has two different meanings:

  1. The official meaning in 1D.1, which I quote in full:
    A Standard Unicycle has only one wheel. It is driven by crank arms directly attached to the wheel’s axle/hub, with no gearing or additional drive system. Pedals and cranks rotate to power the wheel. Is balanced and controlled by the rider only, with no additional support devices. Brakes and extended handles/handlebars are permitted. For some events, such as track racing, standard unicycles have restrictions on wheel size and/or crank arm length. Other events may specify other restrictions. When not noted otherwise, there are no size limitations.

  2. The colloquial meaning: any unicycle that permits the rider to start in most track races, and in the Standard Class (versus Unlimited Class) in Road Races.

(Strictly speaking, “Standard Class” is not a thing. But everyone uses that word.)

These two meanings are conflicting.

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Honestly, I don’t see much need to redesign the rules. Instead, we should be starting to always add the wheelsize to the “Standard” category when using it in events. If the usual “standard class” in a marathon would be called “standard 29” ", and there would be “standard 24” and “standard 29” in a 10 km race, it would be a bit more intuitive to people not familiar.

It’s honestly never really hard to find out which category your unicycle fits in races either way…

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“Standard” has become a lousy word for unicycles, because of too many uses and situations. The term “Standard Class” comes from a form of trick-riding competition that went away before the turn of the century. Later versions of that were Open-X and now X-Style. There was also the Standard Skill event, but the use of “Standard” in that referred to the standardized list of tricks that were available to use in your routine, each worth a fixed amount of points if you did them flawlessly.

The uni competition events that are the oldest tend to have the most detailed rules. Somebody always questions something that we all took for granted, but they didn’t know about it because they’re new to the sport and have no local unicyclists. So we keep getting more specific. The rules for newer events, like Flatland and platform jumps, are much more free, and much easier to work on!

Anyway, the IUF Rulebook Committee is currently voting on the final proposals for changes to the Rulebook for Unicon 20, 2020 in Grenobe, France. If that link above this thread works (not sure if you have to be a member), here’s the proposal for updated definitions for Unicycle, Regular Unicycle and Geared Unicycle. “Regular” basically replaces “Standard” in describing a unicycle that’s not a giraffe, more or less. 14 yes votes out of 23, nobody voted no or abstain yet.

Meanwhile, we also did some slight modifications to the wheel/crank definitions (for Track), to eliminate gray areas. Note that each size now has a minimum diameter. For most situations this isn’t needed; it’s only for events where smaller wheels are not allowed, like races over 20km.

I’m not sure if anything will change for the larger 24" size for Basketball and Hockey, since they now both share that definition, in two separate committees, which makes it harder to work on rule changes…

For both of those proposals, you can click the links at the bottoms of the pages to see the discussion that lead to the final proposals.

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Be cautious when using published tire width sizes to make assumptions about how accurate they aren’t. I think in the Road biking world, especially, these numbers are pretty accurate. But as tires get wider, they seem to be fairly fluid; some much more than others. While the BSD has to be accurate for a tire to fit the rim, width sizes are often “inflated” or otherwise inaccurate. The only way to really know is to try the tire on the rim in question and pump it up to “working” pressure. :frowning:

Speaking of BSD (bead seat diameter of a rim), we moved toward it for a while in unicycling, but then away again. The problem is, very few rims have the BSD marked on them. And more tires do, but not all. So there’s no way to confirm a legal-sized wheel at the track. So for now, we’re still using “the box”, a box that’s the specific size of maximum diameter. If your wheel fits in without rubbing, it’s legal. Some day we might return to BSD for wheel sizes in some events, but probably not Track, where the diameter is crucial.

Endlessly. :smiley: Hopefully the new definitions will stand the tests of time better…

As mentioned earlier, the actual side-to-side width is not restricted, but that number also approximates the “tallness” of a tire above the rim. A larger “width” makes for a larger diameter. Very few 24" tires are actually 24" in diameter! The old Schwinn tires were pretty close. The Miyata tires were smaller, and the old 3" Gazzalodi tire on my Wilder Muni was close to 26".

Basketball and Hockey use a less restrictive size for their 24" wheels, in order to accomodate the thicker tires that are common among players, and also common in the shrinking market for 24" tires. I recently had a bit of a panic when I couldn’t find ANY decent tires online to use as a replacement on my old Miyata. UDC only had a Muni tire, and Amazon had a slightly knobby one that probably wouldn’t roll as well. Everything else was too thick for the Track! If that trend continues, we may have to relax the maximum size for Track, but this will upset a lot of people because the older speed records would lose their status of currency. One by one they would fall. But isn’t that what records are supposed to do, be broken?

That would be the last thing unicyclists would want. Well, maybe Track racers; a pretty serious bunch. But the main restrictions for Track are maximum wheel diameter and minimum crank length. When we started adding races for other unicycle types (Muni and Road) we tried to avoid restrictions in order to let the riders, and the market, figure out what works best. So Muni and Road unicycles have less restrictions on them, whereas Track racing wants a more level playing field.

Absolutely! Especially if it’s far enough that you flew your unicycles there. That’s why we have to be very specific about those dimensions in the Rulebook. I’ve seen many people find out the hard way that their tires were a tiny bit too big (usually skinny 26ers), or a lot too big (the basketball-type tires).

I thend to agree with you. But people are nit-pickers. Also, sometimes we have to change things to fit the “now”, like a dwindling market for 24 x 1.75" tires, for example.

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Now nearly a year later I finally bought a 24" uni:

So many considerations. I really like the orange 24 muni they have, but to be real, I don’t ride wild muni tracks and would just take the 26" or 29" and if I do want to participate in the Dutch Championships again, I would at least need an additional wheel that complies to IUF rules. Though I very much like Nimbus, I think the QUAX has a good price. Not too cheap and not too expensive and a strong road tire, so I can also use it to learn some other techniques.

Now the only sizes I don’t have are the 27.5" and 43", though I don’t see the point in getting those. Also once tried sitting on a giraffe, but I thought it was too high. I would prolly break my feet when UPD-ing it. Now with ±11 unis I think the collection is complete for me :smiley:

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I recently bought a KH27.5 Muni so I didn’t have to swap wheels on my 29 between road and off-road.

The tyre on the 27.5 makes it almost the same diameter as the old 29. In fact my old KH29 fork only has five millimetres of extra clearance over the 27.5 fork.

I once thought nine unis was about right but now have nineteen wheels.:o Some share frames. Two wheels are UWs which are interesting to try but seemingly implausible. There is a Nimbus 5’ giraffe bought cheaply that I saved from neglect along with a little Club 20 thrown in.

My largest is a 36. I don’t have a 32, 16 or 12.

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why would you swap wheels for the 29" but not for the 27.5 inch? Isn’t that tire specific - a knobby tire or road tire.

Sometimes I wonder if I should have a 29" with road tire, but then I do have a 32" which has the road tire. Took it for a spin yesterday about 20km and somehow it gave me some problems mounting it. Probably because I had been riding smaller wheels in the last month. I like from the 32" that it is very agile. It turns easily on the asphalt and isn’t as slow and heavy as a 36".

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Now I leave the road wheel on the 29 and use the 27.5 with the big tyre for muni.

The main problem I had swapping wheels on the 29 was the different rim widths between the road wheel (older 42 mm? KH rim) and the wide muni rim (cutout 48 mm KH) meaning I had to refit the Maguras each time I swapped. More trouble than it was worth. (The extra 29 wheel and tyres came with my Triton 36/29.)

I got a really good deal on a virtually new KH27.5 not far away from home. The rim looks even wider but I have not actually measured it.

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Agreed! Got mine out last night after weeks of 29" with handlebars and big tire. The 32" is very agile, and feels very sturdy. I guess the 125mm hub helps making it very rigid.
Now I’m having second thought about putting the Schlumpf in there…

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Be my guest. I sold my schlumpf. It was not for me.

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My ride tonight was the first time on my 29 road wheel in a long time. I went back to a 26 after a bout of illness and the 29 still had the muni setup.

Quickly got used to basic riding especially as the 26 has 114 cranks while the 29 has 125s. Much the same ratio. The lower rolling resistance and more efficient power transfer impedance was very evident. The timing felt a bit odd over the tricky spots.

I noticed mounting that I often landed my foot where it would be better placed for the shorter crank. I find that surprising since I assumed the aim was all about foot-eye coordination with the pedal I was looking at.

32 inch rim x 125 mm hub would have the spoke geometry of a conventional 26 wheel so very solid. With big diameter wheels the 100 mm hub (80 something at the flanges) can reach beyond ideal especially if adding an inboard disk.

The wider hub puts the rider’s feet further apart. Whether that is good or bad depends on the rider.

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100mm wide/narrow hub

I’ve been riding my old 100mm schlumpf 29" with inboard disc (only) on the road for about 4 years without any problems. no loose spokes, no out of normal flex for the stock frame. Maybe lucky!