Cranck Length at unicon12 Japan 2004

One of the news at is that 102 mm crancks are allowed in races. This should have been approwed by the IUF. According to the rulebook at that change has not been incorporated.

Can we please have some response if that is the new standard?

If it is it is very welcome!! I (Lars Lottrup) havelong thought that 114mm was way too long.

Looking forward to a fast UNICON!

Lars Lottrup and Jesper Andersen

This change was made for the 2004 rulebook:

However, it is not official yet as the IUF officers have not approved the new rules yet.

JUA proposal: 102mm cranks for 20" unis

The JUA proposal for the 2004 rulebook affects 20" and 16" unis only!
The Japanese have been using 102mm cranks for quite some
time on there 20" unis (U11 category riders) and 89mm on there
16" unis.

So, this new crank limit rule will only be of interest to you,
if you’re younger than 11 years and ride the 20", or even younger
and still ride a 16".
There is no crank limit change for the 24" unicycles!

There might be two 28" races at Unicon XII without crank limits.


20" unicycles can be raced up to age 12 at UNICON XII, I believe. Even in Japan, 24" wheels are still raced with 125mm cranks, except in special, unlimited races.

Official track racing sizes:
24” wheels with 125mm (5”) cranks.
20" wheels with 102mm (4") cranks.
16" wheels with 89mm (3.5") cranks.

These dimensions apply to most races, excluding High and Long Jump, Trials, and MUni events. The regular category in the 10k also requires standard track unicycles. You can use larger wheels and/or shorter cranks in the unlimited category in the 10k.

However. The big new thing this year, which is not included in the web site FAQs (because it came up after all that was written), is the introduction of the 700c category. At UNICON XII this will be a demonstration event, with races of 100 and 1500 meters. 700c means wheel sizes up to 29". We’re talking Schwalbe Big Apple and similar. Quoting from the 2004 rules (not yet formally approved):

· For 700c racing, unicycles must have tires larger than 24.333" (61.8cm), but no larger than 29.5" (75cm).
· No restrictions on crank length.
· Aside from this, 700c unicycles must comply with all other requirements for racing unicycles.
· Age groups for 700c events will be determined by the convention host, based on the number and age of participants.

NOTE: NO MINIMUM CRANK LENGTH! Go crazy, guys. The idea here is to see what works for people. This rule may change as the 700c category becomes more common.

The intent is that 700c will eventually replace 24" for the championship races. The 24" category will remain for many years, but may be more for younger, or more casual racers. But for UNICON XII, this is a demonstration category, and as such is not part of the world champion process. Though each of the new races will have winners, which means world champions in those events, the overall world racing champions will be riders in the 24" races. The 700c events are open to all riders in addition to the 24" events. You just need a big enough wheel…

On a side note: exactly how does one transport a 700c unicycle to Japan to race in the demonstration category? Because I don’t want to go to the trouble of building a 700c wheelset and frame just to be thwarted by customs officals or airport security.

Matt- going to Japan for UNICON XII!

Hi John,

What exactly constitutes 24"? Would a 24’ uni with, a 3’ MUni tyre be legal?

Plan for me is probably to bring a 24’ MUni, 36’ Coker and 29’er to focus on the MUni/distance events.


You should be able to pick up a wheel bag from most bike shops. They tend to come with high end racing bike wheels. I’ve got a Mavic Wheelbag which holds my 29’er quite nicely. Just line it with cardboard or corrugated plastic for added protection, and when you get to your destination the bag can be folded away to next to nothing.

Re: Cranck Length at unicon12 Japan 2004

On Wed, 28 Jan 2004 12:18:56 -0600, johnfoss
<> wrote:

>Official track racing sizes:
>24” wheels with 125mm (5”) cranks.
>20" wheels with 102mm (4") cranks.
>16" wheels with 89mm (3.5") cranks.

To be somewhat picky (triggered by the word ‘official’):

For each of these three categories, the stated length in mm is
different from that in inches. I’m not sure how close contestants in
the races are but it might matter, and it seems careless anyway. I
suggest that the official statement mentions the length in only one
unit, or in both units but then exactly the same. In addition, now
that we’re on the subject: I assume that these are not prescribed
exact lengths but minimum lengths (with some tolerance). When measured
accurately enough, a crank well never be exactly a round number of mm
or inches, and/or you run into definition problems.

Klaas Bil - Newsgroup Addict

I have a feeling you might need two points of contact with the ground for such a thing to work? Or at least training wheels on the front and rear. - John Foss commenting on a picture of a one-wheeled vehicle he saw on RSU.

A 24 ft uni with a 3 ft MUni tyre doesn’t constitute as 24 inches! :stuck_out_tongue:

Haha, Ken has been caught out again at his old habit! I don’t think a 24x3" MUni would qualify to race in a 24" unicycle event. It measures almost 26" and that surely would be outside the specifications required. The races we held on the NZUni weekend were of all sizes and crank lengths, making it a bit unfair and not very official, but it was fun all the same and allowed us to use what we had. I beat a couple of 29ers with my 24x3" in the 100m and 400m races, so wheelsize and crank length doesn’t determine your speed, but it does help. I bet if Ken was on his Coker he would have caned me though.

Good question. The bags I use have been just right to fit a 24" wheel, a MUni wheel and a 20" Freestyle wheel. Adding a 700c wheel to that will probably not fit the bag. I’ll have to decide which one to leave out! Probably the 24". I can borrow one for those few events I’d use it for, there should be about a thousand of them laying around.

I transport my unicycles in a soft-sided bag with a hard bottom, wheels, and zippered extensions. Search other threads for my detailed descriptions. Weight will also be an issue if I simply add a cycle, without taking one out. I paid overweight charges last summer for NAUCC.

Quoting from the rulebook:

For 24“ wheels, the outside diameter of the tire may not be larger than 24.333“ (61.8cm).

Add .333" to 20" and 16" as well. So far this has served us well, with nobody ever showing up with a 24" tire that was larger than that limit. That size also allows skinny sew-up type 26" wheels to race in the 24" category. They’re that small.

For 700c, we’re allowing up to 29.5".

Re: Re: Cranck Length at unicon12 Japan 2004

Klaas is right. We don’t have a problem with manufactured cranks, which are almost all built to specific common lengths (in mm). Issues can arise with custom-made cranks, which would require measurement by hand.

I have devised in my head a tool for doing this, which would consist of two pointy cones connected by an adjustable ruler. Sticking the points of the cones into the two holes in the cranks would hopefully give a convenient and accurate measurement. So far we have never needed one.

Same issue with tire sizes, such as with Marc Haefliger at UNICON 11. He had the 26" skinny tires, which he had measured and gotten cleared with the Referee (me) in advance. Sure enough, people were up in arms at the track, complaining about his “illegal” wheel. It wasn’t.

Yes, they are minimums. Everyone is welcome to actually check the rulebook to see if we missed anything else.

So far I don’t remember any instances of top racers using off-sized cranks, except in unlimited races (tiny cranks on 24" wheels). All the cranks we see out there tend to fit the nominal sizes commonly available, which come in the size increments you can see at, for instance. Most of these odd sizes, like 89mm, appear to be based on inch measurements from older designs. For example, 5" is closer to 127mm. This makes both 5" and 125mm legal.