Crank length rules different for NUACC vs. UNICON?


My 9-year old daughter rides a 20" unicycle. She currently has 3.5" cranks on it for her artistic stuff. However, we need to get the right cranks for the track (racing) events for NUACC and UNICON.

I was reading what is posted on the Memphis Unicycle club’s site as the latest USA rulebook (usar_final_05-16-02.pdf) and in section 2.3.2, it says that a 20" unicycle must have minimum 4.5" cranks. On the Unicon XIII’s site, the IUF rulebook (iuf_rules_2006.pdf) says in section 2.2.2 that 20" unicycles must have minimum 4" cranks.

The USA rulebook is dated 2002 vs. the IUF rulebook’s date of 2006.

What rules will be used for NUACC in Memphis? The 2002 USA rulebook? It seems like the USA rulebook tries to follow the IUF rules mostly, and the 2002 USA rulebook has it marked that its crank-length rules were consistent with IUF’s as of 2002.

What is the definitive story?

Scott Barnhart
Panther Pride Demo Team parent.

For those who are allergic to inches… 4.5"=114mm 4"=102mm.

What would be even more interresting would be the minimum legal size fo 24" unicycles, I heard 125mm (5"), since this is the only allowed wheel size for athletics.

Barn, it looks like you are correct. I was not aware of this discrepancy, which IMHO is a result of the USA book not being updated recently. In IUF we changed the crank length for 20" to match up with the Japanese rules, because a very large number of 20" racers were from Japan.

Had I realized this earlier, I would have petitioned the NAUCC organizers to allow the 102mm cranks for this year. But now it’s too close to competition time, and riders who have 114s and not 102s would be at a disadvantage. So for optimum performance you’re going to want two different pairs of cranks. Or, if racing isn’t that serious for your daughter (yes her, not you) you can just stick with the 114s so she doesn’t have to adjust to different sizes.

If she’s not spending lots of hours training for the races it’s not likely to make a big difference. Check the finishing times in her age group from the last few Unicons to get a reference of the kinds of speeds to expect.

I’ll make a note of this discrepancy so we make sure it getes addressed before NAUCC 2007!


Thanks for the clarification. I will talk w/ my daughter and see what she wants to do, but knowing her, she will probably want to be as competitive as possible. I think by the time UNICON is over, I will be much faster at changing out cranks! :slight_smile:

Thanks again,

It looks like I won’t be able to do any races, since my muni (only 24" I have) wheel diameter is over the limit. Oh well, I don’t care about racing anyway.

Regarding the inch/mm thing. I can never use metric measurement myself, except when it comes to crank size. I have no clue what a 4 1/2" crank is, but I immediately know how short a 114mm crank is. I can even recognize a 150 from 165’s, and I instantly know what people are talking about when they use metric for cranks, but imperial measurement I’m lost. What a switch.

Have you tried getting a lower profile tire for your unicycle? They should fit the same rim and a slick tread should be better for road/track racing


How about crank size for 24" wheels ?

For 24" unicycles the minimal crank length is 125mm (which is slightly shorter than 5"). This minimal crank length for 24" racing unis hasn’t changed.

I think there should be a rule that requires 20 mm. cranks for NAUCC:p

Good suggestion. Also remember the offroad (MUni) events don’t have wheel size or crank length limitations. So you’re good to go for any cross country, downhill, uphill or unlimited road races.

Re: Crank length rules different for NUACC vs. UNICON?

On Wed, 14 Jun 2006 14:57:30 -0500, bbraf wrote:

>For 24" unicycles the minimal crank length is 125mm (which is slightly
>shorter than 5").

This is NOT consistent with the current IUF rules (applicable to
UNICON 13), which state:

“For 24” wheels, crank arms may be no shorter than 125mm (5”).”

So the rules seem to equate 125 mm to 5", while 5" is actually 127 mm.
That means that someone who reads that and only uses imperial
measures, effectively thinks he cannot have cranks shorter than 127
mm. This could well mean an unfair disadvantage of 30 seconds in a 10
km race as compared to riders with 125 mm cranks, which is certainly
not negligible.

I have objected in the past about this discrepancy in the IUF rules
(and other similar ones) but it is still there. I would advocate the
exclusive use of metric measures in the IUF rules. If so desired by
the Rules Committee, the conversion factor could be stated in brackets
with all decimal places known, e.g. (1" = 25.4 mm).

Klaas Bil - Newsgroup Addict

“I’m slowly but surely stealing Wales and bringing it back to my house on the wheel, frame and cranks of my muni. - phil”

The revolution of a 125 is 1.5% shorter than the revolution of a 127, which is negligible at our level. It’s true that if you make a simple equation you might wanna think that it leads to 1.5% more power hence a 27s advantage on a 30min long race. But all it gives you is less torque (which on a uni leads to more speed), so it might be an advantage on flatland, but the scenario is different when you go uphill.

Plus anybody who is serious about unicycling and who stands a serious chance, whether he uses imperial or metric will know he can get that 125mm cranks rather than 5".

I agree with you though, using imperial system in an internationnal federation is outdated and irrelevant, they should really drop that reference -even though everything in a cycle has an imperial friendly lenght (seat posts, pedal threads, cranks, rims, you name it…).

I assume there evidently won’t be any crank limitation for the Marathon, how about the 10k ?

I assume you’re question is about the races at UNICON XIII.

The Marathon is run as a Unlimited race only. So no restrictions concerning wheelsize or minimal crank length are applicable.

The 10km race is run both for the Standard wheel sizes (20" for U11 and 24" for 11Up) and as a Unlimited race.

For the Standard 10km race the appropriate IUF Rules apply and for the 10km Unlimited it is the same as for the Marathon.

So the answer is: it depends on what you are registered for.

Yes indeed, I was talking about the Unicon. Thank you for your answer, I was slightly confused.