Crank length

Hi, I am wondering what size crank I might want since I am getting a new unicycle soon. At the momentvi am using a home made unicycle with bike cranks that are like 200 mm. The pedals touch the ground when I turn sometimes. So I obviously am going to get ones that are shorter than that. But as I have only ridden one unicycle I’m not sure what’s best. I am going to ride some trials and flatland. I would just like to know what some people would recomend.


Um, what sized wheel are you riding? That could make a big difference, and do not go over 150mm on any wheel.

Oh ya, sorry about that. I’m riding 20 inches ,thanks.

for 20" it depends what kind of riding you do, but dont go longer than 140mm.

good advice.

Just so you know most bike cranks are 170-175mm You measure from the center of the axle hole to the center of the spindle hole. Not the whole length of the crank.

Oh, I didn’t know that. So your right, they are 175mm.

Thanks everyone, when the time comes I think I will get 137mm.

I don’t agree on that. For MUni 165mm cranks are useful on wheels bigger than 24" or if you are using a geared hub.

sorry, i don’t know much about muni.

To be honest, I’m not sure about 137s either. I still hit the ground with 125s on my 20" and wouldn’t recommend anything longer than them (125s) for regular riding.

you must be doing some sharp, sharp turns then, because i have both 125’s and 137’s, and the 137s rarely, if ever, hit the ground. all i do is trials though.

137-145 is the best for trials imo

It seems like you can only get Kh moments in 137mm and higher.

I just checked four UDC shops (US, UK, Australia, Germany) and they all have 125mm moment cranks (and even shorter ones)

I am looking at And it’s an upgrade on the nimbus trials and it only shows as low as 137mm unless you get double hole. But thanks anyway.
So, to the point, you guys recomend that I get short cranks? Like, 110mm Or 125mm if I can?

Indeed you can’t select the 125mm moments here but since the description says “Available in lengths of 110, 125, 137, 150 and 165mm” you should just ask them at Maybe 125mm cranks are out of stock just for now.

Regarding length I would recommend 137mm cranks anyway. You will be able to learn all flat tricks with that length but you have more control for trials.

if you’re gonna be doing trials and flat get at least 125mm, not 110.

and you can probably email them and tell them you want a pair of 125’s instead of 137s if you dont want 137s.


just get 137s

Thanks, I’m not too worried, I’ll probably get 137mm. It sounds about right for what I want to do.

That’s interesting. I stopped using 125s (for Freestyle) because the pedals hit the ground way too much. The Schwinn 20" used to come with 140s! I used one of those at Unicon I to win the Pairs competition. Just goes to show how important it is to know what riding style the person is talking about…