Have been reading a lot about people speaking of crank length and their differences. But still couldnt get a clear picture of which is better for what.
Can i ask, a longer crank is better for trials or?? and a shorter crank??
Someone would be so kind and nice to explain? Thanks!! 
It’s all relative. Different people will have different ideas of what is “long” or “short”.
Some common crank lengths in millimetres are:
89, 102, 110, 114, 125, 127, 140, 150, 152, 165, 170
On the whole, longer cranks give more “torque”. That is because you have a longer lever. That means it’s easier to turn the wheel when you’re climbing a steep hill, and easier to control your speed on a long down hill.
On the whole, shorter cranks make it easier to spin the wheel fast. That is because your feet doen’t have to move in such a big circle, and your knees don’t have to go up and down so far. However, because a short crank is a short lever, hills are harder work, or more dangerous.
The length of crank isn’t the whole story. 150 mm cranks on a 24 will give you a machine that is very good on hills. On a 20, 150s will make the uni will silly to ride, and the pedals will clip the floor when you turn. On a Coker, 150s will feel about right for general use.
110s on a 20 will give you a buzzy little machine that scoots about very fast. On a Coker, they will produce a speed machine that takes some taming.
You also need to take into account your own level of ability and experience . And if you are very tall or very short, that will affect your choice.
I’d guess for trials you’d want medium-long cranks. 125 - 140?
I ride 140s on my trials uni. I love em. They are short enough so that i can give a quick blast of speed for rolling hops/gaps and they are long enough to give great ontrol on riding skinnies and doing drops.
Hi Alvin, are you the guy from Singapore? If so, get in touch with Kai Lun…He is a very knowledgeable unicyclist and is pretty good too…You can ride his custom 26"…It has the Onza hub crankset and a real cool and unbreakable frame that he designed…You should definitely take up his offer of riding with you guys…
i use 125mm on my 24" uni. i ride pretty much everything so i rekon its good for all round purpose and i havent come across a really steep hill that i couldnt get up on them yet so im doing all right, plus u can abosulty fly along on them.
If you have a larger wheel, I suggest that you fit it with shorter cranks, it will be beneficial for many reasons:
I ride a 26 incher fitted with 110 cranks in Paris, whenever I ride on a daily basis jumping and hopping just seems easier on my trials uni.
Hi there! I’ve spoke to kailun already, i wanted to ride with the sg unicyclists but it always turn out that i’m not free during the days of the events.
Definately will find a day to come riding. 
Thanks guys for your replies, i roughly got an idea.
I’m interested in getting to streets/trials so im thinking of which length i should get. Getting a 20 inch and my height is around 1.72m so any recommendations?
Here’s what we’ve found so far as Muni goes:
With no brake:
Super steep (descents) technical: 165/170
Steep technical and hard rolling: 160
Free ride single tracks (like normal Mt Bike trails): 150
With brake (all terrain): 160 if in decent shape; 150 if you’re in world-class shape
150s work fine (with some getting used to) for even hard climbing, but sans brake, when descending steep rock faces, et al, you can’t back pressure the 150s enough and spinning out of control becomes a factor.
That’s just a general indicator. Individuals might prefer otherwise.
JL
Hi Alvin!
I ride trials and was in the same dilema you are in, a few weeks ago.
Most people who ride trials ride 140mm cranks. They’re pretty standard.
If you want to get into more street style* riding then you might want to 127mm or 125mm cranks. They give you some extra speed for rolling hops and will probably make freestyle skills easier!
I went for 125mm K1 cranks because I want a balance between freestyle and trials.
Hope this helps, AndyC
*if you are unsure what this is, check out Xavior Collins on Koxx1
i ride 127s on my 20 in. i like them alot for street and trials riding.
but then again, i have never tried any other length on my 20 in.
i have 140 on my 20" trials. they are sick.
ditto and they work fine for trials
Do you mean Xavier Collos 