trials crank length/spoke count

Hey All,

What is the most common (I know, there are always a pile of exceptions to every part!) crank length on trials UNIs?

A number of years ago I lead the charge to get biketrials to use 32 spoke wheels instead of 36. Many years ago there was a reason for more … but now the spokes and rims are so much better, the logic was lost. So we switched opening us up to use a much larger variety of rims. Similarly, is there a good reason trials UNIs are still 36? The spokes are so short and close together, if you run a simulation you have to get into the theoretical before it makes even the smallest (and it is small!) difference. Is is like BMX bicycles using 36…strictly history/habit?

I would love to have a 32 hole hub.
I could use the DOB Magnesium rim with no problems than…

I prefer something between 140mm and 145mm for trials.

In my opinion the 48 spokes is mandatory if you wanna feel safe on large drops. E.I. 5 foot and on.

For trials, the most favorited is probally 140ish and a bit shorter for street. KH moments at 137mm are really popular.

But unicycles still use 36 spoke although some use 48. A lot of people want unicycles to change to 32 so they can have more rim choices.

The only reason the 137’s are more popular is because the people that buy those unis also do street. and longish cranks are better for crankflips. I want moments :slight_smile: im ditching those dx cranks soon!

I use 125 mm moments for street. Though i havent tried 137s much, i think 125s are more flippety.

I admire your word ussage. flippety. i think i shall go do some flippetys now. :sunglasses:

but you gotta ask yourself one question, does the dude abide?

Wouldn’t shorter cranks be better for flipping because they could spin easier…

Although I’m not in much of a position to talk because I still can’t crankflip:p

you would think but think of this. the reason trials cranks are long is because when your on thick to thin you bumpy you need really good leverage, therefore you needing long cranks. sooo when you jump into the air and kick the cranks, there spining with velocity… and when you try and land on those short little cranks you may just keep on going, whereas longer cranks you have the longer leverage to spot them from spinning on.

the dude totally abides and i liked a video of yours but i dont remember which one all i remember is that staircase and your little picture is one of that staircase so yeah, your cool :sunglasses: , im cool :sunglasses: , we are all :sunglasses: cus we ride uni’s and only :sunglasses: people ride unis cus there :sunglasses: . word.

I would never want anything longer than 140mm cranks for trials, after that it gets hard to ride skinnies because you wobble.

I would love to have unis go to 32 hole. I don’t really see any reason for them to stay at 36.

For years trials bikes were predominantly the 20/19" versions, and ran shorter cranks 152-155. Mid nineties Monty went to 158s on its higher end mod (20") bikes. Late '90s Megamo (now out of business) introduced 170s on some models of mod bike. It took a few years, but for the most part…now mod bikes use 170s. The reason, more leverage for a bigger move.

Strictly considering trials (freestyle aside), does the same line of thinking apply?

not really, at least in my opinion.

if all you are doing is hopping, than I would imagine that yes it would be good, but a lot of trials is riding skinnies and doing lines that require some rolling, and there is where you don’t want really long cranks.

If you have strong legs you can get enough leverage out of 137’s/ 140’s, at least that’s what I’ve found.


Thanks Miles,

So I guess that 145 is really the upper end of things. I was not suggesting that UNIs might want 170, just what things are different and what is considered the longest useable size. In biketrials, it was really the power of the riders increasing over the years that pushed the size up. I do understand that on bikes you have gearing to contend with (that has gotten steeper over the years…hence the longer cranks). So the longer the cranks (further from the spindle), the more wobbly things get… that is something I never thought about…interesting.

Does anyone know how long UNI trials cranks were a few years ago? Or have they always been about the same length?

Years back almost everyone was riding 145mm because profile was the only option for splined uni trials cranks and that’s the shortest they come. When Kris Holm produced his first trials hub/cranks in 2003, they were 140mm. Now most trials unis come with 137/140mm cranks, the exceptions I can think of are torker (125mm) and qu-ax (145mm).
I personally like 137/140 for trials and 125 for street/flat.

Well for a long time profiles where the only really strong splined cranks you could get for unis, and they came in somewhere between 145 - 150 mms.

Lots of people rode them and did amazing things on them, but they have always felt pretty long to me. I could probably get used to them, but I would rather ride slightly shorter cranks.

edit: spencer beat me to it.

another factor is wheel size. with a mod rim, your cranks can only be so long, unless you intend on never turning while riding a unicycle. i can’t imagine going longer than my 145mm (i think someone found out that they were really 150mm) profiles, because on some sharper turns i do bump the pedals on the ground. very rarely has the force been enough to knock me off my unicycle. it only happens once in a while, and not just with turns, but sometimes from riding on steeper surfaces.

as far as spoke options go, i’m no expert, but i would assume that it has to do with the unusual forces and strains unicycles put on rims.

i for one, as a uni trials rider, am very skeptical about drilled rims, let alone 32 spoke wheels. i will probably never ride a drilled rim, ever! i just don’t think those things are strong enough for what trials unicycles are put through. someone correct me if i’m wrong.

Another point I had not thought about, in reference to crank length. The spindle on a bike is higher than that of a UNI, certainly making a difference when it comes to clearance and length… good point.

Per the spokes. On a 19" wheel, laced taught with good quality spokes… the difference between 36 and 32 in strength is only something that makes difference in the theoretical.

As for drilled rims. Most of the strength of a wheel is in the tension of the spokes. A good wheel build will make even a truely crappy rim appear to be strong.

On my BMX I run a standard set of cranks which are 175mm in length, so yeah the height of the axle is very different.
I tried some 170mm cranks on my uni just to see what they were like and I found them to be pretty intolerable. They were just too easy to pedal with, which made it feel very, very bouncy. Not to mention I kept catching the pedals on the floor!
I have only ever used 125s so I’m not really sure what 137/140s would be like, but I’m more into street but getting into trials, so things may change soon.

I’ve only just noticed that the Nimbus Isis trials comes with 125mm cranks. Anyone know why? Is it just due to cost?