138mm cranks on 19" trials

I’ve been going to meetings for a local college-based unicycle club, and they’ve gotten me into doing trials and flatland stuff. My wife just got me a 19" Nimbus Signature Trials, and I’ve been having lots of fun with it. It came with 125mm Venture II cranks, and it feels very familiar with the wheel size and crank length. Over the past 30 years, all four of the 20" unicycles I’ve owned and ridden came with ~125s, and that always seemed to be just about perfect. (For anyone not familiar with 19" trials unicycles, the outer tire diameter works out to be about the same as a 20" with a regular tire.)

But, after trying to up my game with the trials stuff, it was suggested that I’d need longer cranks (like 137-138mm) for more stability for jumping and hopping. I decided to swap out the cranks with 138mm Venture IIs since I already owned those.

It’s been a little weird. Compared to the 125s I’ve been used to on a 20" wheel over the past 3 decades, the 138’s just seem a bit long and awkward. While it does seem to provide some additional stability for hopping and jumping (although it’s nothing earth-shattering), it makes pedaling SIF much more difficult, and just pedaling in general is more difficult. It’s also made some things, like one foot idling, a little more challenging.

And the crank length is not all that’s changed. With the longer cranks, the saddle at its previous height was too tall. Plus, it was probably a bit too tall with the original cranks to begin with, but I was going to have to cut the seat post to lower it any more, and since it was close, I just dealt with it. Now, I’ve cut the seat post and lowered the saddle to a more ideal height, and my center of gravity is lower. That seems to directly effect things like one foot idling, and not just because of the lower center of gravity. I have to raise my foot even higher to rest it on the crown, which will also effect one foot pedaling and coasting.

I’m sure that part of it is just getting used to the longer cranks, shorter saddle, and another part may be that I’m trying to mix flatland stuff with trials stuff. It seems that most flatland folks are using shorter cranks, and the trials riders are using longer cranks. I guess I could get some dual hole cranks, but I’m usually mixing it all up, and re-positioning the pedals doesn’t seem very convenient.

I guess I’m looking for input from those of you that mix it up with trials/street/flatland and what size cranks you’re using, or if there are flatland riders using longer cranks, or conversely, any trials riders using shorter cranks. I have a feeling that there is no ideal solution, other than either changing crank length, and that there will be a compromise. If that’s the case, the question I have to answer is, what is the best compromise?


I use my 137mm KH moments for everything (trials, street and flat), I switched between them and 130mm groovies 2 times in the past. Both were good, the groovies just killed my ankles and since I didn’t like having my ankles bleed constantly I switched (back) to moments. You notice the difference, but you get used to either.

I know people with 125mm cranks riding almost only trials and doing 110cm hops with them, so I figure they are pretty ok. Almost no one does flat with >130mm cranks anymore though, so I would say if you were going to buy new cranks, I would recommend 130mm mad technos or 125 QX ZeroQ as good alround cranks that do rolls, flips unispins and most trials stuff quite well. I think long cranks are more of a disadvantage in Flatland than shorter cranks in Trials, so I would compromise with using the short ones. You get better control in trials with 140mm, but not that much, but triple flipping a pair of 140mm cranks makes your wheel wiggle all crazy, while 130mm leave it calmer and flip faster.

Use whatever you enjoy, I wouldn’t bother with changing between them, or dual holes, get used to one or the other size and stick with it. This is the voice of a poor student though, and I would much rather spend 90€ going to EUC this winter than spend the money on new cranks, even if they would make my riding a bit better.

Cool. I appreciate the insight. I’ve spent way more this year on unicycles, parts, and accessories than I had the budget for, so I’m pretty keen not to spend any more than I have to, so I’ll likely just get used to the 138s. I’m not quite up to crank flips just yet (but that could change by this weekend!), but that is on the horizon, and it would seem that the 138s would not be good for that. I may want to go back to the 125s at some point, or if I get a little extra in my unicycle budget, or can find some used, the 130s might to the trick. I’ve also got a lot more friends now that do this stuff, and they likely have spare cranks lying around that I might be able to try out.

Thanks! :slight_smile:

One of the good things about short cranks for flatland is that you can make sharp turns or even pirouette without your pedals scraping the ground. Short cranks also give you a faster ride.

My 138mm Nimbus Venture 2 cranks got a bit loose and floppy, so I put on some 110mm Kris Holm Moment cranks that I had, which seem to have a broader interface with the hub. They don’t wiggle at all, so I guess the loose Ventures didn’t do any damage. I have no problem with one-footed idling, but one-footed riding is now significantly harder. The shorter cranks leave less room for error. Their high Q factor -10mm or so- may also be a problem. It seems harder to ride one-footed in a perfectly straight line now, but that might not be due to Q factor. In any case, one-footed rides of 100+ revolutions are a thing of the past for me now; I’m lucky if I can even get 20 revolutions before UPDing.

For sidehops, my 110s seem totally equal to 138s, though the transition from riding to hopping may now be a tiny bit slower- in other words, I have to stop and pogo stick for a moment before I head up the stairs or onto the curb. I have been told that short cranks are definitely not as good for forward hops or rolling hops (same thing?), but since I barely do those things yet, I don’t have first-hand knowledge. 125mm cranks, I would guess, might be a good compromise- not long enough to scrape the ground, but they’ll give you a bit more leeway than 110s.

Hi Bradford

I agree that the change from 125 to longer cranks doesn’t feel right. I changed my ventures 125mms to some cheap ‘Indy brand’ cranks 140mm and I also found more difficult to do the things you are mentioning: as you say pedalling with longer cranks is not as smooth as with shorter ones.

I’ve got used to it in the end and I am still using the cheap 140mm cranks ( I should upgrade to better cranks some day, maybe KH moments). I am basically able to do the same things with the 140mm than the 125mm but with the longer cranks I think I find it easier not to miss the pedal when landing a rolling hop for example. Also I think it gives me more leverage to do jumps/hops SIF …

I am still pretty much useless at Trials/flatland etc… so don’t listen too much to my advice. One thing for sure, probably it is because of my age and my attitude to take risks, it takes an awful amount of time and practise to get better at it :wink:

The only time you should have issues with pedals hitting the ground and long cranks is when trying to do freestyle. The speed of shorter cranks helps with long jumps (which is why street riders like them, those stairsets can get quite large), but make them harder to land at the same time.

Interesting, I always found shorter cranks easier for one foot, they automatically make my riding smoother. One foot is not a trick I would do on my 19" a lot though, only on my freestyle, and even then only long enough to transition to gliding.

110mm cranks on a 19" are usually a choice of flatland riders that want super fast flips, if you want bigger hops you usually go to 125mm. It definitely takes away some control, and it is usually only a choice of very good riders, since it makes landing after a trick much harder. For sidehops it makes not that much of a difference since you don’t carry forward momentum, but for anything that involves facing forward when landing, the change in leverage is significant.

I’ll have to keep on eye on the Venture IIs. I have them on three unicycles including my muni that I’ve ridden quite a bit, and so far they haven’t started to feel loose, but I doubt I’ve put them through the beating that you have. If I notice they’re getting loose or floppy, I’ll have to change 'em out so they don’t damage the hub. Thanks for the heads up on that.

That’s also interesting about your issues with shorter cranks being harder than longer ones. That’s a big difference between 110s and 138s!

The problem might have been that I rebuilt my wheel twice, so I removed the cranks a few times. Maybe once I didn’t put them back on tight enough, though I doubt it, and my crankbolts have never come loose on their own… anyway, yeah, keep an eye on them.

All my non-distance riding is on a KH20FL wheel. I always put the fattest possible tire on it (20 x 2.45), so it’s sort of halfway between freestyle and trials.

That would include riding down the stairs, wouldn’t it? I am still a bit shy about doing that, and have never ridden down more than three steps at a time (unless you count steps that are insanely wide).

Hey, since you mention gliding, is there a way to know which foot I should use to start learning one-footed wheel walking? For two-footed, my right foot always goes on the tire first, and I usually idle left-foot-down. Also, I have only learned one-footed riding on my left foot…

Cool discussion, song! I’m interested in all of this. I won’t hurt my feeling if this thread get hi-jacked into any direction. This is all good stuff! :slight_smile:

I do pretty much the same as you, and I use my right foot for one foot wheelwalk and gliding. It just makes the 1 foot to gliding transition easier. That way you can also practice fast one foot ww to practice gliding.

I always recommend using whatever foot/hand/direction you are most comfortable with, it only really matters on unispins (spin towards front foot is better for bigger spins). It’s almost always very clear what foot I prefer to me. But I also practice everything from a transition, so I never end up with situations like: “Oh, I wonder if I could link one foot wheel walk and standup ww together” - and then noticing I use different feet for it. (Happened to someone)