Wheel/crank size recommendations for commute and road riding

I’ve had a unicycle for about 15 years but only just got around to learning to ride it. I can free mount and ride continuously for about 1.5 km without too much trouble. Yet to learn how to idle.

My current uni is a 20” with 127 mm crank arms (inseam 32” - measured as top of pedal in bottom position to saddle with saddle adjusted as high as it can go). My inseam is ~34” (including shoes), and i’m 6 foot. It feels a little short as I can’t get my legs anywhere near full extension.

I’m moving countries in a few weeks to somewhere pancake flat. I likely won’t take the 20" with me, so before I go I aim to learn to idle and be comfortable riding longer distances.

I’m looking for something I can both commute on (with backpack) and ride on weekends for exercise (ideally 10-15 mph for 1-2 hours) and to explore.

I had in mind getting a 29” with 90-100 mm cranks arms.
Any advice or other factors I should consider when looking for a uni?

29" sounds good, it’s by far the most universal wheelsize, and although you can definetely expect needing some practice to get used to the bigger wheel, it will be a lot more manageable than the jump from 20" to 36" would be.

90-100mm is probably too small if you just learned, cranks are cheap, start with some 140mm cranks on the 29", then get shorter ones as you progress.

Search function

Welcome, I see you are new to the forum. Please learn to use the search function, this has been beat to death with such great information in previous posts.

Welcome to the forum

29 is probably a good choice, but I would start off with 125mm cranks, Its a size you are already used to and you can move down to 100mm after that.

I made up this chart a few years ago to show roughly equivalent wheel/crank combos

I quite liked doing what you describe with a 26"/100mm combo.

I agree with using the search function. However, in this case, the OP gave a lot of information and specifics about his own riding. That makes determining the answer more complex, because it involves synthesizing all the information the OP presented.

A 29" sounds like a good choice for the riding conditions you described. IMHO, even if you learn to idle on your 20", it’s not going to be very easy or fun on your 29", especially if you’re using shorter, commuting cranks. If your reason for learning to idle is to avoid dismounting at intersections, please be advised that it’s safer to get off and walk the unicycle across the intersection. Your visibility behind you won’t be good while riding, and half the drivers may be on their cell phones. I suggest putting in the time learning to self-mount on the larger wheel. I think John Foss mentioned that when you walk your unicycle across the street, non riders will wonder how you’re going to get back on. And when you mount, they will find out. I’m a big show off, and I’ll frequently jump-mount my muni after walking it across the street at a big intersection. Be safe.

10-15mph is pretty fast. A UPD at 10mph is UPDing into a 6-minute mile run. A UPD at 15mph is UPDing into a 4-minute mile full out sprint. If you’re serious about those speeds, you might be looking at a 36" wheel. Make sure to wear a lot of padding, as you are likely to not land on your feel at these speeds.

I believe that learning a variety of basic skills (mounts, idling, backward-riding,hopping, etc.) on a smaller wheel… will help your basic riding on the larger wheel. At this point in your unicycling progress, you might at least consider taking the 20" unicycle to your new country, working on skills a while longer, making the commute on the 20" just to get the lay of the land, then buy your new unicycle. Your local bike shop may be able to help you find a longer seat post for your 20".

Good luck, and welcome to the forum!

Here is a past thread on the “Average Cruising Speed of a 29” Unicycle":

Expecting 15 mph out of an ungeared 29"er is likely not realistic for normal touring.

Note that Coker = 36" unicycle.


Thanks for the help everyone. I researched some other threads before posting, and these replies have given me some new considerations!

Think I’ll try and take the 20" with me and get a bit more proficient before moving up.

A year or so ago, I went through a phase of commuting in which I tried 20, 24, 26, 28, 29, and 36, with various crank sizes. I concluded that 29 with 125mm cranks gave me the best versatility: reasonable speed on the straight sections, good control around people, safe and fun.

Different routes and different levels of skill and experience would change the emphasis. However, 29 inch with a medium length crank is fairly fast and safe enough.

For comparison, I am comfortable riding my 36 in rural traffic on 150s.

Thanks for the advice.

What do you think of having brakes, are they necessary? Just not sure how quickly I can come to a stop if need be.

I like brakes for my 29s because then I can take advantage of the momentum instead of having to keep it “in check” in those just in case circumstances. I always know I can stop if I can stay upright.

It’s also an equalizer if there’s more downhill/cross country muni in your future.
It’s great to feather the brake for a smoother ride downhill as you don’t need any of the pedalling energy to assist in slowing.

I like handlebars as well. They tweak everything up nicely.

This is what works for me.

If you are moving to someplace that is “pancake flat” then unicycle brakes would likely be of little use. Brakes on a uni are almost never used for stopping but are used almost exclusively for riding downhill. For road distance riding they really save your legs on long downhill grades and allow you to safely ride much faster down steep slopes.

With that said, they can be used by an experienced “unicycle champion” for stopping. The first few seconds of this video makes it look easy but I bet it is not.


I have been using a brake for 3 years, and I cannot do what you’re describing. Coming to a quick stop, using the brake, seems like an advanced technique, kind of like braking down a hill and lifting both feet off the pedals. For me, braking is a very controlled, gradual thing. I start putting on the brake before the hill comes. A novice user of the brake described it, on the forum, as an “instant UPD button.” A very experienced 36" rider using short cranks could, I suppose, brake very suddenly, but they would have to get the wheel way out in front of them prior to braking, feather the brake and pull back on the seat/bars with the appropriate force…all to avoid a spectacular UPD.

I suggest you (eventually) get a unicycle with a brake and start learning to use it. You don’t need hills to practice braking. But, as far as the brake being necessary, maybe not so much for the pancake-flat place you’re moving to. A lot of good unicycles ship with a brake. If you have the money for one of them, go for it.

But, for quick stops, I think you’ll be relying more on your feet.

A brake is only useful if you use it, otherwise it’s just an expensive attachment to your uni waiting to break. You can use it to come to a quick stop if necessary, but that will take some practice. It’s really not as impossible as people tend to make it sound on here, you just have to not be afraid of leaning back.

How necessary they are depends on your commute. If it’s a mostly quiet bike path, I wouldn’t go for one, if it’s inner city with cars and pedestrians, I would definetely think about it.

EDIT/ADDITION: Beginners will definetely need to collect a whole lot of experience before they can make use of a brake. But if you are going onto roads and busy sidewalks where a brake would help, you shouldn’t be a beginner anymore anyways…

Just a couple suggestions.
Definitely keep your 20" uni. Very helpful for learning new skills, and Unicycle dot com can provide a longer seatpost (and probably a more comfortable saddle).
If you decide on a 29" or larger wheel, a brake is useful for coming to a stop, even if the terrain is “pancake flat.” I use the brake when coming to a stop on my 32" every time, downhill or flat. I enjoy the control it affords, and would not want to do without it.
Welcome to the forum! :slight_smile:

Maybe I missed it, but is there any reason you’re ruling out a 36"? They’re great fun and will meet your requirements nicely. 125/127mm cranks on a 36 are a good general purpose length, and will let you cruise on sealed and unsealed roads with some moderate hills thrown in.

A brake is handy for hills, but if you’re going to be somewhere flat then that probably isn’t a concern. I do find myself using my brake for stopping on my big wheel (36", 127mm cranks). Not so much on my small wheel (26", 137mm cranks), as it never really builds up enough momentum to require it.