Hello all.
At
https://www.pattakon.com/pattakonUni.htm
a 36er unicycle design allows as short saddle and pedals height as a 20er.
The difference from the conventional unicycle is that on each crank it is not rotatably mounted a pedal, but an arm whereon the pedal is supported, with a mechanism controlling the orientation of the arm relative to the frame.
I didn’t yet made a prototype.
Any comments ?
Thanks
Manolis Pattakos
Doesn’t that make the unicycle wider? What about the force when keeping the unicycle stead with heavy wind or municycling. you’re introducing multiple friction points, that need to be quite solid, so they don’t break or unscrew.
Does it improve balance having the rotation point away from the middle?
On a conventional uni, you just put your seat higher or lower.
Wow, that looks pretty neat 
What an interesting concept! I don’t really have much I can contribute with technically here, but I curious about a few things. Why would you want the pedal position to be low? To make it less intimidating to ride? Stability? The Huni Rex has similarity lower position, and the result is increased chances of pedal strike on sharp turns, and also lower reaction time when UPDing.
And on the topic of UPD, how will the frame and machinery hold up with the forces from the seat slamming the ground at high speeds?
“Doesn’t that make the unicycle wider?”
Just a little.
Above is a photo of a 20” Unicycle (Terra Bike) that shows the large clearance between each crank and the fork. This empty space can host the gears. What is left is the arm.
“What about the force when keeping the unicycle stead with heavy wind or municycling.”
I can’t see a problem. A 20” unicycle has its pedals at the same height with a 36er P@Uni. And the 20” are OK with heavy wind. The big diameter wheel of the 36er improves the rolling at rough terrains.
“you’re introducing multiple friction points, that need to be quite solid, so they don’t break or unscrew.”
The forces are heavy only between the arms and the cranks, which keep unchanged the number of heavily loaded bearings (case with pedals secured to their arms). The rest forces are dozens of times weaker leaving the “synchronizing” bearings / gearing actually unloaded.
“Does it improve balance having the rotation point away from the middle?”
The riders of Huni-Rex unicycle (center of rotation of pedals substantially lower than wheel center) can reply to this question. Are there any?
“On a conventional uni, you just put your seat higher or lower.”
On the P@Uni unicycle you can do the same, however you have also the option to lower the height of the pedals instead of lifting the saddle (case of tall rider). So while in the conventional unicycles the taller the rider, the higher the saddle / seat and so the higher the center of gravity of the rider, with the P@Uni you can, if you like, maintain the center of gravity of the rider low despite rider’s height.
Reasonably without a post the frame becomes simpler, cheaper, more lightweight and less flexible (having a saddle at the top of a long post is not the best for overall rigidity). It is also that the unicycle becomes more compact to transport / carry (with the saddle almost touching the wheel, and acting as a fender too, the maximum dimension is only a couple of inches larger than the wheel diameter).
Falling from a tall horse is way more risky than falling from a pony. Mounting on a tall horse is more difficult than mounting on a pony. But the tall horse runs faster and passes easily over rough terrains. The idea is to combine the best of the two (big wheel for improved rolling and higher speeds (geared or not), with low saddle and pedals for easy mounting – dismounting and less risky falls).
“Why would you want the pedal position to be low? To make it less intimidating to ride? Stability?
For improved safety. Also for easy of use (mounting – dismounting). Also for enabling not tall riders to safely ride 36er (or 40er etc) big wheel unicycles and enjoy the advantages of the big wheel rolling quality and speed.
“The Huni Rex has similarity lower position, and the result is increased chances of pedal strike on sharp turns, and also lower reaction time when UPDing.”.
The pedals of the P@Uni are adjustable in height. If they are too low, you simply lift them.
Above is a photo of the kinematic mechanism of the Huni Rex unicycle. The solution works but the crankshaft (i.e. the strongest part of a unicycle) is divided (=sacrificed) and each half is independently supported on its own half of the fork which needs to be substantially stronger / rigid / heavy to take the resulting bending loads. The unicycle becomes a lot wider. The power from the pedals passes from gearwheels and chains (backlash) to finally arrive to the wheel. The load on the outer central bearing of each crank doubles, and there is another central bearing (the inner one) to milk power. Compare the case with a geared P@Uni 36er.
And on the topic of UPD, how will the frame and machinery hold up with the forces from the seat slamming the ground at high speeds?
I can’t see the problem. As the conventional unicycles do, I would say.
Thanks
Manolis Pattakos.
I think this is a bit dubious. The 36" Nightfox already has the seat very close to the wheel. Having the pedals at hub height, makes the length from seat to pedals smaller, so peeps with shorter legs can ride it. By lowering the balance point, longer legs are needed.
As for improved safety, I agree with @Pedalsprell that there is a lower reaction time with UPD’ing. I experienced this hands-on at a unicycle session in a sportshall some months ago where I lost balance with my 19" trials, and being too close to the ground, my foot flipped double. It took a month to heal up.
I don’t have a Huni Rex and I don’t really see the point in having one for these reasons. It doesn’t add value to me.
As someone who’s fallen from a few unicycles over the years I’m also not sure I agree with this statement. The risk of being close to the ground is that you don’t have any time at all to react and you’re more likely to trip, wreck your ankles, and faceplant.
When riding at speed on a regular 36” you might be slightly further from the ground, but that means you’ve got more distance to figure out what you’re going to do before you hit the ground (typically moving into a position where you can attempt to do a roll). You normally want your feet to do very little aside from guide the rest of your body down towards the ground if you’re going faster than you can run out of.
When a seat fixed all the way down do the bearings (ordinary uni) slams to the ground there is no force transmitted to the pedals/machinery. The seatpost, and the seat post clamp will have to absorb the impact.
I assumed that the red cogs are welded to the red frame. In that case the force of an impact with the saddle/frame will be transferred directly through the blue cogs and the rest of the machinery. This might not be much of an issue, but a source to additional wear nevertheless.
What I like about an ordinary uni is the simplicity, and the few moving parts that actually need maintenance. If you want to add to the complexity, you have to have some really good reasons in my opinion, like for example gearing.
Your design does indeed solve some practical issues in terms of size and compactness.
I am curious about how your center of mass being closer to the wheels center of mass, together with the offset pedal position, affects your accelereation going straight, and would ability to change angular momentum when turning. Huni Rex riders migh have some insights here as well.
On the designs of the unicycle, both designs will increase weight quite notably and I can’t see a way around this.
The design with gears will have noticeable play, and I suspect the gears will wear quickly, especially as they do not have any kind of enclosure or possibility for an oil bath. Road dust and debris will accelerate this wear.
The design without gears requires 10 additional bearings and quite substantial stiffness in the additional components. I’m not sure that the design as pictured is anywhere near thick enough to accommodate these additional bearings.
On the design in general - it absolutely would need to be compatible with standard modern seat designs (4-bolt mounting typically, although pivotal also has some use), and support handlebars in order to suit modern styles of riding.
On both designs, how do you remove the wheel to fix a flat?
On a regular unicycle you remove 4 bolts and you’re good to go, with some frames now moving to simplify this further with two bolts.
On the geared design it seems immensely complicated.
On the non-geared design maybe at best it’s two additional bolts, leaving a frame with the cranks, pedals etc. still attached?
That design would also still need pedals to allow for foot flexing which happens during riding. A solid plate that is always facing upwards would be very uncomfortable for mounting and general riding.
I agree, the night fox solved that problem many years ago as this video proves with a child riding one. https://youtube.com/shorts/LOytWnX81Ho?si=GJjGd2zbSHOEp4a1i
I think unicycles attracts a lot of engineers and tinkerers that have a tendency to want to over complicate a very simple machine. You quickly run out of things to change and upgrade on a unicycle leaving you with the empty feeling of not having anything to do next. I think that’s part of the reason why so many of us own so many unicycles. I count myself as a tinkerer that owns far to many unicycles 
.
Oh yah if you want to go broke fast put a very expensive toy with a very limited audience into a market that is very limited to begin with, that will do it.
I guess I should chime in being I’ve been riding the Huni Rex semi-regularly recently.
I think at this point I can say the lower riding position doesn’t really improve the stability of riding, though I can’t say it makes it less stable either. To me, when riding steadily in a straight line or making gentle turns, it feels much like a regular uni handling-wise. Once I start getting into tighter and quicker maneuvers though I have to be very careful because of the risk of pedal strikes. Regular unis are much more confidence inspiring in that respect.
As for unplanned dismounts on a lowered uni, I’ve had a few of them so far. The good news is I’ve still had enough time to land on my feet when they happen (yet that doesn’t mean I can outrun them very well when I’m riding at speed ).
Honestly my number one sticking point with the Huni is the width of the unicycle. The Q-factor is kinda bonkers which means my legs are spread out a bit more than usual. It makes it more difficult to put power down, and it probably makes my legs a little more sore. And of course it exacerbates the pedal strike situation somewhat. I still ride it and enjoy it, but it won’t probably see anywhere near the mileage my 36er gets. If the P@Uni can manage to be narrower than a Huni then you’re probably still in an okay Q-factor range
Welcome to the community, and thank you for sharing your concept. It reminds me of this earlier discussion of a similar basal idea: Prowheel crank 127mm ISIS "MaxQ" first look - #26 by DrD.
Your description gives the impression that the mechanical design came first, and the list of benefits was assembled afterward. The reasoning feels built around the invention rather than the other way around. The design may have interesting mechanical potential, but the explanation would be much clearer if you:
Right now, the explanation mixes two fundamentally different topics. Throughout the post, you switch rapidly between technical design details (bearings, loads, gearing, crank spacing, frame rigidity) and usage / rider experience claims (safety, mounting ease, wind stability, pedal height, market needs). These domains require different kinds of evidence and different logic. When they are blended together, it becomes difficult to understand what problem the design is actually meant to solve.
Clearly separate the discussion into two sections:
At the moment, several different “problems” are mentioned:
Because these appear as a list of possible benefits rather than a single justifiable need, it is difficult to figure out:
Personally, I have thoughts on some of the technical and rider experience claims, but it is difficult to discuss them meaningfully until the overall argument is structured around a clear problem statement. Once that is clarified, it will be much easier to have a focused and productive discussion.
Thanks for your informative post.
You write:
“there is no noticeably change of the stability in case the pedals are moved lower”.
You also write:
“Honestly my number one sticking point with the Huni is the width of the unicycle. The Q-factor is kinda bonkers which means my legs are spread out a bit more than usual. It makes it more difficult to put power down, and it probably makes my legs a little more sore. And of course it exacerbates the pedal strike situation somewhat. I still ride it and enjoy it, but it won’t probably see anywhere near the mileage my 36er gets.
If the P@Uni can manage to be narrower than a Huni then you’re probably still in an okay Q-factor range”
From the photos / videos of the Huni-Rex it seems that it is some 5 inches wider than a conventional unicycle (say the 20” Terra_bike: 0.41m or 16”). You know better.
Without some special effort the P@Uni is substantially narrower
And besides being narrower, the P@Uni is also more lightweight, more efficient (follow the number of energy “passages” from the pedals to the wheel), more reliable (the sprocket and the chains are unreliable) and cheaper.
With a 32” or 36” or 40” wheel, geared or not, the P@Uni can be considered as an improved Huni-Rex, at least.
Can’t it?
Thanks
Manolis Pattakos
The Huni-rex is heavy, but it would be perfectly possible to make a lighter weight version, especially at a 1:1 gearing. I struggle to see how your designs are inherently any lighter in design. Can you elaborate?
You can see a DIY version of the same approach part way down here, which has been built in a far more lightweight manner: Riding Faster on One Wheel: Geared Unicycles | Random ASCII – tech blog of Bruce Dawson
I think it would also be prudent for you to mention which design you’re talking about in each case as the two designs you have presented here have quite different positives and IMO feasibility. I only believe that the P@Uni_rp would be ridable.
On a related note, I’ve always wanted to try a pair of swing cranks on a unicycle just for a laugh (Pulse Swing Cranks from Highpath Engineering)
You write:
"Define a single primary user problem you want to address
Separate rider experience arguments from mechanical arguments
Support your claims with data or experience"
It sounds like a patenting handbook.
Things do not work this way.
An idea is an idea. If it is functional then it is evaluated in order to either be rejected or be further developed.
You ask me:
"What rider problem you are solving
How your technical design solves that problem"
Let me reply by asking you:
What rider problem the Huni-Rex unicycle solves? What makes you think that the P@Uni is not solving the same problem?
Also, what rider problem a 36er (geared or not) solves? A 36r P@Uni is solving the same problem, lowering at the same time the saddle and the pedals. Many riders will love the effortless mounting / dismounting and the confidence of being nearer the ground. Some others may want to sit high in order to have time to think during a fall the best way to land.
Thanks
Manolis Pattakos
You write:
“The Huni-rex is heavy, but it would be perfectly possible to make a lighter weight version, especially at a 1:1 gearing. I struggle to see how your designs are inherently any lighter in design. Can you elaborate?”
No it’s not. And a 1:1 ratio doesn’t improve things.
The slicing of the crankshaft and the support of each crankshaft half independently at either side of the fork adds a lot of weight, bending loads and heavily loaded bearings. As the energy travels from sprockets to chains to other sprockets and so on, some is lost. And the mechanism is prone to soon built catastrophic lash / play.
The P@Uni has a direct transmission. Direct? Yes direct. Instead of having the pedal rotatably mounted to the crank, the pedal is located substantially lower on an arm which remains vertical. The heavy downwards force applied to the pedal passes directy to the crank (as directly as from a conventional pedal to a conventional crank). This transmission is more efficient than the transmission of the Huni_Rex regardless of ratio.
You also write:
“I think it would also be prudent for you to mention which design you’re talking about in each case as the two designs you have presented here have quite different positives and IMO feasibility. I only believe that the P@Uni_rp would be ridable.”
The two designs are the same. In one case the rods keep constant the orientation of the arms relative to the frame, in the second case the gearwheels do the same. And with the heavy loads passing directly from the pedals to the cranks, the loads that left for the “synch” mechanism are far from heavy.
As for the backlash which may ruin the Huni_Rex kinematic mechanism, any backlash in the gear version of the P@Uni will cause an insignificant / unnoticeable play of the arms from vertical direction.
Thanks
Manolis Pattakos
You’re making a lot of claims not backed up by evidence, and pretending that the many years of experience of riding (and building) unicycles that people in this thread have means almost nothing.
Gearing on a unicycle, on a budget. Your designs are 1:1, so not the same problem.
Going faster.
Yes, it is. The Huni-rex is heavy. Going 1:1 would permit two smaller sprockets slightly closer together, reducing weight.
I still don’t see how your design is inherently any lighter.
If you’re trying to improve efficiency then I think you’re aiming in the wrong place. A standard unicycle will always be more efficient, but the efficiency losses are going to be of little importance to the vast majority of riders.
We’re just going to have to agree to disagree on this point. By my eyes they’re clearly not. The theory is similar but the designs are not at all the same.
I doubt this very much. I think the play which is independent on each side will be very noticeable. Maybe you underestimate how little play is obvious and annoying when riding a unicycle. The play in the other version I suspect will be fine if the construction and bearings are of high quality, and a little annoying but probably OK if they’re not.
I don’t think many riders are ever going to ride this, but I wish you luck and look forward to seeing your prototypes.
No, as the Huni-Rex the P@Uni can be geared, too, it also can have its pedals at the same lower height, so for the rider it makes no difference excluding the width.
As the typical 36er, going faster is (between others) a user problem a 36er P@Uni solves too, allowing the rider to go as fast as with any other 36er.
A Huni-Rex 1:1 is still heavier and wider and not so efficient; and while it is “geared”, it is not really geared (1:1 ratio); and for the rider its true difference from the conventional unicycles is the lower pedals. The lower pedals charasterises the P@Uni too.
For the rider, a not-geared 26er P@Uni (direct transmission) with its pedals at the same height with the pedals of a Huni-Rex 1:1, is the same (excluding the smaller weight of the P@Uni, its smaller width, its better efficiency, its longer time between overhalls…)
Thanks
Manolis Pattakos
Thanks for posting your designs, it is nice to see some innovative ideas, it is how things progress.
From my own perspective I like to toy around with ideas for various ‘improvements’ to unicycle design – like suspension which decouples the pedals from the suspended wheel. Mostly it is just ‘thought experiments’ and musings, like the Schmidt coupling based suspension idea I have previously mentioned on here, or a mechanism to counteract pedalling torque (around the vertical axis) instead of relying on a handlebar. With most of these the actual benefit it brings is dubious and marginal at best, but the intellectual challenge makes it attractive to me. (A ‘full-sus’ unicycle is not going to be holding its own against a bike on a World Cup DH race… 
) In many ways the pointlessness of it is also worthwhile for me as an escape from real-world engineering challenges I actually get paid to solve! Overall though, the level of complexity obviates any tangible benefit, but that said, in the grand scheme of things a unicycle is not the most practical method of transport, so that maybe doesn’t matter (hopefully this statement doesn’t get me kicked off of here 
).
If I ever have time to flesh these ideas out and get them to actually work they will result in, at best, a curiosity in a ‘mad inventor’ sort of a way, certainly not something that is commercially viable, at least at any degree of scale; bespoke custom builds for likeminded people perhaps, but not in the “mainstream” (!) unicycle world
I’m maybe wrong, but I don’t think there would be any significant commercial future for your designs, the market is simply too small and the level of engineering required too high to give a reasonable price point. I don’t think that should stop you from pursuing them though, in my mind at least it is not really about shipping units.
I wish you luck and look forward to seeing a real world prototype. Your models are nice and certainly further than I have ever got, and it would be good to see the real thing and get someone to actually try it and perhaps demonstrate the value.
I’m just waiting for someone to take a hint from SRAM/Shimano’s wireless shifter and make a Schlumpf shift wirelessly 
. I’ve never looked at (or been qualified to look at) the internals of the Schlumpf hub, but that might be a way to put more gear ratios in there?
