3D Modelling a Muni

Hi everyone,

I want to model a MUni for a friend and the best part to start it seems to be the hub. Unfortunately I dont have a Unicycle and it does not seem like there is any kind of datasheets online for a QuAx or similar.

Can some please just take a ruler/ calliper and give me some diameters? I know for instance that the bearing is 12mm wide and has an external diameter of 42mm, as well as the length between the middle of the two bearings is 100mm. But I cant find anything about the diameter or width of the part where the crank is positioned, or the hights of the part where the spokes sit, or the distances between these parts…

more or less just this picture but with numbers…

Thanks a lot,

You might find the UDC spoke length calculator interesting.

Doesn’t have every dimension, but quite possibly enough to figure out some of the others by scaling pictures to the given dimensions. And you can select various model components from the dropdowns and get the indicated dimensions filled in.

Be aware almost each hub has unique sizes, but yes, in general bearing pitch and sizing is more standard.

That’s the most common bearing size for ISIS. But what you show is JIS.

yes, im aware of the many many differences…it drives me crazy while searching. The picture is just a reference.

ahahhh!!! thats something i can start with.
As well i think im going for an ISIS…

(sry for doublepost)

More than you could ever want to know regarding ISIS spline spec.


Potential product

Good luck with the solid modeling. I will try to give you some measurements also, but I’m lazy and taking it out of my trunk, finding the right tools, extracting bearings, finding my caliper and measuring means only one thing to me…i won’t be riding. However, I will get it together soon.

I’m also a M.E. and a uni-rider. (key to being a good engineer…also be the “user/customer”…never be a slave to someone else’s specs.) Here’s a thought for a possible “thing” to design. Try to figure out a way to disengage the wheel shaft from the cranks/pedals. Why? So you can coast down a hill, and still keep your feet on pedals for balance? Not talking about “gliding”. You know…taking your feet off pedal…and pure seat balancing. That’s for circus experts. Just talking about somehow “clutching” between the wheel shaft and cranks. Of course, it should be “normally locked” and then manually(or electronically…yes, electronics: just a battery/solenoid/switch…no CPU/bluetooth/app sh*t). Just look at existing machine components(car clutch, drum brakes,…etc.). A car clutch relies on very compact disk type spring(belleville, washer, disk…) and then disengaged with a lever. A drum brake relies on very thin but large area surface high friction shoes with very small radial displacement. With lipo’s so small and high voltage these days maybe consider a solenoid. Whatever…you’ll figure it out if you care and if you ride.

As a rider, I don’t really care about a $1000 schlump planetary gear tranny to go faster. However, just being able to free wheel with my feet “still on pedals” for stability is appealing. Give that some thought. I’d pay a a hundred bucks or two for that. Final hint. I’m thinking this will require concentric hollow and solid shaft, and forget about a splined hub. The clutching friction will “act as” the spline/lock. Good luck. Final Final hint(actually a design requirement) if you like to idle then you will want shaft locked in both direction…so forget about using a one way needle bearing. Good luck young inventor!!

Nice ideas, but isn’t he doing just a 3d model?

Well, first the part on the actual topic on this thread: Moocow unicycles offers all their technical drawings for free, maybe you can get some of your measurements there: http://moocowunicycles.com/OpenSource.html

Now to the off topic idea of disengaging the pedals via a clutch: while it certainly is possible and may seem desireable on the first sight, let me tell you something about coasting: It’s not just hard, it’s also not relaxing at all, and even less so when you coast downhill.

Unicycle.com already sells a freewheel hub here if that’s what you’re looking for. I use it for MUni and it works really well. http://www.unicycle.com/nimbus-drift-trike-disc-cotterless-hub-36-hole/

I don’t think coasting with feet on pedals is any easier than coasting with feet on frame. Try a freewheel hub as AJKJ suggested. It is extremely hard and with a freewheel hub you can at least still balance in one direction.