Wheel hubs for pneumatic tires (aka Janux hubs) for sales

Janux hubs are machined from solid rounds of Acetal Delrin, not 3d printed. Hubs were designed to fit the following 6x2” pneumatic tires: https://www.aliexpress.com/item/6X2-tyre-6-Inch-Scooter-Tire-Inner-Tube-Set-Electric-Scooter-Wheel-Chair-Truck-Electric/32840513077.html?spm=a2g0s.9042311.0.0.czdUJy. I can also modify them to your specs.

Hubs come in 2 halves, bolt together with 3 x M6 hex caps. Hub diameter is ~74mm, rim diameter ~90.5mm, rim (lip or bead) is 5mm thick, overall thickness ~43mm. Wheel spacers are replaced with bearings for smooth running and to provide extra support for the entire thickness of hub. Each hub is supported by 4 bearings - two bearings are on the outside facings and two on the hub interior, replacing wheel spacer. Hub is practically riding along the entire length of 4 bearings.
Please specify the truck when ordering, ie MBS, Trampa MTB Spring, Trampa Carve,…

  • Set of 4 hubs - $150 (specify truck)
  • Set of 16 bearings - $16
  • Customizable POM pulleys - $ according to spec (44 - 72t)
  • US shipping $8, International shipping $25

What is Acetal? Acetal resins, aka POM (polyoxymethylene) or acetal Delrin are engineering thermoplastics based on formaldehyde polymerization technology. These highly crystalline resins are strong, rigid and have a low coefficient of friction against metals, acetals and other plastics. They are creep resistant so they are good for parts where dimensional stability is important.

POM have high tensile strength, stiffness, resilience, fatigue endurance and toughness. They have high resistance to organic solvents, excellent dimensional stability, a low coefficient of friction and outstanding abrasion resistance among thermoplastics. Acetals’ resistance to creep is excellent. Moisture, lubricants and solvents including gasoline and gasohol have little effect on this property, which is important in parts incorporating self-threading screws or interference fits.

Solid round of 4" x 12" Acetal Delrin IMG_2785

Stock sliced into 1" thick pucks, machined flat and true on both faces, and individual cnc’ed IMG_2826

Inner and outer halves


Wheel spacer replaced with dual inner bearings IMG_2831

Quad bearings run entire length of hub



Customizable pulleys 44-72t IMG_2841

Available in black and white IMG_2842

Outer face with 6 x 10-24 hex bolt pulleys

Inner face, note: the 4 bearings along the hub axle

Easy installation of hub to tire

Insert inner half to opening IMG_2850

Mate outer half with 3 M6 bolts IMG_2853



they are looking great!

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Looks beautiful. If you now design an inner gear direct drive system you basically offer everything I ever wanted out of POM.

Three things you might want to consider:

  1. I think we had my 3D printed hubs improved by a guy by adding an additional edge on the inside of the outer rings. This helps center the tire properly.

  2. I don’t get the 2 bearings as spacers thing. How does that work? The outside bearings need to be seated so there is definitely some distance until the next (inner) bearing - this then already defeats the purpose of spacers when the bearing is allowed to “bend” inwards while torquing down the axle but.

  3. you might want to adjust the bearing to bearing distance to allow the usage of standard skate spacers. This would then make these general purpose hubs that can be mounted on standard trucks.


1- 3d printed parts do not give you the precision of an industrial CNC machines.

2- I opted for the inner bearings instead of the wheel spacer because they felt so much more solid. Each bearing had its own housing and precisely machined to fit with minimal play. When torqueing down the axle nut there is no “bend” inwards because inner bearings sit flush with respect to each face and the halves are face-mill trued and perfectly matched to each other. with that said, it does not mean you could not use the wheel spacer instead.

3- Based on the truck you have the bearing housings are modified accordingly.

Oh…an inner gear direct drive system is a possibility in the future.

  1. Even metal hubs have the inner edge to help make the tire sit correctly. That’s where he got the idea from. This has nothing to do with 3D printed parts

  2. no bend is impossible. It just can’t be as there has to be a small lip the bearing sits against. The thickness of that lip has to be overcome by bending. No way around that. Only thing would be bearings that extend further on the inner ring than the outer or by adding washers.

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1- If the tire opening measured 75mm then my hub is made to 75mm diameter. Maybe the inner edge make the tire sit correctly, but is it critical? Probably not a whole lot.

2- Maybe “bending” is not the right term to use with my hub. Hub does not bend because it’s almost 1 3/4" thick solid core Acetal, impossible to bend. Together with bolted hub and the 5mm thick outer rim squeezed the tire and even more so when tire is inflated.

  1. the edge is to make the tire sit centered and to minimize wobbles. When inflating, the tire will change its shape and move outwards - basically making its inner “hole” diameter wider.

  2. I am not talking about the hub bending - but the bearing itself has to deform. That’s what spacers are for - to keep the bearing from deforming while being able to torque down the axle but properly. See: https://stokedrideshop.com/blogs/bearings/why-bearing-spacers-really-matter

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The 2 inner bearings served as the wheel spacer. Bearing housings are precisely machined to sit without lateral play. When torqueing down the axle the bearing would not deformed because there are no gaps between the inner bearings and the housing.

Like I mentioned above, traditional wheel spacer can be had with my hub if my concept seem foreign. I just experiment with the quad bearings and they feel very solid and smooth running. So I decided to offer to people on this forum.

Pablo Picasso once said “I am always doing things I can’t do, that’s how I get to do them.”

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You don’t seem to understand what I mean. There is literally no way your technique can work without adding washers. The bearing seat has to have a certain thickness so the races of the bearings are apart by that distance. By torquing the axle nut you will bend the bearings until the inner races touch - since the outer races are fixed the bearings are now deformed. I’ll post a drawing tomorrow.

Edit: maybe deformed is the wrong word - misaligned might fit better.

Looks cool @marcmt88 :sunglasses:

Is it just me or do those tires look like the ones psycho sells with his sixshooters? :thinking:

They are the same. Me and @psychotiller have been using them for quite a while. They are readily available on AliExpress.

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I included a link for those tire in the description above :point_up:

I understand your concern completely. It’s just hard to explain the quad bearing concept. It’s comforting to see the things that are familiar to us. Why not think outside of the box and experiment something different and new. Just wish you can see how this work in person. Again, these hubs are cnc machined to a tolerance of 0.01mm, human hair is 0.05mm.

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Maybe this concept drawing make it easy to understand. Gaps between the bearings and housings are exaggerated to make a point. Inner bearing housings are 8mm deep which correspond to 8mm thick bearings (MBS and Trampa Spring). They sit flush to each half of hub. Torqueing down the outer bearing does not caused deformity because there are no gaps to give way between the two inner bearings.

Sorry, the bottom arrows are pointing the outer bearings.

I think the worry was more to do with the inner races?

Are you making different versions for 10mm bearings(10x22x6)?

Next release…All terrain/mountain board motor mount



There are 3 different bearings sizes: 8mm to fit standard bearings, 9.525mm to fit Trampa Carver, or 12mm to fit MBS and Trampa Spring trucks.

But there are gaps between the outer and inner bearings. Torquing the nut will cause the outer bearing to deform so that it’s inner race touches the inner race of the inside bearing.

Edit: You could add washers so that there is no gap between the inner races - then everything’s fine. But finding a suitable washer depends on the gap size you chose in your hub.


yea. @maxid is right. try tightening 2 bearings against each other.

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