Hey all,
I have been thinking lately, why do trials unicycles only use 36 hole, while most good trials rims are 32 hole? Also, why do flanges have to be so fricking weak? I know a couple of very good machinists and was thinking of making some very strong (yet still light) 32 hole unicycle hubs. I’m going to base my hub design on Chris King hubs (hourglass design), so the flanges will be strong while still remaining light. Any comments or suggestions?
PS, they will be ISIS splined with a hollowed (light yet still strong) axle.
If you have a model, please post pics 
Very intresting topic I say.
Peter M
http://www.unicyclist.com/index.php?page=gallery&g2_itemId=277572
http://www.unicyclist.com/index.php?page=gallery&g2_itemId=277575
Heres my custom hub.
Unfortunatly it got a defect again, so i will send it back to my mate to fix it.
The axle is from an old old onza hub (2003) and the rest is made by a friend of mine.
this is just in the planning and design phase, also, these will run pricy because of the fact that they will be hand turned on a lathe.
very nice, good machine work. This hub design is similiar, cept a little more dished. How big should the flanges be? (metric please.) Also, how is the demand for a disc hub?
i can measure it tommorow maybe, im pretty short on time right now. My friend did all the work (design and building).
Aren’t most trials rims designed for trials b*ikes and not unicycles?
Broken a flange? I haven’t seen many (if any) pictures of broken flanges here.
I’d suspect a nipple or spoke would break before a flange on a large impact, unless you’re using your unicycle for something other than trials riding.
That being said, good luck with your design… be sure to post plans and pictures!
Good luck with that. I hope you’ve done a bunch of machine work already, because things like ISIS splines aren’t easy to make, let alone the tediousness of milling hub parts. If you’re using a manual lathe for the basic hub form, doing anything but simple straight tapers and diameters will be very difficult.
I’m curious, are you planning to use cnc tools or manual? If you do manual, economies of scale are going to be almost nil, and pretty much every hub will be just as hard to make as the last. If you do cnc, it will be initially more expensive and harder to do, but ultimately a more uniform, cheaper product.
I just got a job at a large cnc machine shop that specializes in high-end aerospace parts (things ranging from simple door mounts for 747s to chinook helicopter rotor hubs to langing gear parts for F-18s and F-22s). Hopefully I’ll get the time on one of the smaller machines to make some high-end unicycle parts, but really I just want to play around with concepts, and nothing will be made for other users.
I strongly recommend against taking orders before you have at least one hub in a wheel and ready to ride. You’d be amazed how much stuff comes up when toying with designs.
The ISIS axles are already available (Bike axels), I’ll just be manufacturing the hubs, I have been machining for 3 years and still don’t think I have the prowess to attempt an ISIS axle by hand. This will be done with both cnc and manual, as I prefer to do things by hand (aka manual) So if I f**k anything up it’ll only happen once, not every time I go to do it. In case you’re curious, the hub will be 7075 aluminum while the axels will be hardened 4130 cro moly steel.
Edit: I am not taking orders by the way, just guaging interest. (Testing the waters, so to speak) Also, The flange thing is because of failed side hops and pedal/crank grabs, maestro, because the typical unicycle flange is really quite weak. (KH, Koxx, Nimbus, etc.)
A-ha. Sounds good. Manual is more fun, but lately I’ve been getting into some more cnc, and it does open some doors. Ever tried doing something like an impeller vane or compressor blade for a turbine in manual machining? Someone showed me how they used to do it, and man, cnc sure does look good.
Are ISIS BB axles wide enough for unicycles?
Check out a profile hub. They have much stronger flanges (laterally) than the classic KH, etc.
I warn you, doing the interference fits and keyways for a unicycle hub is pretty difficult. Profile had quite a bit of trouble with its design, as well as a number of machinists who tried to fix things after the fact (pins, etc).
Once again, good luck. I’ll be interested to see the results.
Yes, the current hub manafactureres use off the shelf bike axles in their hubs. KH mentioned once that the reason he couldn’t make a wider splined hub for cokers was that he couldn’t get a stock axle that long, and having one made was unviably expensive.
Unicycles put a lot more stress on parts than trials bikes, hence more spokes.
Why custom, asside from an interesting project?
I’m doing this just for sh*ts and giggles really, just for fun.
That is the best reason to do it… (and if it’s a pain you’ll never want to do it again even if someone pays you :D) What is the intended usage of your hub?
Trials, it’ll cost me like >50 bucks to make, so why the hell not?
Now this is a brilliant idea, do you have any sketches done yet? Let us know more about your project, I’ve been hoping to see 32hole hubs for some time now!
I have some sketches, but I don’t trust computers, all my blueprints are on paper. I’ve wondered why we hadn’t gone 32hole for some time now, and it isn’t because we put too much stress on trials rims! They use 1 wheel too! I’ll be puting a Meta or Echo rim on it, depending on which I get first.
I think it’s just because we use the old system, bike trials used to be 36h as well. How much does an ISIS axle cost? So the complete package, I might know someone who would be interested in making a hub too 
I didn’t say you shouldn’t
If you are planning to do this much work I can’t help but wonder why you wouldn’t also go and find Rim-blanks and make a wheel-set with a ridiculously large number of spokes instead of making one with less spokes than the typical trials wheel set. It sounds like your intent is to build a beefy hub that you can beat the snot out of.
Huh? Backups are your friend if you are worried about loosing data. And if you build the entire thing in software it is very easy to check for physical conflicts. And I though you were sane, unlike the rest of the people here.
@Dustin: Why are bike trials wheel-sets no longer 36 spoke if that’s what they used to be?